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A model combining landings and VMS data to estimate landings by fishing ground and harbor
Abstract
At present, the assessment and management of Adriatic Sea fishery resources are based on data that do not fully account for the complex spatial patterns arising from fleet behavior and/or species' behavior and biology, mainly because logbooks do not guarantee adequate coverage of the fishing activity exerted by the fleet. For data collection, the Adriatic Sea is divided into two management areas (namely FAO Geographical Sub-Areas-GSAs). To account for these spatial patterns while using the data available, we propose a method for estimating the monthly landings of Italian trawlers operating in the Adriatic Sea at a higher spatial resolution than the GSA. We use a stepwise approach based on the combined analysis of questionnaire-derived vessel-specific landings and the spatial activity of the vessels with respect to a set of fishing grounds. Thus, we sequentially 1) analyze the available vessel monitoring system data, 2) partition the study area into fishing grounds (the origin of the landings), 3) cross analyze vessel-specific fishing efforts with the available vessel-specific monthly landings to estimate the LPUE of each fishing ground, and 4) estimate the monthly landings (by vessel, fishing ground, and harbor) for the whole fleet and the monthly fluxes between fishing grounds (origin) and landing harbors (the destination of the landings). We apply the method to two species: the Norway lobster and the European hake. For both species, we find a few fishing grounds to be consistently more productive than others and the landings per harbor to vary greatly but with few harbors regularly receiving a significant share. In particular, the results suggest that the Pomo/Jabuka pit area represents a critical area for both species. Additional outcomes include a detailed characterization of the activity of the Adriatic bottom trawling fleet, highlighting the strengths and shortcomings of the official data available. We discuss the results in the context of the current management paradigm.
... The assessment of fishing traits of each CCA and the Northern Ionian Sea was carried out through the SMART modelling approach, a method able to reconstruct the spatial and temporal fluxes of landings coming from well-defined areas (fishing grounds) and times to harbors to which they are delivered for sale (Russo et al., 2018;Russo et al., 2014;D'Andrea et al., 2020). The modelling of spatial fishing effort is based on the use of information obtained by the Vessel Monitoring System (VMS), which is applied to the remote control of fishing vessels with length overall (LOA) ≥ 15 m in European waters (EC, 2011). ...
... Starting from this information on the spatial effort and landings, it is possible to estimate the Landing Per Unit of Effort (LPUE, kg h -1 km -2 ) for each vessel length (D'Andrea et al., 2020). In addition, a reconstruction of the effort and production data for vessels with a LOA < 15 m was carried out using the European Common Fleet Register (EC, 2010) according to the method reported in Russo et al. (2018). ...
... 1. Analysing VMS data to assess the fishing effort by vessel/ cell/time; 2. Processing landings data, combined with VMS data, to estimate the spatial/temporal productivity of each cell (or spatial unit), in terms of mean monthly LPUE by species, according to the method described and applied in Russo et al. (2018); ...
The assessment of the spatial overlap between eligible cetacean conservation areas (CCAs) and fishing grounds could be a strategic element in the implementation of effective conservation measures in the pelagic offshore areas. A multi-species bio-economic modelling approach has been applied to estimate the fishing traits in eligible CCAs in the Northern Ionian Sea (NIS, Central Mediterranean Sea) between 10-800 m of depth, adopting the Spatial MAnagement of demersal Resources for Trawl fisheries model (SMART). Four possible CCAs were defined according to the distribution of cetacean species, their bio-ecological needs, as well as socio-economic needs of human activities, identifying a Blue, Red, Orange and Green CCAs in the NIS. SMART spatial domain was a grid with 500 square cells (15×15 NM). The analysis was conducted for the period 2016-2019, considering the Otter Trawl Bottom (OTB) fleet activities in the study areas through the Vessel Monitoring System. The spatial extension of fishing activities, hourly fishing effort (h), landings (tons) and economic value (euros) for each CCA and the NIS were estimated as yearly median values. Fishing activities were absent in the Blue CCA, where the presence of the submarine canyon head does not offer accessible fishing grounds. The hourly fishing effort in the Green area accounted for about 22% (3443 h) of the total hourly effort of the NIS, while the Orange and Red areas were about 8% (1226 h) and 2% (295 h), respectively. The Green CCA corresponded to about 14% (36 tons) of the total landings in the NIS, whereas the Orange and Red areas represented about 9% (22 tons) and 6% (16 tons), respectively. The Green CCA accounted for about 13% (156 thousand euros) of the total economic value of the NIS, while the Orange and Red areas represented about 6% (69 thousand euros) and 4% (44thousand euros), respectively. Results showed no or negligible negative effects on trawl activities by potential spatial restrictions due to the establishment of CCAs highlighting the importance to consider spatially integrated information during the establishment process of conservation areas for cetacean biodiversity according to the principles of Ecosystem Based Management.
... In particular, the central part of the Adriatic Sea, characterised by 3 depressions delimited by the 200 metres bathymetry (having a maximum depth of about 270 metres [56]), together known as Pomo (or Jabuka in Croatian) Pits, is one of the main fishing grounds within this basin, shared by the Italian and the Croatian fleets [57,58]. According to Russo et al. [58], the main fishing zone for the Italian fleet targeting Norway Lobster and European Hake is the one located just south of the Pomo/Jabuka Pits (Figure 1). ...
... In particular, the central part of the Adriatic Sea, characterised by 3 depressions delimited by the 200 metres bathymetry (having a maximum depth of about 270 metres [56]), together known as Pomo (or Jabuka in Croatian) Pits, is one of the main fishing grounds within this basin, shared by the Italian and the Croatian fleets [57,58]. According to Russo et al. [58], the main fishing zone for the Italian fleet targeting Norway Lobster and European Hake is the one located just south of the Pomo/Jabuka Pits (Figure 1). The complex topography of the area, combined with the oceanographic regimes of the Adriatic Sea, makes it a very peculiar environment in which the water exchange does not occur every year [59]. ...
... In the up-right rectangle the position of the study area within the Mediterranean basin is highlighted (red circle). The main map shows: central Adriatic Sea bathymetry (source: [56]) and stratification in use within this study (dotted areas; zone "A", "B", and "ext ITA"); position (triangles) of the trawl hauls considered within this study; main fishing area (black grid) for the Italian fleet targeting Norway Lobster and European Hake, according to Russo et al. [58]. ...
A Before–Intermediate–After Multiple Sites (BIAMS) analysis, namely a modified version
of the Before–After–Control–Impact (BACI) approach, was used to evaluate the possible effects of fishery management measures implemented in the Pomo/Jabuka Pits area, a historically highly exploited ground for Italian and Croatian fisheries, whose impact may have contributed over the years to the modification of the ecosystem. Since 2015, the area was subject to fishing regulations changing the type of restrictions over time and space, until the definitive establishment in 2018 of a Fishery Restricted Area. These changes in the regulatory regime result in complex signals to be interpreted.
The analysis was carried out on abundance indices (i.e., kg/km2 and N/km2) of five commercially or ecologically relevant species, obtained in the period 2012–2019 from two annual trawl surveys. BIAMS was based on the selection of a Closure factor, declined in three levels (i.e., BEFORE/INTERMEDIATE/AFTER) and accounting for regulation changes in time, and on three adjacent strata (i.e. “A”, “B”, and “ext ITA”) a posteriori determined according to the latest regulations. BIAMS allowed us to identify early effects (i.e., changes in abundances), overcoming the unavailability of a proper independent control site; furthermore, the selection of adjacent strata allowed the inference of possible interactions among them.
... Analysis of fleet mobility can provide valuable support for a wide range of studies, such as the drafting of management plans for the sustainable exploitation of fishery resources [1,2], the detection of possible conflicts among different fishing activities [3], the monitoring of effort displacement [4,5], and the identification of mismatches between catch and registration site [6,7]. The introduction of systems providing high-resolution fishing vessel position data, such as the Vessel Monitoring System (VMS) and the Automatic Identification Systems (AIS), has revolutionized the study of the fleet mobility and many patterns have been described worldwide [8,9]. ...
... This dynamism is not properly caught by the geographical sub-division system used to collect fishery statistical data, including catches, which may appear too rigid [7]. In fact, the units adopted for the collection of fishery statistical data and stock assessment in the Mediterranean Sea (Geographical Sub-Areas; GSAs) [14] are a division that actually reflects less the actual geographical distribution of stocks and fleet exploitation patterns than the geopolitical borders, potentially undermining the accuracy of fishery statistics [6,11]. EU and non-EU Mediterranean countries often fail to provide catch statistics for their fleets operating in remote areas, releasing only those based on GSAs (for an example see [15,16]). ...
... A number of factors, such as fishing ground accessibility, time at sea restrictions and differences in vessel technology and size [16], as well as market prices [13], contribute to shape the fishing strategies adopted by Mediterranean fleets. AIS data per se cannot give information on vessels landings, and only logbook data [34] may confirms if the harbor of arrivals was used for bunkering or for unloading the catches [6]. Nevertheless, literature may be used for hypothesize on the factors driving the mobility patterns described. ...
In the Mediterranean Sea, fishing vessels often operate throughout the geographical subdivisions adopted for
statistical data collection (Geographical Sub-Areas; GSAs), causing a potential mismatch between catches site and
reporting site. This paper provides a quantitative assessment of the fluxes of fishing activity of bottom trawlers
across the Mediterranean Sea, by analyzing the Automatic Identification System (AIS) data broadcasted in 2017.
Fishing activity was analyzed from three perspectives: fishing site, port of arrival and registration site of the
vessel. For each GSA, a “fidelity score” was calculated to quantify the proportion of fishing time spent in the
home GSA; an “intrusion score” was computed to quantify the effort deployed by vessels registered elsewhere.
Major vessel fluxes were detected between GSAs, and fleets were classified based on their mobility. Areas
showing fleet overlaps were identified and those characterized by the largest overlaps were selected as case
studies. The lowest fidelity scores were observed in the central Mediterranean (GSAs 11.2, 15, 16 and 18), while
the highest intrusion score was recorded in the southern Mediterranean and around Crete. The vessels responsible
of the largest fluxes were those registered in GSAs 16, 18, and 6. The case studies included: GSAs 23, where
several fleets exploited narrow slope areas; GSA 13, where multiple fleets overlapped in a relatively wide area;
and GSA 17, where two fleets overlapped in a wide platform area. Mobility was distinguished in short-range –
involving platform areas of contiguous GSAs – and long-range – involving slope areas of non-contiguous GSAs.
... A total of 367 of these are equipped with vessel monitoring systems (VMS) and were considered for this study. The LOA of each vessel was retained from the EU Community Fishing Fleet Register 4 and used as the best proxy of vessel's fishing capacity (Russo et al., 2018). The fishing effort deployed by each Italian trawler operating in the SoS was quantified, for the 60 months in the years 2012-2016, using VMS data provided by the Italian Ministry of Agricultural, Food and Forestry Policies, within the scientific activities related to the Italian national program implementing the European Union Data Collection Framework in the Fishery Sector. ...
... The amount of fishing effort (in fishing hours) was estimated for each trawler/month/cell of the grid ( Figure 1D). Although logbook data could represent the main source of information about catch and landing (Gerritsen and Lordan, 2011), several reasons (see Russo et al., 2018 for a detailed list) supported the adoption, in Italy and other similar Mediterranean countries, of a statistical sampling scheme, based on questionnaires filled by researchers at harbors, to collect vessel-specific monthly landing data (EC, 2008;EUROSTAT, 2015). These data for the Italian trawlers operating within the SoS in the period of interest were therefore used in this study. ...
... This grid is coherent with the one defined by the GFCM 5 Although several studies demonstrated that large spatial scale could lead to distortions in the analysis of fishing effort and related spatial indicators (Mills et al., 2007;Lambert et al., 2012;Hinz et al., 2013), the spatial resolution applied in this study was selected to harmonize coverage (i.e., number of observation by cell) over different data sources (i.e., VMS, landings and CAMPBIOL) and to limit the number of spatial units (cells), which is a critical parameter affecting computational features of the model. The rationale of the model, as well as the workflow 1. Processing landings data, combined with VMS data, to estimate the spatial/temporal productivity of each cell, in terms of aggregated landings per unit of effort (LPUE) by species, according to the method described and applied in Russo et al. (2018); 2. Processing biological data to estimate LPUE by age and by species, for each cell/time; 3. Analyzing VMS data to assess the fishing effort by vessel/cell/time; 4. Combining LPUE by age with VMS data to model the landings by vessel/species/length class/time/cell; 5. Estimating the cost by vessel/time associated with a given effort pattern and the related revenues, as a function of the landings by vessel/species/length class/time (step 4); 6. Combining costs and revenues by vessel, at the yearly scale, to obtain the profit, which is the proxy of the vessel performance. profit could be aggregated at the fleet level to estimate the overall performance; 7. Using estimated landings by species/age, together with survey data, to run mice model for the selected case of study in order to obtain a biological evaluation of the fisheries. ...
In the last decades, the Mediterranean Sea experienced an increasing trend of fish stocks in overfishing status. Therefore, management actions to achieve a more sustainable exploitation of fishery resources are required and compelling. In this study, a spatially explicit multi-species bio-economic modeling approach, namely, SMART, was applied to the case study of central Mediterranean Sea to assess the potential effects of different trawl fisheries management scenarios on the demersal resources. The approach combines multiple modeling components, integrating the best available sets of spatial data about catches and stocks, fishing footprint from vessel monitoring systems (VMS) and economic parameters in order to describe the relationships between fishing effort pattern and impacts on resources and socio-economic consequences. Moreover, SMART takes into account the bi-directional connectivity between spawning and nurseries areas of target species, embedding the outcomes of a larvae transport Lagrangian model and of an empirical model of fish migration. Finally, population dynamics and trophic relationships are considered using a MICE (Models of Intermediate Complexity) approach. SMART simulates the fishing effort reallocation resulting from the introduction of different management scenarios. Specifically, SMART was applied to evaluate the potential benefits of different management approaches of the trawl fisheries targeting demersal stocks (deepwater rose shrimp Parapenaeus longirostris, the giant red shrimp Aristaeomorpha foliacea, the European hake Merluccius merluccius, and the red mullet Mullus barbatus) in the Strait of Sicily. The simulated management scenarios included a reduction of both fishing capacity and effort, two different sets of temporal fishing closures, and two sets of spatial fishing closures, defined involving fishers. Results showed that both temporal and spatial closures are expected to determine a significant improvement in the exploitation pattern for all the species, ultimately leading to the substantial recovery of spawning stock biomass for the stocks. Overall, one of the management scenarios suggested by fishers scored better and confirms the usefulness of participatory approaches, suggesting the need for more public consultation when dealing with resource management at sea.
... In the Adriatic Sea, Nephrops is subjected to high fishing pressure from fleets of different countries [56]. Relevant concentrations of this species occur off Ancona, in the Pomo/Jabuka Pits and in the Velebit Channel [53,[57][58][59][60][61][62]. ...
... spring 2015) for which the spatial distribution of the indices within the maps were mostly centered in the south-east zone of Pomo/Jabuka Pits. A pretty similar distribution of Landings Per Unit of Effort (LPUEs) was previously estimated by a model developed by Russo et al. [56] which estimates Nephrops landings per fishing ground combining landings per harbor and fishing vessels routes from VMS (Vessel Monitoring Systems [119]). Besides, a displacement model by Bastardie et al. showed a possible redistribution of the fishing effort toward surrounding areas in case of establishment of a fishing ban within the Pomo Pits [28]. ...
Abundance and distribution of commercial marine resources are influenced by environmental variables, which together with fishery patterns may also influence their catchability. However, Catch Per Unit Effort (CPUE) can be standardized in order to remove most of the variability not directly attributable to fish abundance. In the present study, Generalized Additive Models (GAMs) were used to investigate the effect of some environmental and fishery covariates on the spatial distribution and abundance of the Norway lobster Nephrops norvegicus within the Pomo/Jabuka Pits (Central Adriatic Sea) and to include those that resulted significant in a standardization process. N . norvegicus is a commercially important demersal crustacean, altering its catchability over the 24-h cycle and seasons according to its burrowing behavior. A historically exploited fishing ground for this species, since 2015 subject to specific fisheries management measures, is represented by the meso-Adriatic depressions, which are also characterized by particular oceanographic conditions. Both the species behaviour and the features of this study area influence the dynamics of the population offering a challenging case study for a standardization modelling approach. Environmental and catch data were obtained during scientific trawl surveys properly designed to catch N . norvegicus , thus improving the quality of the model input data. Standardization of CPUE from 2 surveys from 2012 to 2019 was conducted building two GAMs for both biomass and density indices. Bathymetry, fishing pressure, dissolved oxygen and salinity proved to be significant drivers influencing catch distribution. After cross validations, the tuned models were then used to predict new indices for the study area and the two survey series by means of informed spatial grids, composed by constant surface cells, to each of which are associated average values of environmental parameters and specific levels of fishing pressure, depending on the management measures in place. The predictions can be used to better describe the structure and the spatio-temporal distribution of the population providing valuable information to evaluate the status of such an important marine resource.
... The Adriatic Sea is a semi-enclosed basin within the Mediterranean ( Fig. 1; Artegiani et al., 1997;Poulain et al., 2001). It represents one of the most intensively fished areas in Europe (Eigaard et al., 2017), where N. norvegicus is one of the most targeted species (Russo et al., 2018). The Northern-Central part of the Adriatic, namely the GSA 17 (Geographical Sub-Area 17 according to the subdivision of the General Fisheries Commission for the Mediterranean; GFCM, 2009), is characterized by an extended continental shelf, eutrophic shallow waters (Campanelli et al., 2011), and a seabed mainly composed of sediments of varying composition and grain size (Frignani et al., 2005;Droghini et al., 2019). ...
... In spring 2019, CNR IRBIM Ancona staff carried out sampling of N. norvegicus in two of the main fishing grounds for this species within GSA 17: the off Ancona fishing ground and the Pomo Pits area ( Fig. 1; Russo et al., 2018;Angelini et al., 2020). These sampling activities were carried out in the framework of two different programs funded by the Italian Ministry of Agricultural, Food and Forestry Policies (MIPAAF): a biological sampling of commercial catches carried out within the European Data Collection Framework (EU, 2008) and the monitoring of the Pomo FRA . ...
This study reports the shapes, dimensional classes, types and counts of microplastics (MPs) found in 23 individuals of N. norvegicus collected from two wild populations of the Adriatic Sea, (Mediterranean basin). The focus was on three different anatomical compartments (gut, hepatopancreas and tail), which were analysed separately. MPs were found in all the investigated individuals with an average of about 17 MPs/individual. Fragments were predominant over fibers with a ratio of about 3:1. The majority of MPs were in the dimensional range 50-100 μm. The predominant polymers were polyester, polyamide 6, polyvinyl chloride and polyethylene, which together constitute about 61% of all the MPs found. Fragments were more concentrated in the hepatopancreas, with no significant difference between gut and tail, while fibers were more concentrated in the gut than in the tail with hepatopancreas somehow in between. The dimensional class of the MPs influences their anatomical distribution. There were no statistical differences among individuals from the two sampling sites. Sex of the individual did not influence the level of retained MPs, while length had a very marginal effect. The information reported here contributes to understanding of the possible risks linked to human consumption of different tissues from contaminated Norway lobsters.
... In marine systems, onboard observers and logbooks have been complemented recently by vessel monitoring systems (VMS), which use satellite-based transmissions to track commercial fishing at the national level. Analyses of VMS data have identified the concentration of trawling effort along the borders of protected areas (Murawski et al. 2005), improved protection of deep-sea coral habitats (Hall-Spencer et al. 2009), and been used to estimate fish landings (catches brought to port and officially recorded) at higher resolutions than was previously possible from logbooks (Russo et al. 2018). Originally designed for monitoring vessel traffic and promoting navigational safety, automatic identification systems (AIS) are now also being used to examine the spatial and temporal patterns of fishing effort in both national and international waters. ...
... It is unclear whether fishers targeted these grounds for particular species, because information on the landings composition derived from the nursery areas was unavailable. However, areas directly south and east of the Jabuka/ Pomo no-trawl zone contain the highest quality nursery habitat (WebFigure 7), and they overlap with the area estimated to have the highest landings of both Norway lobster and European hake in the Adriatic Sea for the Italian fleet (Russo et al. 2018). ...
The benefits of protected areas depend on compliance, and achieving protection remains a challenge in intensely used areas where conservation and socioeconomic goals are in real or apparent conflict. One recent innovation – satellite tracking of commercial fishing vessels – has been introduced to help with ocean protection initiatives and build trust between fishers and managers. We paired vessel traffic data before and during a temporary closure in the Adriatic Sea with data on fish nursery habitat to examine changes in fishing effort and their potential consequences. Trawlers generally complied with the closure but maintained overall effort by trawling more intensely outside of the no‐trawl zone, especially near its borders and closer to shore. We detected stronger than expected fishing effort in a sub‐region within the protected area, suggesting that this location should be closely monitored for compliance. Notably, fishing effort was relocated to nursery grounds for some exploited species, illustrating the importance of understanding species’ life histories and habitat distribution in the design of protected areas.
... For the southern Adriatic Sea (GSA 18) the countries involved are Italy, Albania and Montenegro. The Pomo/Jabuka pit area comprises three depressions (> 200 m depth) in the middle of the Adriatic Sea, covering an area of approximately 2000 km2 (Russo et al., 2018). ...
FAIRSEA (ID 10046951) “Fisheries in the AdriatIc Region - a Shared Ecosystem Approach”
... The integrated analysis between VMS data and logbook data will allow fishery data to be analyzed on a spatial scale, which will be more accurate (Gerritsen & Lordan 2011). Moreover, according to Russo et al (2018), a suitable control method for a fishery logbook is to combine two primary sources of data, VMS data and vessel arrival data (whether it is loading or unloading). The data and information results can be used to reference the optimal effort in utilizing longline tuna catching units. ...
The Ministry of Marine Affairs and Fisheries (Indonesia) Regulations No. 56 and No 57 of 2014 concerning the moratorium on fishing permits and the prohibition of transshipment was issued to ameliorate illegal fishing, unreported fishing, and unregulated fishing. Tuna longline is the fishing gear affected by the regulation. Thus, many fleets are not operating, reducing tuna production in Indonesia. Business strengthening strategies need to be applied to address these problems. The approach to solve these issues regards a soft system methodology. The results showed that the dominant catches of longline tuna at Nizam Zachman Oceanic Fishing Port were bigeye (Thunnuns obesus) (27%), yellowfin (Thunnus albacares) (26%), skipjack (Katsuwonus pelamis) (12%), and albacore (Thunnus alalunga) (7%), with catchment areas in Fisheries Management Area (FMA) 572 and 573. After the policy took effect, longline tuna production decreased from 11768.267 tons in 2014 to 4636.657 tons in 2019. The frequency of vessels that land fish has also dropped, from 514 units in 2014 to 156 units in 2019. Strategies have been made based on three conceptual models. First, the Ministerial Regulation No. 58 of 2020 needs to be implemented properly. The second necessary strategy is to supervise and foster a longline tuna fishery business license through an integrated data collection system. Third, the government needs to develop sustainable longline tuna fisheries business by determining the amount of optimal effort allocation.
... For this reason, a segmentation of trawling fleet was not assumed as not relevant for the analysis. Taking into consideration the choice of fishing effort indicators, the use of spatial fishing effort data, acquired from Vessel Monitoring System (VMS) and the Automatic Identification System (AIS), are increasingly used (Russo et al., 2018). However, some critical points can arise when the study areas are not overlap to management spatial units (e.g., GSAs), which are adopted as reference for this kind of data (Russo et al., 2019). ...
A modelling approach applied to the study of ecosystems from a management and conservation point of view allows their complexity to be investigated and represents a tool for meeting sustainability goals, part of the 2030 Agenda for Sustainable Development. Tying into Sustainable Development Goals (SDGs) 13 and 14, the human activities of fisheries and climate change represent two pivotal drivers for the marine environment, acting on keystone predators, such as odontocetes. A calibrated time-dynamic model (Ecopath with Ecosim) was developed to investigate the effects on the odontocetes and their main prey in the Northern Ionian Sea (Central Mediter-ranean Sea), according to changes in trawl fishery and primary productivity. In particular, the food web of the Gulf of Taranto (GoT) is described by 51 functional groups (FGs), with four odontocetes (striped, common bottlenose, Risso's dolphin and sperm whale) represented as a single FG, and 5 fishing fleets. The calibration of the Ecosim model was carried out during the period 2009-2018 using a combination of automatic and manual fitting procedures. Changes in trawling fishing effort (increases, reductions and bans) and in primary production were tested in the period until to 2040 to detect the effect on the biomass of odontocetes and their main prey. The cumulative effects of the two drivers were assessed using an Interaction Effect Index. Fishery showed negligible effects on all odontocetes, with the exception of the common bottlenose dolphin which respond in a negative way to an increase in fishing effort. The reduction in top-predators due to fishing seems to lead to a reduction in predation pressure on meso-consumers, and thus to an increase in predation pressure on basal prey. Similarly, the bottom-up effect due to increased primary production tends to be diluted towards the top of the trophic network, with slight effects on odontocetes. The trophic interaction pattern tends to mediate the effects tested in the model with a variety of different outcomes on prey. The application of the interaction effects index could contribute to disentangling the effects of fishing and climate on the food web, providing information to address the analysis required by the SDG 14 targets.
... The Pomo/Jabuka Pits are three depressions delimited by the 200 m bathymetry located in the central Adriatic Sea ([39], Figure 1); this area is one of the main fishing grounds historically shared by the Italian and Croatian fleets [34,40]. The complex topography of the area and the Adriatic Sea oceanographic regimes make it a very particular environment in which the water exchange does not happen annually [41]. ...
Marine resources exploitation through bottom trawling affects marine ecosystems; thus, management should consider the presence of sensitive species as ecosystem health indicators. Epibenthic organisms such as sea pens are widely used to assess benthic conditions, as their populations are declining where trawling is intense. The Pomo/Jabuka Pits fishing ground in the Adriatic Sea, subject to various management measures over the years, is a nursery for European hake and hosts a small, but dense, population of Norway lobster and a remarkable abundance of pink shrimp. The sea pen Funiculina quadrangularis shares its habitat (sandy-muddy bottoms) with these crustaceans. Through UnderWater TeleVision surveys conducted from 2012 to 2019, F. quadrangularis abundance and distribution were quantified in relation to changes in the spatiotemporal distribution of fishing efforts. The average density (n/m2) of colonies was calculated for three periods: BEFORE implementation of measures (before 1 July 2015), during an INTERMEDIATE period in which limitations changed (2 July 2015 to 31 August 2017), and AFTER the implementation of a Fishery Restricted Area (from 1 September 2017). F. quadrangularis revealed an increase in density where fisheries were closed, even after a short period. This showed how management measures can positively influence epibenthic communities and that sea pens can be indicators of impact and/or recovery of habitats.
... Sufficient monitoring and control of fishing operations are also necessary to ensure that fisheries stop when critical catch limits are reached and to avoid discarding behavior. This requires a combination of different techniques including electronic logbook, VMS, acoustic survey, and observers (Mion et al. 2015;Palmer et al. 2016;Barbeaux et al. 2018;Russo et al. 2018). Despite its importance, mixed fisheries monitoring remains one of the least addressed topics in research, indicating a need for the development and evaluation of novel monitoring approaches in the future. ...
Mixed fisheries occur when multiple species are caught together and harvested by multiple fleets. The biological and technical interactions in mixed fisheries distinguish them from single-species fisheries, which makes them challenging for their assessment and management. The present knowledge synthesis reviewed pertinent policy documents and academic databases for twenty-three mixed fisheries worldwide; aiming to characterize attributes of mixed fisheries, provide overviews on their assessment and management, assess current research progress, and identify key factors that impact management effectiveness. Mixed fisheries were found to exhibit varying characteristics worldwide, rendering the implementation of universal management solutions unlikely. While mixed fisheries stock assessment and management are mostly based on single-species approaches, additional mixed fisheries considerations were incorporated at various scales, including multispecies, sector-specific, fishery, and ecosystem levels. Ecosystem-wide management considerations were the most significant contributor to improved management performance in terms of conserving stock biomass and preventing overfishing, underscoring the merits of the Ecosystem-based Fisheries Management (EBFM) principle. Mixed fisheries research demonstrated regional and thematic variations, with the most popular topics addressing immediate and practical management concerns, and the less frequently discussed topics offering valuable insights related to climate change and socio-ecological perspectives. The synthesis identified the available management approaches for mixed fisheries from different jurisdictions, yet their diversity highlighted a lack of global consensus on best management practices. Future mixed fisheries will benefit from balancing tradeoffs between ecological and socio-economic needs, implementing EBFM, adopting diverse and harmonized management tools, and prioritizing monitoring efforts.
... These data were cross-linked at the scale of single vessels in order to reconstruct the monthly activity (in terms of spatial allocation of fishing effort) and corresponding landings by species. A non-negative least square regression (Russo et al., 2018) was used to reconstruct spatial origin of these landings and to estimate the monthly value of Landings-Per-Unit-of-Effort (LPUE) by cell for the main demersal species exploited by Italian trawlers. ...
... The recent development of environmental DNA (eDNA) offers a powerful, cost-effective, noninvasive alternative (Taberlet et al., 2012;Thomsen et al., 2012), which has been shown to be effective in tracking the presence of cartilaginous fish in various environments (Bakker et al., 2017;Boussarie et al., 2018;West et al., 2021;Dunn et al., 2022;Liu et al., 2022). Spatial models are continuously developed for studying the impact of demersal fisheries, and the spatial origin of catches, using satellite-based information on fishing activities (D'Andrea et al., 2020;Russo et al., 2018Russo et al., , 2019; eDNA could enhance these models, being itself an important source of biological information. The vast expanse of the sea, however, still constitutes a barrier to the generation of species inventories at the scale and granularity that can significantly improve management practices. ...
T.R. and S.M. contributed equally to this work. § L.A. and G.M. contributed equally to this work. Conservation and management of chondrichthyans are becoming increasingly important, as many species are particularly vulnerable to fishing activities, primarily as bycatch, which leads to incomplete catch reporting, potentially hiding the impact on these organisms. Here, we aimed at implementing an eDNA metabarcoding approach to reconstruct shark and ray bycatch composition from 24 hauls of a bottom trawl fishing vessel in the central Mediterranean. eDNA samples were collected through the passive filtration of seawater by simple gauze rolls encapsulated in a probe (the "metaprobe"), which already showed great efficiency in detecting marine species from trace DNA in the environment. To improve molecular taxonomic detection, we enhanced the 12S target marker reference library by generating sequences for 14 Mediterranean chondrichthyans previously unrepresented in public repositories. DNA metabarcoding data correctly identifies almost all bycaught species and detected five additional species not present in the net, highlighting the potential of this method to detect rare species. Chondrichthyan diversity showed significant association with some key environmental variables (depth and distance from the coast) and the fishing effort, which are known to influence demersal communities. As DNA metabarcoding progressively positions itself as a staple tool for biodiversity monitoring, we expect that its melding with opportunistic, fishery-dependent surveys could reveal additional distribution features of threatened and elusive megafauna.
... The spatial productivity (monthly LPUE as grams of catch per meter of LOA and hour of fishing) was estimated using landings and VMS data, according to the procedure of Russo et al., 2018 and. At the same time, the economic parameters needed to model the relationships between 1) fishing effort and its related costs (crew salaries, fixed costs, etc.); 2) spatial fishing footprint and its related costs (i.e. ...
This publication is a Science for Policy report by the Joint Research Centre (JRC), the European Commission’s science and knowledge service. It aims to provide evidence-based scientific support to the European policymaking process. The scientific output expressed does not imply a policy position of the European
Commission. Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use that might be made of this publication. For information on the methodology and quality underlying the data used in this publication for which the source is neither Eurostat nor other Commission
services, users should contact the referenced source. The designations employed and the presentation of material on the maps do not imply the expression of any opinion whatsoever on the part of the European Union concerning the legal status of any country, territory, city or area or of its authorities, or concerning the
delimitation of its frontiers or boundaries.
... Furthermore, their integration with data from vessels' sales, or from electronic logbooks, implemented a decade ago, can provide explicit spatio-temporal information on the distribution of species-specific fishing effort and species relative abundance. Integration of VMS and catch data has been explored by several authors to estimate and map fishing effort and catch per unit of effort (CPUE), as a proxy to fish density [15][16][17][18]. ...
In this study, the fishing distribution and intensity over the Gorringe bank, a large oceanic underwater mountain located in the NE Atlantic, Natura 2000 Network MPA inside Portugal‘s EEZ is evaluated in the period from 2012 to 2016. Based on the combined analysis of fisheries-dependent data comprising Vessel Monitoring System (VMS), Automatic Identification System (AIS) and electronic logbooks available for the Portuguese fleet operating within the area, it was possible to identify fishing trips and fishing events and define fishing trajectories, allowing the estimation of the fishing effort and the CPUE at a high spatial resolution. A total of 32 Portuguese vessels were identified to have undertaken fishing activity within the limits of this MPA, mainly longliners based on mainland ports, operating drifting and bottom longlines on a seasonal basis. Fleet-related differences in the distribution and intensity of fishing effort and CPUE for the main target species were addressed. The bottom longline activity concentrated, as expected, around the two seamount summits, where the presence of VMEs and sensitive habitat-forming species have been registered. The analysis of AIS data, the only dataset made available in this study for non-Portuguese vessels, strongly suggests that the foreign fleet operating within the Gorringe MPA represents a significant fraction of the fishing activity in the area. If assessing the fishing impacts is deemed as an important objective in the management of this MPA, then the results obtained in this study can be a valuable contribution towards the environmental protection of this oceanic seamount.
... The geographically referenced fishing effort with corresponding catch landings is used to calculate catch rates, which are widely used as indicators of abundance (Russo et al., 2018). Therefore, this approach might be a reliable alternative in providing spatial information related to potential catches in the fishing ground. ...
This study aimed to evaluate the factors affecting the catch rate and
predict the potential catch for the determination of productive fishing
grounds for miter squid (Uroteuthis chinensis) in the Indonesian Fisheries
Management Area 711 for 2020. A vessel monitoring system and landing
data from 66 cast nets were used to investigate catch per unit effort. Depth,
chlorophyll-a, and sea surface temperature from satellite imagery combined
with the month and geographic location of fishing were evaluated for their
effect on catch per unit effort using a general additive model. The best model
output was employed to identify productive fishing grounds. The results
revealed that the average monthly catch rate ranged from 89.43- 337.47kg h1
, with the highest occurring in May. Three significant variables affected the
catch rate: month, latitude, and sea surface temperature, with contributions of
42.6%, 33.6%, and 12.7%, respectively. The catch rate continued to rise
from March to May and tended to increase at higher latitudes where sea
surface temperatures ranged from 27.6- 29.5°C or 31.5- 32.2°C. Based on the
monthly map of predicted potential catch, the most productive fishing
grounds were located in the waters between the islands of Anambas, Natuna,
and Tambelan. These findings can support marine spatial planning and
squid resource management in IFMA 711.
... One of the possible management measures are 'fisheries restricted areas' designed to maintain stocks and populations. A recently established fisheries restricted area in the central Adriatic Sea, the Jabuka/Pomo pit, has been recognised as a critical habitat for demersal species (in particular, hake and Norway lobster) (Russo et al., 2018) and the monitoring activities carried out in the area show the positive effects of the closure, although the fishery restricted area is too recent to have peer-reviewed impact publications on the effects yet. The Jabuka/Pomo pit is quantitatively confirmed as sound and necessary since it is the most important spawning area (with good spawning performances) in the Adriatic for Norway lobster (Melaku Canu et al., 2020). ...
This report is a narrative review of the effects reported in the scientific literature (peer-reviewed and indexed scientific publications showing quantitative evidence) about the relationships between a selection of nature restoration practices and food production. The reported effects are extracted from systematic reviews, meta-analyses and individual papers. As a narrative review, this is not a representative sample of all the available studies conducted on the topic.
Although we cannot extract a quantitative estimate without a proper meta-analysis, our review suggests that nature restoration measures have a remarkably positive impact on food productivity in the long-term, while most of the short-term impacts are context- and species-dependant. Thus, we consider that the restoration of degraded and overexploited ecosystems is an insurance policy to ensure the long-term sustainability and resilience of our food systems.
... In this way, it would be useful to further research using also an ecotoxicological perspective. Moreover, a future study could examine whether the pattern returned by the blackmouth catshark could serve as a proxy for those of other species, including key resources for fisheries, given that the samples collected during this study were taken over important fishing grounds (Russo et al. 2018). In conclusion, this study provides a contribution to knowledge on trophic ecology and on the contamination of the diet by plastic. ...
The presence of plastic waste in the marine environment has driven the scientific community to make significant efforts to study and mitigate its possible effects. One of the critical aspects is to determine if and how an increase in ingestion events may occur as a result of the accumulation of plastic waste on the seabed. In this study, G. melastomus is examined for its ability to indirectly provide information on the amount of macroplastics accumulating on the seafloor. Plastic ingestion is explored by describing the feeding habits of the species, which have the potential to provide very useful information regarding biological or ecological issues. The diet of G. melastomus mainly consisted of cephalopods, bathypelagic fishes, and decapod crustaceans, increasing in diversity during growth. The generalist-opportunistic feeding behaviour of this species leads to the incidental ingestion of plastic particles (N = 47, with a mean (± SD) of 1.47 ± 0.28 per specimen) which can be indirectly associated to the presence of macroplastics on the seafloor. Indeed, our results indicate a significant relationship between the amount of macroplastics present on the seabed and the frequency of ingestion of plastic particles by blackmouth catshark. We propose G. melastomus as an excellent candidate for developing a valid monitoring strategy for the presence of plastics on the seabed, as requested by the EU Marine Strategy Framework Directive.
... Leaving aside the oceanographic dynamics of plastic pollutants, the biomonitoring of their abundance and distribution as revealed by the analysis of stomach contents in non-commercial species, such as the blackmouth catshark, could represent an important approach to assessing the risk of contamination of sheries landings of commercial species. A future study could examine whether the pattern returned by the blackmouth catshark could serve as a proxy for those of other species, including key resources for sheries, given that the samples collected during this study were taken over important shing grounds (Russo et al. 2018). ...
The presence of plastic waste in the marine environment has driven the scientific community to make significant efforts to study and mitigate its possible effects. One of the critical aspects is to determine if and how an increase in ingestion events may occur as a result of the accumulation of plastic waste on the seabed. In this study, G. melastomus is examined for its ability to indirectly provide information on the amount of macroplastics accumulating on the seafloor. Plastic ingestion is explored by describing the feeding habits of the species, which have the potential to provide very useful information regarding biological or ecological issues. The diet of G. melastomus mainly consisted of cephalopods, bathypelagic fishes, and decapod crustaceans, increasing in diversity during growth. The generalist-opportunistic feeding behaviour of this species leads to the incidental ingestion of plastic particles (N= 47, with a mean (± SD) of 1.47 ± 0.28 per specimen) which can be indirectly associated to the presence of macroplastics on the seafloor. Indeed, our results indicate a significant relationship between the amount of macroplastics present on the seabed and the frequency of ingestion of plastic particles by blackmouth catshark. We propose G. melastomus as an excellent candidate for developing a valid monitoring strategy for the presence of plastics on the seabed, as requested by the EU Marine Strategy Framework Directive.
... Bradley et al. (2019) survey recent developments in technology that could support the modernization and expansion of fisheries data systems including for the provision of more detailed spatial data. At the same time, investigations into the integration of VMS and logbook or landings data to permit more finer-scale spatial analysis (Gerritsen and Lordan, 2011;Russo et al., 2018) and sophisticated catch reconstruction approaches (Pauly and Zeller, 2016;SPC [Pacific Community], 2021) permit analysis of historical catch data at increasing levels of spatial disaggregation. Bradley et al. (2019) point to a number of factors that currently inhibit the uptake of more technologically advanced data systems, including cost, institutional and legal barriers, and a lack of cooperation and trust in the relationship between fishers and managers. ...
The focus on flag States for the purpose of attributing fisheries catch is inconsistent with the assignment of sovereign rights to coastal States under international law and undermines equity in contemporary quota allocation negotiations. We propose modernizing reporting frameworks to include zone-based reporting of fish catches to more equitably present data, ensure consistency with the Law of the Sea, and better support the realization by developing coastal States of their development aspirations consistent with SDG 14, Life Below Water. States are already required to collect the data necessary to support this change, and many regional fisheries management authorities already do so. Reforms to data collection and reporting mechanisms should support zone-based catch attribution as a central feature of negotiations around access to future fishing opportunities on shared resources. Doing so will ensure that the sovereign rights of developing coastal States are properly accounted for and implemented.
... These data were cross-linked at the scale of single vessels in order to reconstruct the monthly activity (in terms of spatial allocation of fishing effort) and corresponding landings by species. A non-negative least square regression (Russo et al., 2018) was used to reconstruct spatial origin of these landings and to estimate the monthly value of Landings-Per-Unit-of-Effort (LPUE) by cell for the main demersal species exploited by Italian trawlers. ...
This paper presents an analysis of the effect of SARS-CoV-2 coronavirus pandemic and related restrictive measures on the activity of the Italian fleet of trawlers, which represents one of the most important fisheries in the Mediterranean Sea. We integrated multiple sources of information including: (1) Fleet activity data from Vessel Monitoring System, the most important satellite-based tracking device; (2) vessel-specific landing data disaggregated by species; (3) market and economic drivers affecting the effort variation during the lockdown and in the related fishing strategies; (4) monthly landings of demersal species in the main Italian harbors. These data sources are combined to: (1) Assess the absolute and relative changes of trawling effort in the geographical sub-areas surrounding the Italian coasts; (2) integrate and compare these changes with the market and economic drivers in order to explain the observed changes in fishing effort and strategy; (3) analyze the changes of the fishing effort on the Landing-per-unit-effort (LPUE) in order to further understand the strategy adopted by fishers during this crisis and to infer the potential consequence for the different stocks. The results provide an overview of the effects of the “COVID-19 shock,” in terms of fishing activity and socio-economic drivers, demonstrating that the consequences of the pandemic have been very varied. Although the COVID-19 shock has caused a marked overall reduction in activity in the first semester of 2020, in some cases the strategies adopted by fishermen and the commercial network linked to their activity have significantly reduced the impact of the emergency and taken back catch and effort to levels similar to those of previous years. These results could provide insights for management measures based on temporal stops of fishing activities. In particular, if no limits to the fishing effort after the restart of fishing activities are adopted, the benefits of fishing pressure reduction on fishery resources could be nullified. On the other hands, when fishing activities restart, and in the absence of catch control, effort tends to increase on coastal bottoms characterized by greater abundance of resources and longer effective fishing time.
... vessels > 15 m) operating worldwide are equipped with remote tracking devices such as the Vessel Monitoring System (VMS) and/or the Automatic Information System (AIS) (Amoroso et al., 2018;Russo et al., 2019). This offers the opportunity to reconstruct, with great spatial and temporal accuracy, the origin of landings and/or catches (Russo et al., 2018). It is therefore easy to foresee how the information provided by the 'metaprobe' could be integrated with the fishing footprint of trawlers to obtain powerful reconstruction of marine biodiversity at different scales. ...
The global need to monitor the status of marine resources is a priority task in marine management, but most ocean surveys still rely on costly and time-consuming capture-based techniques. Here we test a novel, easy-to use device to collect eDNA on board of bottom trawl fishing vessels, during normal fishing operations, quickly and easily: custom-made rolls of gauze tied to a hollow perforated spherical probe (the 'metaprobe') that placed inside the fishing net aims to gather traces of genetic material from the surrounding environment. We collected six samples from three central Tyrrhenian sites. Using an established fish-specific metabarcoding marker, we recovered over 70% of the caught species and accurately reconstructed fish assemblages typical of the different bathymetric layers considered. eDNA metabarcoding data also returned a biodiversity 'bonus' of mostly meso-pelagic species, not catchable by bottom trawls. Further investigation is needed to upscale this promising approach as a powerful tool to monitor catch composition, assess the distribution of stocks, and generally record changes in fish communities across the oceans.
... The Norway lobster stock located in this area is distinct from other Adriatic populations and is characterized by small-sized mature individuals (Froglia and Gramitto 1982;Vrgoć et al. 2004;Colella et al. 2018, Angelini et al. 2020). Furthermore, this area represents a fishing ground shared by the Italian and the Croatian fleets (Martinelli et al. 2013;Russo et al. 2018) and has been the subject of many discussions aimed at establishing there an area closed to fishery (e.g. ADRI-AMED 2008; De Juan and Lleonart 2010). ...
... Thereby, a VMS for SSF demands the development of a cost-effective platform for daily catch recording in an integrative way, including the type of gears and species captured whenever possible (e.g., D'Andrea et al., 2020;Tilley et al., 2020). This type of data could be coupled with that obtained from onboard observers, and a program of monitoring systems in the coast, thus the acquisition of explicit spatial data from the smallscale vessels (Russo et al., 2018). Studies that jointly integrate fishing methods, species, catch, and location can be merged with VMS data and allow the identification of management units (Campbell et al., 2014;Russo et al., 2015;Salas et al., 2019;Méndez-Espinoza et al., 2020). ...
In most small-scale fisheries (SSF), there is limited or null information about the distribution and spatial extent of the fishing grounds where the fleets operate, due to the lack of explicit spatial and temporal data. This information is key when addressing marine spatial planning and fisheries management programs for SSF. In addition to technical or biogeographic restrictions, environmental conditions in the area influence the way fishers operate. Making use of data from a pilot Vessel Monitoring System (VMS) project tested in a small-scale fleet in the Southeastern Gulf of Mexico (SGoM), for the first time in the region, we were able to learn what role environmental factors play in the distribution of potential fishing grounds for this fleet. We got tracking information of 1,608 daily fishing trips from vessels operating in four states using the VMS for 7 months. We used a correlative modeling approach to identify potential fishing grounds where this fleet operates along the SGoM, accounting for environmental variables. We assumed that environmental conditions can shape the spatial distribution of species targeted by this fleet and hence influence fishers’ operations. The results indicated that net primary production and sea surface temperature were the main drivers that shape the spatio-temporal potential distribution of fishing grounds in the study site. The approach employed here seems appropriated and opens an opportunity to learn more about the factors that define the spatial distribution of small-scale fleets and their potential fishing grounds.
... Furthermore, the integration of fisheries geo-referenced information with the vessel catches reported in the electronic logbook (or proxies, e.g., landings or sales notes), can provide explicit spatio-temporal information on the species relative distribution, exploitation pattern and relative abundance. Some of the applications of integrated VMS and catch data that have been investigated include the use of CPUE maps as a proxy for fish density [14][15][16][17][18]. ...
Following the implementation of the European Council EC Regulation 2016/2336, which restricts bottom trawling below 800 m for vessels capturing deep-sea fish species, the quantification and characterization of the fishing activities at those depths became essential to evaluate potential negative economic impacts. In this study, the activity of the Portuguese coastal trawlers operating at fishing grounds deeper than 800 m is characterized for the period 2005–2016, based on the analysis of VMS data and landing declarations in national ports. A total of 13 of 125 active trawlers in the coastal fleet were found to be partially engaged in deep-sea trawling, but only two units were entirely dedicated to this activity over the period in analysis. The scarlet shrimp Aristaeopsis edwardsiana was landed from 2006 onwards as the only target species at these depths. For each of these 13 vessels, the correspondence between VMS records of trajectories assigned to fishing trips, and landing registers, provided information on the spatio-temporal patterns of activity along the time period under analysis. Among fish by-catch, only in 2006 and 2007 were deep-sea species protected under Reg. 2016/2336 recorded, after which only small, occasional landings occurred. Results show that the implementation of the trawl ban does not affect the economic activity of the Portuguese coastal trawl fleet. Even if a full ban was to be implemented it would only impact the activity of two single vessels, which would have to completely redirect their fishing operations.
... 3. The Swept Area (SWA) was computed, for the case studies involving towed gears (trawling) according to Eigaard et al. (2016) and Russo et al. (2017) as follows: ...
Current fishing practices often do not allow adequate selection of species or sizes of fish, resulting in unwanted catches, subsequently discarded, with the consequent negative effects on both marine communities and fisheries profitability. The cross-analysis of density patches of potential unwanted catches and distribution of fishing effort can support the identification of spatial-temporal hot-spots in which the fishing pressure should be reduced to limit the amount of discards. The MinouwApp represents a technological and methodological framework to bring different, and structurally complex, sources of georeferenced data together into a simple visual interface aiming to interactively explore temporal ranges and areas of interest. The objective is to improve the understanding of fisheries dynamics, including discards, thus contributing to the implementation of discard management plans in a context of participative, ecosystem-based fisheries management strategies.
... After training with observed data, the binary choice model is employed to infer the targeting status for Fishing Patterns that lack a direct observation of landings. Thereafter, a non-negative least square (NNLS) model is employed to compute the LPUE (Mullen & van Stokkum, 2012;Russo et al., 2018). The coefficients of the NNLS regression are arranged in the matrix of LPUEs estimates for species s on every time interval t in every fishing ground g. ...
Overfishing or exploitation patterns with high juvenile mortalities often negatively impact demersal fish stocks. Meanwhile, the increased availability and diffusion of georeferenced information is propelling a revolution of marine spatial planning.
A spatial‐explicit approach to the management of fishing effort should protect the Essential Fish Habitats and minimize the impact of trawlers on areas where juveniles of commercial species concentrate.
The smart R package is a data‐driven model that implements the Spatially explicit bio‐economic Model for Assessing and managing demeRsal Trawl fisheries to edit and format the raw data; construct and maintain coherent datasets; to numerically and visually inspect the generated metadata; to simulate management scenarios and forecast the possible effects in terms of resources status and economic performances of the fleets.
Explicit inclusion of the spatial dimension is essential to improve the understanding of the fishery system, and to enhance the ability of management plans to improve stocks statuses.
... Map of the study area, corresponding to the principal Nephrops norvegicus' fishing grounds in the Northern-Central Adriatic Sea: area "off Ancona" (represented by crossed cells) and Pomo/Jabuka Pits area (defined by a polygon). The fishing ground "off Ancona" is modified from Russo et al. (2018), while the Pomo/ Jabuka Pits contours are defined according to the UWTV Survey monitored area (black lines represent the trawl hauls carried out during the survey). individuals (2299 females and 1842 males). ...
Norway lobster (Nephrops norvegicus) is one of the most important crustacean species in terms of landings and commercial value for the Adriatic Sea. In this zone, this stock is composed by two different subpopulations, characterised by different growth features. This study focus on the biology of individuals from the two most important fishing grounds of the area, namely the “off Ancona” area and the Pomo/Jabuka pits. The size at the onset of first maturity (SOM) for both males and females were determined by means of macroscopic techniques: gonad tissue was examined for females, whereas the relation between carapace length and appendix masculina (length and width) was investigated for males. The estimated SOMs underline the differences between these two subpopulations, even if only the relationship between the carapace length and the length of the appendix masculina of the Pomo/Jabuka pits is statistically sound. Males from the Pomo/Jabuka pits mature at carapace length (CL) between 24.33 ± 0.32 and 25.39 ± 0.81 mm, corresponding to the SOM estimated respectively from the length and the width of the appendix masculina. Estimated L50 for females is 21.14 mm CL within the Pomo/Jabuka pits and 30.83 mm CL in the “off Ancona” area. These results underline the fact that the subpopulations living in the “off Ancona” fishing ground matures at bigger length compared to that one inhabiting the Pomo/Jabuka pits. This is in line with the other analysis carried out within this study, that show the presence of larger individuals in the “off Ancona” fishing ground, whereas small individuals characterize the Pomo/Jabuka pits. These differences have to be taken into account when managing this stock.
... The identification of the spatial structure of fishing effort and fleet distributional patterns have been demonstrated especially for large-size vessels (larger than 12 m) that are electronically monitored through Vessel Monitor System (VMS). However, a great part of the fleet (90% in Mediterranean waters) was not participated due to its small size (< 12 m) (Russo et al., 2018). This is true when considering that Mediterranean coastal fisheries are traditionally small-scale operating from the vicinity of land within the 6 nautical miles of territory waters all year round (Kavadas et al., 2015). ...
The present study deals with the monitoring for a real implementation of management policies in marine en-vironments and the potential conflicts between professional and recreationalfishery in the coastal areas of theMediterranean Sea. A comprehensive database offishing effort andfisheries infringements from professionalsmall-scale and recreationalfisheries was screened to identify hotspots areas offishing pressure in the coastalzones of Ionian Sea. Mapping points showed that the number of the recorded infringements conducted both byprofessional and recreationalfishers are too low (1 and 6 recorded infringements per 104km2of vessel days peryear) and thatfishing effort, and subsequently the recorded infringements, are not evenly distributed but con-centrated on specificfishing grounds. These revealed high-risk areas prone to illegalfishing activities and areimplying problems in the implementation of thefisheries regulations rather than a low delinquency of thefishersto comply with the rules. Findings represents a step forward in applying tracking technology to the surveillanceof small-scalefishery and are crucial towards the specification of the critical zones for setting an efficient controlsystem.
... The coupling of both sources of information (VMS and e-log) represents a powerful tool for the fine-scale mapping of catch patterns (e.g. Bastardie et al. 2010;Gerritsen et al. 2012;Hintzen et al. 2012;Ducharme-Barth et al. 2018;Russo et al. 2018), which can thus inform discard reduction strategies in real time. Such an approach was taken by the Scottish "real-time closures" scheme as one part of the North Sea cod recovery program, which aimed to establish a rolling set of closures and effort-penalised areas. ...
A scavenger is an animal that feeds on dead animals (carrion) that it has not killed itself. Fisheries discards are often seen as an important food source for marine scavengers so the reduction of discards due to the Landing Obligation may affect their populations. The literature on scavenging in marine ecosystems is considerable, due to its importance in the trophic ecology of many species. Although discards undoubtedly contribute to these species’ food sources, few can be seen to be solely dependent on carrion (including discards). Ecosystem models predicted that discards contributed very little to the diet of scavengers at a regional scale. A reduction in discards through the Landing Obligation may therefore affect populations for a few species in some areas, but generally this is unlikely to be the case. But it is challenging to identify how important discards might be to scavengers, as they are taxonomically diverse and vary in the role they play in scavenging interactions.
... The big data revolution that is taking place across multiple social systems and scales holds great promise for incorporating human behavioral data into management. Fisheries in particular have seen enormous growth in the routine gathering and curating of management-relevant data, allowing analysts to measure and understand behaviors at spatial and temporal scales that were previously unthinkable (2)(3)(4). A major challenge in the brave new world of big data is how to collapse complex and burgeoning data streams into useable information. ...
Significance
Effective fisheries management is needed to rebuild overfished stocks and prevent future overfishing, and doing so requires an understanding of fishers’ behavior. We offer an approach where “big data” routinely collected by many fisheries agencies can be used in a data-driven framework to classify fishers into discrete behavioral types, refining the métier concept and facilitating the inclusion of behavioral information into near-real-time fisheries management.
... The coupling of both sources of information (VMS and e-log) represents a powerful tool for the fine-scale mapping of catch patterns (e.g. Bastardie et al. 2010;Gerritsen et al. 2012;Hintzen et al. 2012;Ducharme-Barth et al. 2018;Russo et al. 2018), which can thus inform discard reduction strategies in real time. Such an approach was taken by the Scottish "real-time closures" scheme as one part of the North Sea cod recovery program, which aimed to establish a rolling set of closures and effort-penalised areas. ...
Fisheries regulations aim to maintain fishing mortality and fishing impacts within sustainable limits. Although sustainability is in the long-term interest of fishers, the regulations themselves are usually not in the short-term interest of the individual fisher because they restrict the fisher’s economic activity. Therefore, as is the case with all regulations, the temptation exists for non-compliance and dishonest reporting. In the EU and elsewhere, top-down, complex regulations, often leading to unintended consequences, with complex and non-transparent governance-science interactions, may decrease the credibility and legitimacy of fisheries management among fishers. This, in turn, may decrease the motivation to comply and report honestly. The Landing Obligation may make things worse because following the regulation to the letter would often strongly and negatively impact the individual fishers’ economic situation. Behavioural science suggests factors that may influence compliance and honesty. Compliance is not necessarily a function of the economic benefits and costs of rule violation: compliance may be more or less, depending on intrinsic motivations. An increased level of self-decision may lead to greater buy-in to sustainable fishing practices and voluntary compliance to catch limits and the Landing Obligation. All else being equal, people in small and self-selected groups are inherently more likely to behave “prosocially”. In this chapter, some key recommendations based on behavioural science are given for changes in institutional settings that may increase voluntary compliance and sustainable fishing practices. However, transition to a system allowing for more freedom from top-down regulation, with more self-governance, may be difficult due to institutional and cultural barriers and therefore may take many years.
... The coupling of both sources of information (VMS and e-log) represents a powerful tool for the fine-scale mapping of catch patterns (e.g. Bastardie et al. 2010;Gerritsen et al. 2012;Hintzen et al. 2012;Ducharme-Barth et al. 2018;Russo et al. 2018), which can thus inform discard reduction strategies in real time. Such an approach was taken by the Scottish "real-time closures" scheme as one part of the North Sea cod recovery program, which aimed to establish a rolling set of closures and effort-penalised areas. ...
A key requirement for the successful implementation of the Landing Obligation is the need to monitor and regulate unwanted catches at sea. This issue is
particularly challenging because of the large number of vessels and trips that need to be monitored and the remoteness of vessels at sea. Several options exist in theory, ranging from patrol vessels to onboard observers and self-sampling. Increasingly though, technology is developing to provide remote Electronic Monitoring (EM) with cameras at lower costs. This chapter first provides an overall synthesis of the pro’s and con’s of several monitoring tools and technologies. Four EM technologies already trialled in EU fisheries are then summarised. We conclude that it is now possible to conduct reliable and cost-effective monitoring of unwanted catches at sea, especially if various options are used in combination. However, effective monitoring is a necessary condition for the successful implementation of the Landing Obligation but insufficient unless it is implemented with a high level of coverage and with the support of the fishing industry.
... The coupling of both sources of information (VMS and e-log) represents a powerful tool for the fine-scale mapping of catch patterns (e.g. Bastardie et al. 2010;Gerritsen et al. 2012;Hintzen et al. 2012;Ducharme-Barth et al. 2018;Russo et al. 2018), which can thus inform discard reduction strategies in real time. Such an approach was taken by the Scottish "real-time closures" scheme as one part of the North Sea cod recovery program, which aimed to establish a rolling set of closures and effort-penalised areas. ...
While genetics has assisted fisheries management for over 50 years, genetic applications aiming to alleviate or eliminate discards have received little attention. In this chapter, we focus on how genetics can be applied under the EU Landing Obligation, to identify and prevent unwanted catches and to estimate the composition of products made from such catches. Three themes are covered: (i) the genetic identification of bycatch; (ii) the genetic analysis of species composition in nutritional products made from unwanted fish; (iii) the potential of using so-called environmental DNA (DNA shedded from aquatic organisms into the water) to reduce bycatch. For all themes, we introduce and explain the relevant genetic techniques, including data formats and analyses. We present the most significant limitations of the methodologies for their implementation in fisheries and provide examples of their use through relevant case studies. Finally, we discuss the potential future perspectives, with emphasis on the rapid progress in portable and automatic DNA devices, which may revolutionize the use of real-time onsite genetic analyses.
... The coupling of both sources of information (VMS and e-log) represents a powerful tool for the fine-scale mapping of catch patterns (e.g. Bastardie et al. 2010;Gerritsen et al. 2012;Hintzen et al. 2012;Ducharme-Barth et al. 2018;Russo et al. 2018), which can thus inform discard reduction strategies in real time. Such an approach was taken by the Scottish "real-time closures" scheme as one part of the North Sea cod recovery program, which aimed to establish a rolling set of closures and effort-penalised areas. ...
The European Common Fisheries Policy (CFP) has established a landing obligation (LO) and the need for proper management of bycatches without incentivising their capture. Food use is the priority option but only unwanted catches (UWC) above minimum conservation reference size (MCRS) can be used for direct human consumption. As a result, other options, such as animal feeds, industrial uses or energy, should be considered to valorise landed < MCRS individuals. Two approaches have been developed to help select the best available option for processing UWC. The first methodology is based on a multi-criteria decision analysis (MCDA) using an analytic hierarchy process (AHP) that considers technical, economic and market criteria. As a sample case, we chose the Basque fleet fishing in the Bay of Biscay, developed within the H2020 DiscardLess project. The second approach is based on the simultaneous analysis of both economic and environmental aspects. This was applied to the case of Spanish bottom trawlers operating in ICES sub-Divisions VIIIc and IXa. Finally, various food products and bio compounds from typical UWC biomass were obtained in a pilot food processing plant developed within the LIFE iSEAS project.Keywordsε-constraint approachAnalytic hierarchy processBiomoleculesBiorefineryBycatchesDiscards management
In-land management
Landing obligationMulti-criteria decision analysisUnwanted catchesValorisation
... The coupling of both sources of information (VMS and e-log) represents a powerful tool for the fine-scale mapping of catch patterns (e.g. Bastardie et al. 2010;Gerritsen et al. 2012;Hintzen et al. 2012;Ducharme-Barth et al. 2018;Russo et al. 2018), which can thus inform discard reduction strategies in real time. Such an approach was taken by the Scottish "real-time closures" scheme as one part of the North Sea cod recovery program, which aimed to establish a rolling set of closures and effort-penalised areas. ...
This chapter deals with the development of the European Union (EU) discard policy over time. It describes the process from 1992, when the issue of discards was first recognised in the Common Fisheries Policy (CFP) reform process, to the Landing Obligation (LO) adopted in 2013. It analyses the context to which policy choices were made that shaped the present format of the EU LO, how it is being implemented and the impact it is having on associated fisheries management measures. Finally, future possible policy developments are examined.
A large fraction of costs in wild fisheries are fuel related, and while much of the costs are related to gear used and stock targeted, search for fishing grounds also contributes to fuel costs. Lack of knowledge on the spatial abundance of stocks during the fishing season is a limiting factor for fishing vessels when searching for suitable fishing grounds, and with better planning and routing, costs can be reduced. Strategic and tactical decision-making can be improved through operational decision support tools informed by real-time data and knowledge generated from research. In this article, we present a model-based estimation approach for predicting catch potential of ocean areas. An individual-based model of herring migrations is combined with an estimation approach known as Data Assimilation, which corrects model states using incoming data sources. The data used to correct the model are synthetic measurements generated from neural network output. Input to the neural network was vessel activity data of over 100 fishing vessels from 2015-2018, targeting mainly herring. The output is the predicted normalized density of herring in discrete grid cells. Model predictions are improved through assimilation of synthetic measurements with model states. Characterizing patterns from model output provides novel information on catch potential which can inform fishing activity.
Mapping the economic value of the ocean is pivotal to understand how marine ecosystems contribute to human wellbeing and to support fisheries management. We present a framework to analyse fisheries data and map fishing revenues by linking Vessel Monitoring System (VMS) information to logbooks and observer data. We provide a detailed step-by step methodology and describe different approaches available to fulfill each step, with special notes for the processing of real world messy data. The framework consists of six processing steps: (1) identifying the target fishery and subsetting VMS data; (2) extracting relevant variables; (3) linking observer and VMS data; (4) identifying fishing activity; (5) linking VMS and logbook data; (6) extracting derived variables and mapping revenue back to the communities that extracted the resources. Building this framework opens a broad range of applications including marine spatial planning, rapid response analyses, high-resolution stock assessments and spatially explicit-socioeconomic analyses. We demonstrate the framework in the reef fishery of the Gulf of Mexico, where spatial planning for aquaculture is currently underway.
In this study, we aimed to examine the status and historical change of trawl fishing fleet in the Foça in the Aegean Sea. The data of the study representing all actively working trawlers in 1998-1999 and 2019 were collected through face-to-face interviews with trawler boat owners in Foca. The questionnaire consisted of questions related to the characteristics of the vessels, fishing activity, socio-demographics of fishers, running costs, annual landings of species and management issues. The study indicated that the annual landings of the main target species significantly decreased over the last two decades. Fishers reported the landings of some species including Dentex gibbosus, Dentex macrophthalmus, Homarus gammarus, Mustelus mustelus, Octopus vulgaris, Parapenaus longirostris, Scomber colias, Scorpaena porcus, Scorpaena scrofa, Spicara smaris, Trachurus spp. and Zeus faber decreased considerably over this period. Over the same period, a decrease was found in the mean length of Merluccius merluccius, Lophius piscatorius and Zeus faber. The vessels’ fuel tank volume and tow duration showed significant increases from 1999 to 2019. The trawl fleet decreased by ~75% from 1999 to 2019 and 55% of the current fishers reported that they may leave the fishery sector within the next 10 years. A change was also determined in the tradition of the sharing system, which is the number of crews paid in shares rather than a fixed salary, significantly decreased. Moreover, the crew numbers from vessel owners’ households significantly decreased. As a result, we discussed the changes, problems, regulations and restrictions related to trawl fishery in Foça, which used to be the most important trawling fishing center of the Aegean twenty years ago. We found dramatic changes in many aspects compared to what it was two decades ago and provided suggestions regarding fisheries management.
Fishing logbook records the fishing behaviors and other information of fishing vessels. However, the accuracy of the recorded information is often difficult to guarantee due to the misreport and concealment. The fishing vessel monitoring system (VMS) can monitor and record the navigation information of fishing vessels in real time, and it may be used to improve the accuracy of identifying the state of fishing vessels. If the VMS data and fishing logbook are combined to establish their relationships, then the navigation characteristics and fishing behavior of fishing vessels can be more accurately identified. Therefore, first, a method for determining the state of VMS data points using fishing log data was proposed. Secondly, the relationship between VMS data and the different states of fishing vessels was further explored. Thirdly, the state of the fishing vessel was predicted using VMS data by building machine learning models. The speed, heading, longitude, latitude, and time as features from the VMS data were extracted by matching the VMS and logbook data of three single otter trawl vessels from September 2012 to January 2013, and four machine learning models were established, i.e., Random Forest (RF), Adaptive Boosting (AdaBoost), K-Nearest Neighbor (KNN), and Gradient Boosting Decision Tree (GBDT) to predict the behavior of fishing vessels. The prediction performances of the models were evaluated by using normalized confusion matrix and receiver operator characteristic curve. Results show that the importance rankings of spatial (longitude and latitude) and time features were higher than those of speed and heading. The prediction performances of the RF and AdaBoost models were higher than those of the KNN and GBDT models. RF model showed the highest prediction performance for fishing state. Meanwhile, AdaBoost model exhibited the highest prediction performance for non-fishing state. This study offered a technical basis for judging the navigation characteristics of fishing vessels, which improved the algorithm for judging the behavior of fishing vessels based on VMS data, enhanced the prediction accuracy, and upgraded the fishery management being more scientific and efficient.
The Working Group on Fisheries Benthic Impact and Trade-offs (WGFBIT) develops methods
and performs assessments to evaluate benthic impact from fisheries at regional scale, while con-
sidering fisheries and seabed impact trade-offs.
In this report, new fishery benthic impact assessments (ToR A) are shown out for several sub-
regions in (French Mediterranean, Celtic Seas). For other regions, updates of the whole assess-
ment or specific steps only were presented.
To further standardise the different components of the WGFBIT approach across all (sub-)re-
gional assessments, a more detail overview of those components was compiled. These compo-
nents were slightly different among those regions, related to variation in data availability, envi-
ronmental characteristics and implementation possibilities among the (sub-)regions.
In WGFBIT, assessments are sometimes based on trawl or grab data, which are sampling differ-
ent components of the seafloor ecosystem and can have consequences on the created sensitivity
layer. Therefore, there is looked in more detail how the sensitivity outcome (and layers) can dif-
fer due to the use of benthic data gathered with different gears (grab/core, trawl or video). The
preliminary comparability analyses are performed on different levels: (1) based on co-located
sampling; (2) comparing sensitivity maps of the (sub-) area, based on different gears. There were
differences observed in longevity distribution at locations sampled with different gears and dif-
ferences in data and models lead also to differences in the sensitivity layers.
The WGFBIT seafloor assessment framework is not the only way to assess benthic impacts from
physical disturbance. A discussion session was held on how the future workflow on advice that
ICES WGFBIT assessment contribute to, will be organized.
Marine sediments harbour significant levels of biodiversity that play a key role in ecosystem
functions and services such as biogeochemical cycling, carbon storage and the regulation of cli-
mate. Through the removal of fauna, changes in physico-chemical nature and resuspension of
sediment, bottom trawling may result in significant changes in the ecosystem functioning of shelf
seas. An assumption of the current PD model is that high community biomass implies higher
ecosystem functioning. However, total community biomass does not necessarily reflect changes
in species and functional trait composition which play a key role in regulating ecosystem func-
tions. ToR D is working on an improved understanding of the link between species functional
effect traits and proxies and processes for specific ecosystem functions to improve our ability to
predict the impact of fishing disturbance on benthic ecosystem functioning more accurately.
Links between species traits and biogeochemical parameters and the impact of trawling on these
links are being explored using multivariate ordination analyses using different fauna and bioge-
ochemical datasets collected in the North Sea, Celtic Sea, Kattegat, Baltic Sea and the eastern
Mediterranean. Changes due to trawling in the trajectories of species densities over time and the
concurrent changes in the bioturbation and bioirrigation potential of communities are being
modelled using a combination of data-driven mechanistic model and a biogeochemical model.
We report on the different data analysis methods that ToR D members have developed over the
last year.
The Norway lobster, Nephrops norvegicus, supports a key European fishery. Stock assessments for this species are mostly based on trawling and UnderWater TeleVision (UWTV) surveys. However, N. norvegicus are Frontiers in Marine Science burrowing organisms and these survey methods are unable to sample or observe individuals in their burrows. To account for this, UWTV surveys generally assume that "1 burrow system = 1 animal", due to the territorial behavior of N. norvegicus. Nevertheless, this assumption still requires in-situ validation. Here, we outline how to improve the accuracy of current stock assessments for N. norvegicus with novel ecological monitoring technologies, including: robotic fixed and mobile camera-platforms, telemetry, environmental DNA (eDNA), and Artificial Intelligence (AI). First, we outline the present status and threat for overexploitation in N. norvegicus stocks. Then, we discuss how the burrowing behavior of N. norvegicus biases current stock assessment methods. We propose that state-of-the-art stationary and mobile robotic platforms endowed with innovative sensors and complemented with AI tools could be used to count both animals and burrows systems in-situ, as well as to provide key insights into burrowing behavior. Next, we illustrate how multiparametric monitoring can be incorporated into assessments of physiology and burrowing behavior. Finally, we develop a flowchart for the appropriate treatment of multiparametric biological and environmental data required to improve current stock assessment methods.
Norway lobster Nephrops norvegicus is one of the most important commercial species in the Mediterranean. This study focused on its feeding ecology in an important fishing ground within the Adriatic Sea, using an integrated approach of stomach content (SCA) and stable isotope (SIA) analyses. The simultaneous use of these tools represents a modern and complete approach that provides reliable data over time and reflects the feeding strategy of the analysed species. Monthly sampling was carried out (January-December 2019, July and October 2020; 589 specimens) to investigate seasonal changes in diet and trophic level. Variations in fullness, gonadosomatic and hepatosomatic indices were analysed to explore changes in feeding and variations in energy requirements linked to reproductive needs. Results showed that N. norvegicus mostly prey on decapod crustaceans and fish. Seasonal variations in prey consumption were likely linked to the reproductive patterns of the species. SIA results confirmed SCA findings and placed N. norvegicus at a high position within the benthic food web. Overall, considering that the Adriatic Sea represents one of the most important and productive fishing areas for Norway lobster, this study provides critical information for an effective ecosystem approach to fisheries management of this resource.
This paper presents a characterisation of the fishing fleet operating in Campania, one of the twenty administrative Regions of Italy. An analysis of the contribution of the regional fleet to the national fishing capacity is also provided.. The fleet is characterised according to its technical features (number of vessels, tonnage, engine power, length over all and fishing technique). The geographical distribution of Campanian vessels is also reported, thus highlighting the areas with the greatest importance for the fishery as well as those characterised by a predominant fishing technique. Also, the paper compares the results for the year 2018 with those of the previous years, thus offering an analysis of the trends followed by the Campanian fishing fleet in terms of the number of vessels, GT and kW. The results show that the regional fleet has lost one third of its size in nearly twenty years. Local fleet trends are set side by side with the evolution of the national, European and Mediterranean fleets. Finally, the study compares the evolution of capacity indicators with landing data of the fishery, showing that the capacity reduction caused by both management and market forces has not generated any tangible benefit to the targeted stocks and associated fisheries landings so far.
The presence of invasive species in the Mediterranean Sea is much higher than in other European seas, and understanding the reasons behind the range expansion of this invasive species is important for minimising any possible impacts to the already highly pressurised Mediterranean marine ecosystem. In this work, a brief description of sightings of the invasive lionfish Pterois miles (Bennett, 1828) in the Ionian Sea is provided, and a broad analysis of temperature patterns throughout the region is given to strengthen the understanding of lionfish range expansion in the Ionian Sea. As of 2018, lionfish expansion into the Ionian Sea was relatively abated, however a substantial increase in the temperature of the upper layers of the Eastern Mediterranean occurred during the late spring of 2018 and likely contributed towards the northward spread of this thermophilic species in the Ionian during 2019. Combining in-situ observations, CMEMS products, and citizen science data could assist in the monitoring of the range of this invasive species; a legal requirement for European countries under the Marine Strategy Framework Directive (Commission Decision (EU) 2017/848).
The original marine fisheries catch reconstructions for all countries and territories (or islands) surrounding the Mediterranean Sea for the years 1950 to 2010 were here updated for most entities to 2015, 2016 or 2017, then carried forward to 2018 using statistics from the Food and Agriculture Organization of the United Nations (FAO). The exceptions are Greece, Spain (mainland), and Turkey, whose reconstruction updates are documented elsewhere in this report. The methods applied for each catch reconstruction update, mainly derived from the previous catch reconstruction(s) for the country or territory in question, are presented in specific sections, jointly with any additional dataset. The resulting catch trends for the Mediterranean Sea as a whole are briefly discussed.
The new Common Fisheries Policy (CFP) is designed to represent an appropriate response to the uncertainties and challenges facing the fisheries sector. It also adopts a holistic approach to fisheries management, considering all factors driving fishers' behavior, and ultimately, the long-term maintenance of living resources. The most reliable way to pursue these aims could be represented by a change in the exploitation pattern, in order to guarantee the sustainability of fisheries without compromising their socioeconomic viability. In this paper, the demersal fisheries of the Ionian Sea [Geographic Sub-area (GSA) 19] were analyzed with respect to their spatial, temporal, economic, and biological characteristics in terms of four key species for fisheries, namely European hake, red mullet, giant red shrimp, and deep-water rose shrimp. Specifically, (1) a quantitative procedure was applied to break down the whole system (including small-scale fleet components) into a series of fishing grounds using input data about fishing efforts; (2) the different fleet segments were defined as a combination of main gear and fishing grounds; (3) the effort and production by fleet segment were derived according to biological samplings of commercial data (Data Collection Framework for the collection and management of fisheries data, DCF), information on localization of nursery and spawning grounds, and expert knowledge; and (4) all this information was used to feed a bioeconomic modeling tool (BEMTOOL), and to explore alternative exploitation patterns. A series of scenarios including the status quo were defined, starting from the actual management approach based on temporal fishing closure. The results showed that significant improvements in the exploitation pattern could be achieved by setting up spatial and/or temporal gear-specific bans of the fishing activity. More specifically, scenarios based on a 3-month fishing ban for trawlers are expected to provide high rebuilding of the spawning stock biomass (SSB) for all target stocks, and at the same time, result in a remarkable reduction of discards. When combined with a seasonal fishing ban for small-scale fleets equipped with nets and longlines, this approach could lead to a significant improvement in all indicators, but especially the SSB of the exploited species.
Gerritsen, H. D., Minto, C., and Lordan, C. 2013. How much of the seabed is impacted by mobile fishing gear? Absolute estimates from Vessel Monitoring System (VMS) point data. – ICES Journal of Marine Science, 70: 523–531.
Demersal trawling impacts extensively on the seabed, and the extent and frequency of this impact can be assessed using Vessel Monitoring System (VMS) data (positional data of fishing vessels). Existing approaches interpolate fishing tracks from consecutive VMS locations (track interpolation) and/or aggregate VMS point data in a spatial grid (point summation). Track interpolation can be quite inaccurate with the current 2-hour time interval between VMS records, leading to biased estimates. Point summation approaches currently only produce relative estimates of impact and are highly sensitive to the grid size chosen. We propose an approach that provides absolute estimates of trawling impact from point data and is not sensitive to an arbitrary choice of grid-cell size. The method involves applying a nested grid and estimating the swept area (area covered by fishing gear) for each VMS point. We show that the ratio of the swept area to the surface area of a cell can be related to the proportion of the seabed that was impacted by the gear a given number of times. We validate the accuracy of this swept-area ratio approach using known vessel tracks and apply the method to international VMS data in the Celtic Sea.
Gerritsen, H., and Lordan, C. 2011. Integrating vessel monitoring systems (VMS) data with daily catch data from logbooks to explore the spatial distribution of catch and effort at high resolution. – ICES Journal of Marine Science, 68: 245–252.
Vessel monitoring systems (VMS) automatically collect positional data from fishing vessels, and the data can be linked to catch data from logbooks to provide a census of spatially resolved catch-and-effort data. The most appropriate and practical method for integrating Irish VMS and logbook data is explored and validated. A simple speed rule is applied to identify VMS records that correspond to fishing activity. The VMS data are then integrated with the catch data from logbooks using date and vessel identifier. Several assumptions were investigated, and the resulting distribution maps of catch and effort appear to be unbiased. The method is illustrated with an example of a time-series of spatially explicit estimates of catch per unit effort. The proposed method is relatively simple and does not require specialist software or computationally intensive methods. It will be possible to generalize this approach to similar datasets that are available within the EU and many other regions. Analysis of integrated VMS and logbook data will allow fisheries data to be analysed on a considerably finer spatial scale than was possible previously, opening up a range of potential applications.
Reid, D. G., Graham, N., Rihan, D. J., Kelly, E., Gatt, I. R., Griffin, F., Gerritsen, H. D., and Kynoch, R. J. 2011. Do big
boats tow big nets? – ICES Journal of Marine Science, 68: 1663–1669.
Fishing vessel capacity for trawlers is generally expressed in terms of length, tonnage, and engine power, assuming that a
larger vessel has a greater fishing power. Management uses effort-control measures such as kW-day limits based on this assumption.
Many studies have shown a weak and noisy relationship between effort and modelled catches, and explanatory models often require
the inclusion of a skipper or vessel effect to explain the variance. A key element in this effect is the choice of gear size.
Relationships are investigated between metrics of the vessel (length, tonnage, and power) and the gear towed (length of groundgear,
or circumference of the net opening) in Scottish and Irish whitefish, Nephrops, and pelagic otter trawlers. Often, the vessel size did not correlate with that of the gear, or did so only for smaller vessels
(<1000 hp). The key implication is that effort management based on vessel metrics alone is not appropriate, because it is
a poor predictor for gear size, and hence for fishing power. Effort restrictions may actually encourage the adoption of larger
gears for a given vessel, to maximize the value of a limited-time resource.
VMSbase is an R package devised to manage, process and visualize information about fishing vessels activity (provided by the vessel monitoring system - VMS) and catches/landings (as reported in the logbooks). VMSbase is primarily conceived to be user-friendly; to this end, a suite of state-of-the-art analyses is accessible via a graphical interface. In addition, the package uses a database platform allowing large datasets to be stored, managed and processed vey efficiently. Methodologies include data cleaning, that is removal of redundant or evidently erroneous records, and data enhancing, that is interpolation and merging with external data sources. In particular, VMSbase is able to estimate sea bottom depth for single VMS pings using an on-line connection to the National Oceanic and Atmospheric Administration (NOAA) database. It also allows VMS pings to be assigned to whatever geographic partitioning has been selected by users. Standard analyses comprise: 1) métier identification (using a modified CLARA clustering approach on Logbook data or Artificial Neural Networks on VMS data); 2) linkage between VMS and Logbook records, with the former organized into fishing trips; 3) discrimination between steaming and fishing points; 4) computation of spatial effort with respect to user-selected grids; 5) calculation of standard fishing effort indicators within Data Collection Framework; 6) a variety of mapping tools, including an interface for Google viewer; 7) estimation of trawled area. Here we report a sample workflow for the accessory sample datasets (available with the package) in order to explore the potentialities of VMSbase. In addition, the results of some performance tests on two large datasets (1×105 and 1×106 VMS signals, respectively) are reported to inform about the time required for the analyses. The results, although merely illustrative, indicate that VMSbase can represent a step forward in extracting and enhancing information from VMS/logbook data for fisheries studies.
We previously developed an individual-based model evaluating the bio-economic efficiency of fishing vessel movements from recent high resolution spatial fishery data. The assumption was constant underlying resource availability. Now, an advanced version considers the underlying size-based dynamics of the targeted stocks for Danish and German vessels harvesting the North Sea and Baltic Sea fish stocks. The stochastic fishing process is specific to the vessel catching power and to the encountered population abundances, based on disaggregated research survey data. The impact of the effort displacement on the fish stocks and the vessels’ economic consequences were evaluated by simulating individual choices of vessel speed, fishing grounds, and ports. Some scenarios led to increased energy efficiency and profit while others such as fishing closures or fishermen optimization sometimes lowered the revenue by altering the spatiotemporal effort allocation. On an individual scale, the simulations led to gains and losses due to either the interactions between vessels or to the alteration of individual patterns. We demonstrate that integrating the spatial activity of vessels and fish abundance dynamics allow for more realistic predictions of fishermen behaviour, profits, and stock abundance.
Management of catches, effort and exploitation pattern are considered the most effective measures to control fishing mortality and ultimately ensure productivity and sustainability of fisheries. Despite the growing concerns about the spatial dimension of fisheries, the distribution of resources and fishing effort in space is seldom considered in assessment and management processes. Here we propose SMART (Spatial MAnagement of demersal Resources for Trawl fisheries), a tool for assessing bio-economic feedback in different management scenarios. SMART combines information from different tasks gathered within the European Data Collection Framework on fisheries and is composed of: 1) spatial models of fishing effort, environmental characteristics and distribution of demersal resources; 2) an Artificial Neural Network which captures the relationships among these aspects in a spatially explicit way and uses them to predict resources abundances; 3) a deterministic module which analyzes the size structure of catches and the associated revenues, according to different spatially-based management scenarios. SMART is applied to demersal fishery in the Strait of Sicily, one of the most productive fisheries of the Mediterranean Sea. Three of the main target species are used as proxies for the whole range exploited by trawlers. After training, SMART is used to evaluate different management scenarios, including spatial closures, using a simulation approach that mimics the recent exploitation patterns. Results evidence good model performance, with a noteworthy coherence and reliability of outputs for the different components. Among others, the main finding is that a partial improvement in resource conditions can be achieved by means of nursery closures, even if the overall fishing effort in the area remains stable. Accordingly, a series of strategically designed areas of trawling closures could significantly improve the resource conditions of demersal fisheries in the Strait of Sicily, also supporting sustainable economic returns for fishermen if not applied simultaneously for different species.
Deepwater fish populations are often characterized by their life-history as being highly susceptible to overexploitation. Moreover, dependent fisheries often develop rapidly, so overexploitation may occur before resource dynamics are quantified sufficiently to assess safe biological limits. It is therefore crucial to employ assessment methods that make the best use of limited data and management procedures that account for large uncertainties. This review provides a critical synthesis of assessment and management approaches for deepwater fisheries. Given limitations in the data, it is clear that assessments are likely to benefit from the application of derived relationships between life-history characteristics and the sharing of this and other information across stocks. It is important that uncertainty in assessment results is represented adequately, and management methods must in turn ensure that decision mechanisms are robust to an incomplete picture of resource dynamics. This requires construction and testing of harvest control rules within a simulation framework. Harvest control rules themselves, however, need not be complicated, and simple empirical approaches can be adequate for situations in which only relative changes in biomass can be discerned from the data. Development and testing of these control rules is likely to prove a productive area of future research.
Different age classes do not generally experience the same rates of fishing mortality. The processes resulting in age- (or length-) selection operate at several scales. At the broadest scale, population-selection measures the age-specific probability of capture, while at the finest scale contact-selection describes the vulnerability of fish that encounter the fishing gear. Population-selectivity is the process most relevant to fish population dynamics and stock assessment, but it has received far less attention than processes operating at gear-specific scales. Despite wide recognition of the diverse shapes possible for population-selectivity, the processes determining these shapes are poorly understood. This paper develops a reasonably simple model of population-selectivity from a set of survival equations, coupled to allow movement between subpopulations, and explores the conditions necessary to produce different shaped population-selection curves. Important factors influencing the population-selectivity model are the gear-specific selection characteristics of the fleets, their effort levels relative to one another, the spatial distribution of fishing mortality, and the movement of fish between subpopulations. The model can generate quite complicated curves and has surprising properties. For example, under a wide variety of conditions, even though the same asymptotic gear-selectivity applies in all subpopulations, the overall population-selectivity will be dome-shaped unless fishing mortality is uniform across all subpopulations.
In Mediterranean European countries, 85% of the assessed stocks are currently
overfished compared to a maximum sustainable yield reference value (MSY) while
populations of many commercial species are characterized by truncated size- and
age-structures. Rebuilding the size- and age-structure of exploited populations is a
management objective that combines single species targets such as MSY with
specific goals of the ecosystem approach to fisheries management (EAF), preserving
community size-structure and the ecological role of different species. Here, we show
that under the current fishing regime, stock productivity and fleet profitability are
generally impaired by a combination of high fishing mortality and inadequate
selectivity patterns. For most of the stocks analysed, a simple reduction in the
current fishing mortality (Fcur) towards an MSY reference value (FMSY), without
any change in the fishing selectivity, will allow neither stock biomass nor fisheries
yield and revenue to be maximized. On the contrary, management targets can be
achieved only through a radical change in fisheries selectivity. Shifting the size of
first capture towards the size at which fish cohorts achieve their maximum biomass,
the so-called optimal length, would produce on average between two and three
times higher economic yields and much higher biomass at sea for the exploited
stocks. Moreover, it would contribute to restore marine ecosystem structure and
resilience to enhance ecosystem services such as reservoirs of biodiversity and
functioning food webs.
Lambert, G. I., Hiddink, J. G., Hintzen, N. T., Hinz, H., Kaiser, M. J., Murray, L. G., and Jennings, S. 2012. Implications of using alternative methods of vessel monitoring system (VMS) data analysis to describe fishing activities and impacts. – ICES Journal of Marine Science, 69: 682–693.
Understanding the spatial distribution and intensity of fishing activity is a prerequisite for estimating fishing impacts on seabed biota and habitats. Vessel monitoring system data provide information on fishing activity at large spatial scales. However, successive position records can be too infrequent to describe the complex movements fishing vessels make. High-frequency position data were collected to evaluate how polling frequency and the method of analysis influenced the estimates of fishing impact on the seabed and associated epifaunal communities. Comparisons of known positions with predictions from track interpolation revealed that the performance of interpolation depended on fleet behaviour. Descriptions and indicators of fishing intensity were influenced significantly by the analytical methods (track reconstruction, density of position records) and grid-cell resolution used for the analysis. These factors can lead to an underestimation of fishing impact on epifaunal communities. It is necessary to correct for such errors to quantify the effects of fishing on various ecosystem components and hence to inform ecosystem-based management. Polling at intervals of 30 min would provide a desirable compromise between achieving precise estimates of fishing impacts on the seabed and minimizing the cost of data collection and handling.
Time/area closures have been widely used in fisheries management to prevent overfishing and the destruction of marine biodiversity. To a lesser degree, such spatio-temporal management measures have been used to reduce by-catch of finfish or protected species. However, as ecosystem-based management approaches are employed and more fisheries are managed through multispecies, multiobjective models, the management of by-catch will likely become increasingly important. The elimination of by-catch has become a primary goal of the fishing policies of many countries. It is particularly relevant in the United States, as the deadline for setting annual catch limits (ACLs) in all fisheries passes in 2011. This will result in a dramatic expansion of the number of catch and by-catch quotas. Such catch measures may result in the early closure of otherwise sustainable fisheries when by-catch quotas are exceeded. To prevent such closures and the consequent economic hardship to fishers and the economy, it is imperative that managers be given the tools necessary to reduce by-catch and improve fishing selectivity. Targeted spatio-temporal fishery closures are one solution open to managers. Here, we examine how the spatio-temporal and oceanographic characteristics of by-catch may be used by managers to design fishery closures, and place these methods within a decision tree to assist managers to identify appropriate management measures. We argue that the Correspondence:
Marchal, P. 2008. A comparative analysis of métiers and catch profiles for some French demersal and pelagic fleets. – ICES Journal of Marine Science, 65: 674–686.
A quantitative comparison between métiers and resulting catch profiles was carried out for seven French demersal and pelagic fleets operating in the North Sea, the eastern Channel, and the Bay of Biscay. Typologies for four métiers have been attempted, based on different factors (gear, mesh size, fishing ground, and/or a priori target species), data sources (logbooks or harbour enquiries), and aggregation levels. Catch profiles were selected through cluster analysis. The linkage between métiers and catch profiles was quantified using uncertainty coefficients, which depended on the métier typology being used and the fleet under consideration, but were not subject to substantial inter- or intra-annual fluctuations. Future catch profiles and métiers were forecast in 2005 based on the 2001–2004 métier/catch profile correlations. When contrasted with the 2005 observations, the forecasting score was greatest (80–85%) for pelagic trawlers and gillnetters, and lowest for demersal trawlers (5–60%).
Effective management of fishing capacity requires reliable estimates of current capacity, and to this end most countries have developed a form of capacity measure usually based on some physical characteristics of the fleet. In the United Kingdom, the "capacity" measurement system currently in place is used as the basis of existing capacity reduction programmes. Each vessel has a number of Vessel Capacity Units (VCUs) defined by its size and engine power. An assumption is made that this measure is related to the ability of the fleet to catch fish. More recently, techniques have been developed to measure capacity directly in terms of potential output. In this paper, the fishing capacity of a sample of UK otter trawlers and a set of boats that primarily use static gear (i.e. nets and lines) is estimated using data envelopment analysis (DEA). Estimates are made on a species-by-species basis for the key species harvested. These are compared to the existing measures of physical capacity. The results suggest that VCUs may provide a reasonable approximation of fishing capacity for fleets using mobile gear, but may be inappropriate for fleets using static gear. Implications for capacity management based on the physical measures, given the results, are drawn.
Logbook data constitute a key element within the electronic recording and reporting system of the European Fisheries Control Technologies Framework and are used to record, report, process, store and send information about fishing operations, including landings and fishing gear. A relevant application of logbook data is to account for the heterogeneity of fishing practices (e.g., by gear or métier), which is a key aspect of the Common Fishery Policy. However, despite their importance, few published studies have explored the potential and pitfalls of logbook data, even in combination with other powerful data sources such as the Vessel Monitoring System (VMS). Here, a new approach to characterizing the composition of landings for the different types of gear based on the use of Self-Organizing Maps (SOMs - a particular type of Artificial Neural Network) is applied to the Italian fleet logbook dataset. The SOM is trained on the landings composition and the resulting patterns are interpreted using some measures obtained from the analysis of the corresponding VMS data. Namely, the mean sea bottom depth and the area of activity are obtained for each fishing trip. Moreover, the ability of the trained SOM to predict gear from landings is tested using a new dataset. The trained SOM classifies logbook records according to the ecological, taxonomical, and trophic characteristics of the species caught, and the depth of fishing activities plays an important role in diversifying the landings associated with certain widely used fishing gear such as the bottom otter trawl. The clustering of SOM units allows the identification of a set of 12 groups, which are strongly related to the types of gear used by the Italian fleet. Furthermore, the trained SOM shows a high ability to recognize gear from logbook data, thus confirming the robustness of the landings profiles detected.
Reduction of complexity and capacity to evaluate management strategies are important considerations when modelling complex ecosystems. Models of Intermediate Complexity for Ecosystem assessments (MICE) achieve this by representing interactions among a restricted number of crucial species in the ecosystem considered. MICE applications are question-driven, heavily dependent on available data for conditioning and aimed at addressing tactical issues. Here we present the development of a MICE for the central Adriatic Sea. This area is important ecologically and economically because it supports a commercial stock of Norway lobster (Nephrops norvegicus), and a nursery ground for European hake (Merluccius merluccius), as well as being subjected to high levels of fishing pressure. Here, Italian and Croatian bottom trawl fisheries mainly target Norway lobster while impacting juvenile hake. Single-species stock assessments for the target species indicate fluctuating trends between 2006 and 2013, as do the survey biomass trends of most of their prey, underlining the need for a multispecies management plan. The diet of the target species were examined and prey items partitioned into four groups. Consumption of prey groups by predators was modelled using a Holling Type II functional response. A modified biomass dynamic model was used to represent the prey dynamics, projecting them into the future for 10 years (2013-2022) and testing different management strategies, including a discard ban. The most effective management option was the protection of larger individuals, which led to a clear improvement in the stock abundance and spawning stock biomass of both hake and Norway lobster without significant adverse effects on their prey. The discard ban scenario appeared to have knock-on effects on both predators and some of their prey.
This study assesses the seabed pressure of towed fishing gears and models the physical impact (area and depth of seabed penetration) from trip-based information of vessel size, gear type, and catch. Traditionally fishing pressures are calculated top-down by making use of large-scale statistics such as logbook data. Here, we take a different approach starting from the gear itself (design and dimensions) to estimate the physical interactions with the seabed at the level of the individual fishing operation. We defined 14 distinct towed gear groups in European waters (eight otter trawl groups, three beam trawl groups, two demersal seine groups, and one dredge group), for which we established gear “footprints”. The footprint of a gear is defined as the relative contribution from individual larger gear components, such as trawl doors, sweeps, and groundgear, to the total area and severity of the gear's impact. An industry-based survey covering 13 countries provided the basis for estimating the relative impact-area contributions from individual gear components, whereas sediment penetration was estimated based on a literature review. For each gear group, a vessel size-gear size relationship was estimated to enable the prediction of gear footprint area and sediment penetration from vessel size. Application of these relationships with average vessel sizes and towing speeds provided hourly swept-area estimates by métier. Scottish seining has the largest overall gear footprint of ∼1.6 km2 h−1 of which 0.08 km2 has an impact at the subsurface level (sediment penetration ≥ 2 cm). Beam trawling for flatfish ranks low when comparing overall footprint size/hour but ranks substantially higher when comparing only impact at the subsurface level (0.19 km2h−1). These results have substantial implications for the definition, estimation, and monitoring of fishing pressure indicators, which are discussed in the context of an ecosystem approach to fisheries management.
We examined various fishing management options to recover exploited marine resources and ecosystems of the Northern-Central Adriatic Sea. Dynamic simulations were based on a spatial ecological model previously calibrated with time series of data. Scenarios regarding spatial management were evaluated with the establishment of two marine protected areas, respectively, in the Pomo pit and the northern region. In addition, three temporal simulations of temporary closures and overall reduction of fishing effort of demersal and pelagic fleets (bottom, mid-water trawls and purse seines) were also considered. Simulations were run for 45 years (1975–2020), including the calibration period (1975–2002), and changes in biomass and catch of marine resources were analyzed. Our results confirm that current fishing management in the Adriatic Sea does not have clear beneficial impacts for the recovery of exploited resources, which will remain depleted in 2020 if “business as usual” continues. Simulations of alternative management suggest that both protected areas could be beneficial for fish population recovery predicting an increase in the biomass of commercial fish and predatory organisms. Simulations of temporary closures and overall reduction of fishing effort also show significant benefits for several commercial resources. We argue that both management measures may be effective tools to recover exploited ecosystems of the Northern-Central Adriatic Sea and halt the decline of marine resources.
Effective management of fishing capacity requires reliable estimates of current capacity, and to this end most countries have developed a form of capacity measure usually based on some physical characteristics of the fleet. In the United Kingdom, the “capacity” measurement system currently in place is used as the basis of existing capacity reduction programmes. Each vessel has a number of Vessel Capacity Units (VCUs) defined by its size and engine power. An assumption is made that this measure is related to the ability of the fleet to catch fish. More recently, techniques have been developed to measure capacity directly in terms of potential output. In this paper, the fishing capacity of a sample of UK otter trawlers and a set of boats that primarily use static gear (i.e. nets and lines) is estimated using data envelopment analysis (DEA). Estimates are made on a species-by-species basis for the key species harvested. These are compared to the existing measures of physical capacity. The results suggest that VCUs may provide a reasonable approximation of fishing capacity for fleets using mobile gear, but may be inappropriate for fleets using static gear. Implications for capacity management based on the physical measures, given the results, are drawn.
U cilju proširenja znanstvene spoznaje o ekologiji i dinamici, a time i oblicima zaštite pridnenih naselja Jadranskog mora, prostorno zajedničko i ekonomski djeljivo obilježje oslića (Merluccius merluccius), trlje blatarice (Mullus barbtus) te skupine riba hrskavičnjača (Chondrichthyes) je studirano po prvi put uporabom GIS (Geographic Information System)tehnike. U tu svrhu, pregledno je objašnjena prostorna raspodjela slijedećih vrsta pridnenih riba: oslića, trlje blatarice te skupine hrskavičnjača. Analizom relativnog indeksa abundancije proučavanih vrsta riba, odnosno ulova na jediničnu lovnu površinu u području sjevernog i srednjeg Jadrana, nađeno je da navedene gospodarske vrste riba, u biološkom i gospodarskom pogledu, predstavljaju zajednička i djeljiva biološka dobra Jadranskog mora, čime je potkrepljena pretpostavka o potrebnoj uspostavi dogovorne politike između korisnika obnovljivih bogatstava Jadranskoga mora.
In recent years, fisheries management has succeeded in stabilizing and even improving the state of many global fisheries resources [1–5]. This is particularly evident in areas where stocks are exploited in compliance with scientific advice and strong institutional structures are in place [1, 5]. In Europe, the well-managed northeast (NE) Atlantic fish stocks have been recovering in response to decreasing fishing pressure over the past decade [3–6], albeit with a long way to go for a universal stock rebuild [3, 7]. Mean-while, little is known about the temporal development of the European Mediterranean stocks, whose management relies on input controls that are often poorly enforced. Here, we perform a meta-analysis of 42 European Medite-rranean stocks of nine species in 1990–2010, showing that exploitation rate has been steadily increasing, selec-tivity (proportional exploitation of juveniles) has been dete-riorating, and stocks have been shrinking. We implement species-specific simulation models to quantify changes in exploitation rate and selectivity that would maximize long-term yields and halt stock depletion. We show that stocks would be more resilient to fishing and produce higher long-term yields if harvested a few years after maturation because current selectivity is far from optimal, especially for demersal stocks. The European Common Fisheries Policy that has assisted in improving the state of NE Atlantic fish stocks in the past 10 years has failed to deliver similar results for Mediterranean stocks managed under the same policy. Limiting juvenile exploitation, advancing manage-ment plans, and strengthening compliance, control, and enforcement could promote fisheries sustainability in the Mediterranean.
Common sole in the northern and central Adriatic Sea: Spatial management scenarios to rebuild the stock, Journal of Sea Research (2014), doi: 10.1016/j.seares.2014.02.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Limited data, and the requirement to provide science-based advice for exploited populations, have led to the development of statistical methods that combine several sources of information into a single analysis. This approach, “integrated analysis”, was first formulated by Fournier and Archibald in 1982. Contemporary use of integrated analysis involves using all available data, in as raw a form as appropriate, in a single analysis. Analyses that were traditionally carried out independently are now conducted simultaneously through likelihood functions that include multiple data sources. For example, the traditional analysis of converting catch-at-length data into catch-at-age data for use in an age-structured population dynamics models can be avoided by including the basic data used in this conversion, length-frequency and conditional age-at-length data, in the likelihood function. This allows for consistency in assumptions and permits the uncertainty associated with both data sources to be propagated to final model outputs, such as catch limits under harvest control rules. The development of the AD Model Builder software has greatly facilitated the use of integrated analyses, and there are now several general stock assessment models (e.g., Stock Synthesis) that allow many data types and model assumptions to be analyzed simultaneously. In this paper, we define integrated analysis, describe its history and development, give several examples, and describe the advantages of and problems with integrated analysis.
Self-reporting of information is an inexpensive means for collecting data on fishing or other human activities, but the accuracy of self-reported data can be difficult to measure. Logbooks that record fishing activities are a common form of self-reporting that can provide vast amounts of information about a fishery. Using logbook data from trawlers from Oregon ports operating along the US Pacific coast during 1987–2001, this study examined (a) the consistency of reported tow locations and bottom depths and (b) the accuracy of reported retained catches of four groundfish species groups. Because logbook data during this period played no direct role in fishery management or stock assessments, there were no obvious incentives for trawl captains to deliberately report false logbook information. To evaluate consistency between tow locations and corresponding bottom depths, each tow was assigned to a 100-m bottom depth-band based on the reported tow location on a digital chart. The depth-bands based on the tow locations were then compared one-to-one with the depths reported in the logbooks and analysed to determine factors (e.g., year, quarter, vessel) contributing to the consistency between the reported locations and depths. Consistency was highest in the shallowest depth-bands and there was a strong interaction between depth and vessel. To evaluate the accuracy of the retained catches reported by the captains, the tow-by-tow logbook data were summed to the fishing-trip-level and compared to the official landing weights, recorded at the fish processing plants when the catches were off-loaded and weighed. The logbook weights relative to the corresponding official landing weights were analysed using zero-inflated generalized Poisson (ZIGP) regression models to determine factors (year, quarter, vessel) that were important explanatory variables. The analysis found strong year, quarter, and vessel effects for all three parts of the ZIGP: the mean value, the dispersion, and the proportion of zeros. The vessel effect was strongest. In a combined analysis, based on results from the other two analyses, vessels that were consistent in recording their depths and fishing locations had only a weak tendency to be accurate in recording their catches.
Primary determinants of the productivity of most fisheries are the level of fishing mortality and the age structure of the
catch. Constraints on nominal effort or catch and technical measures such as mesh sizes are typically the most effective methods
of ensuring productivity and sustainability. Stock assessment models are generally well adapted to assess the biological implications
(though less often the economic implications) of these measures. However, the increasing use of spatial management measures
such as marine protected areas (MPAs) or seasonal area closures presents new challenges for fishery managers. Assessment models
and data collection programs are rarely designed or adaptable for analysis of these measures. Using spatial management measures
effectively requires new models and data. Models of Georges Bank groundfish fisheries are presented and used to explore the
impacts of area closures in the context of the overall management system. Although the spatial dynamics of the models are
highly stylized, they illustrate mechanisms through which area closures can increase productivity and profitability of a spatially
heterogeneous multispecies fishery. The utility of taxes to control the distribution of effort is also explored.
This review focuses on the Norway lobster (Nephrops norvegicus) as a resource, describing how the fishery has developed from the 1960s to the present day to become one of the most economically important fisheries in Europe. In 2010, the total landings were 66,500tonnes, of which UK fishers landed a significant part (58.1%). The Nephrops fishery is also important for countries such as Ireland (11.7% of the total) and Sweden (1.9%) where it is of regional importance. Some are also taken in the Mediterranean, where Italian, Spanish and Greek fishers together take approximately 7% of the total landing. More than 95% of Nephrops are taken using single- or multi-rig trawlers targeting Nephrops or in mixed species fisheries. In regions such as Western Scotland and the Swedish West Coast, creel fisheries account for up to a quarter of the total landings. Across the range, a small proportion (<5%) is taken using traps in a fishery characterised by larger sized animals that gain a higher price and have lower discard and by-catches of ground fish with low mortalities. The trawling sector, however, is reducing the by-catches of ground fish with the aid of technical measures, such as square-mesh panels and grids and national systems of incentives. Assessments for Nephrops are operated via the 34 functional units (FUs) regarded as stocks. Changes in management procedures have arisen as a result of the advisory input from underwater TV fishery-independent stock surveys. The total allowable catch does not follow FUs but is agreed upon per management area.
The identification of groups of vessels with the same exploitation pattern (e.g. gear used, fishing ground, target species) over time, usually referred to as a "metier", is a major topic of fishery management. However, m tier detection on fishing trips is still done using the incomplete or biased information present in declaration of landings (logbooks), under the assumption that the reported landings profiles reflect intended catches. Nowadays, fishing effort can be tracked at high spatial resolution using vessel monitoring systems (VMS). VMS potentially provides information about vessels fishing activity if the frequency of signals is natively high or appropriately interpolated. An artificial neural network is used to analyse interpolated VMS tracks and Vessel Register data to identify fishing activity. A multilayer perceptron network (MPN) was trained to recognize one among 15 possible m tiers from a series of 33 variables: 12 in binary form for licensed gears, 6 probability classes for vessel speed. 3 for vessel heading and 7 for sea depth, respectively. The MPN was iteratively trained on subsamples of a large dataset corresponding to the activity of the Italian fishing fleet, for which information about m tier was collected and validated by on-board observations by scientific operators, and then tested on other subsets of the data. The best architecture for MPN was identified and analysed. The mean percentage of correct predictions obtained on the test datasets was very high (>94%), confirming that VMS data can provide information on vessel activity. Overall, these findings suggest that this is a promising approach to assign fishing effort, resolved at single trip scale, to specific metiers, even giving independent assessment of fishing activity with respect to those provided by logbook and capture data.
The Vessel Monitoring by satellite System (VMS) is a powerful tool in fishery management, since it allows for high resolution analyses of fishing activity and quantitative evaluations of fishing effort at both spatial and temporal scale. Given that the main VMS limit is represented by the temporal resolution (generally 2 h) of signals, a series of approach has been developed to interpolate vessels positions. The newest and most powerful method in this framework is based on cubic Hermite splines (cHs), which have been efficiently tested against the conventional straight line interpolation over a dataset representing fishing activity by beam trawl. However, this method has never been applied on other different gears and/or métiers. Here we propose a new approach (CRm), which is a modification of the Catmull–Rom algorithm (CR). This new method takes into account for the different aspects involved in vessel navigation, such as the combined actions of human control and drift by sea current and wind (if present). The drift component is not observed, but is estimated within the method, using the VMS data. This method has been developed in order to model the behaviour of vessels that operate using different gear types. The CRm method was compared to the cHs method, using three reference datasets (each containing VMS signals at intervals of 20 min) corresponding to three different métiers largely used in Mediterranean fisheries: bottom otter trawl for demersal species (OTB), trammel nets for demersal species (GTR), and purse seine for small pelagic fish (PS), which differ each other for the dynamic aspects connected to the use of fishing gears, and represent an archetype of the three groups actually used to classify fishing gears (namely towed, active and passive). The comparison was carried out both analyzing the error affecting interpolation of single tracks and converting the interpolated tracks into gridded data to be used for computation of ecological indicators of fishing pressure. All the results coherently evidences that the CRm algorithm performs better in interpolating trawl tracks (OTB) and that, moreover, it is able to capture the complex behaviour characterizing the trajectories of vessels performing the other two inspected métiers (GTR and PS). Finally, CRm allows a better estimation of fishing effort, as measured by ecological indicators. These findings support the idea that the conceptual formulation of CRm method is appropriate to model whatever fishing tracks presently generated by fishery vessels and could be efficiently applied in order to obtain better estimation of fishing pressure and, if sensitivity data are available, of fishing impacts.
The Faroe Islands, located in the northeastern Atlantic Ocean, utilize a spatial-and effort-based system of fisheries manage-ment, explicitly incorporating ecosystem considerations in their policies. This management system was introduced relatively recently (mid-1990s). Given the importance of fishing to the Faroe economy and culture, considerable interest has been ex-pressed in the evaluation of these new management measures at the ecosystem level. We used Ecopath with Ecosim to examine alternative management options for the Faroe Islands fisheries and compared these options with the status quo. Spatially explicit simulations were carried out using the Ecospace routine. Simulations suggest that current area closures could be considered beneficial in conserving major stocks of demersal species, with biomass for cod (Gadus morhua), haddock (Melanogrammus aeglefinus) and other demersal species increasing over the 10-year simulation period. Simulated removal of the closure sys-tem reduced the effect of the projected stock increases considerably. Greenland halibut (Reinhardtius hippoglossoides), one of the major deep-water species, and blue whiting (Micromesistius poutassou), one of the main pelagic species, did not benefit from the existing spatial management. Simulated additional offshore closures of at least 20% of habitats deeper than 200 m benefited Greenland halibut only. Both, Greenland halibut and blue whiting stocks benefited from drastic reductions in fish-ing effort (between 20 and 50% reductions from 1997 effort levels). Considerable uncertainty underlies the basic input data, which might have major consequences for the dynamic behaviour of the simulations, and thus might significantly alter the outcomes.
The spatial structure of several exploited species within and among known populations of the Northwest Atlantic is reviewed using past and current knowledge. For each species, the coherence of existing management units with the spatial scale of population dynamics (populations, sub-populations, and spawning components) is summarized. The implications of this match or mismatch of spatial scales in the maintenance of biodiversity within and among populations are also discussed.
The common approaches to evaluation and management of marine finfish stocks assume discrete populations. While it has long been recognized that this assumption is complicated to some degree by migrations and mixing between management units, there has been little attention paid recently to the complexity of spawning components within management units. Several marine finfish species appear to have more complex stock structure than is recognized, and in many cases, management units contain stock complexes or metapopulations with several spawning components rather than single discrete populations. Unfortunately, these spawning components are typically difficult to define from traditional fisheries data, or to discriminate by conventional stock identification techniques. Failure to recognize or to account for this complex stock structure in management, however, may lead to erosion of spawning components, with unknown ecological consequences. The management of complex fish stocks, at appropriate scales, so as to preserve stock complexity, therefore, remains a major challenge. Maintenance of the full diversity of spawning locations and times is an important aspect of topical discussions of biodiversity and marine protected areas. Consequently, the importance of stock identification will increase as a result of a new emphasis on management which takes into account stock complexity within areas traditionally assumed to contain a single stock. This new emphasis on stock complexity is necessary if management is to comply with a “precautionary approach” to fisheries management.
This work presents a stock-effort dynamical model of a fishery subdivided on several fishing zones. The stock corresponds to a fish population moving between different zones, on which they are harvested by fishing fleets. The bio-economical model is a set of ODE’s governing the fishing efforts and the stocks on the different fishing zones. We take profit from the existence of two time scales (a fast one for fish migration and fleets movements, and a slow one for fish growth and mortality and fleets revenue) to construct a reduced (aggregated) model. The aggregated model describes the global evolution of the harvested stock as well as the total fishing effort. The mathematical analysis of the model allows the optimization of the spatial distribution of the fishing effort and the identification of an efficient set of management measures, which corresponds in one hand to set an appropriate system of tax and/or subsidies, and on the other hand to control the displacement of the fleets between the fishing zones, in order to increase the total activity.
In order to provide reliable scientific advice and support for fisheries management, it is necessary to evaluate the biological and economic sustainability of complex fisheries, such as multi-species multi-fleet fisheries. Existing policy-screening modelling tools are not fully suitable in this purpose due to either an over-simplified description of population dynamics, or due to the lack of consideration of economic aspects. In this paper, we present a package that enables quantitative bioeconomic assessment of management scenarios. Population dynamics is described through spatially- and seasonally-explicit models. Exploitation dynamics is characterized by several fishing activities with specific spatial and seasonal features, and practiced by several kinds of vessels with specific technical characteristics. Exploitation costs and revenues are considered at several levels: the fishing trip, the fishing unit (vessel and crew), and the vessel owner. The model is generic and can be used for different types of fisheries. A database is attached to the software for the storage and updating of information for each fishery. This includes the specification of model dimensions and of the parameters describing populations and exploitation. Several model assumptions regarding either population or exploitation may be adapted to suit a specific fishery. Both policies and corresponding fishers' response may be interactively specified through JAVA (TM) scripts. This version of ISIS-Fish allows for the calculation of biological and economic consequences of a range of policies, including conventional ones like catch and effort controls, and alternative policies such as marine protected areas. To facilitate policy-screening in a high-dimension parameter space, the software includes features, like interfaces for sensitivity analysis and simulation queues. (C) 2009 Elsevier B.V. All rights reserved.
Nephrops norvegicus: stock variability and assessment in relation to fishing pressure and environmental factors
- Anon
Anon, 1994. Nephrops norvegicus: stock variability and assessment in relation to fishing
pressure and environmental factors. Eur. Comm. Final Report DG, XIV, Med. 91/003
209, 84.
The State of Italian Marine Fisheries and Aquaculture
- S Cataudella
- M Spagnolo
Cataudella, S., Spagnolo, M., 2011. The State of Italian Marine Fisheries and Aquaculture.
Rome (Italy), URL: https://www.politicheagricole.it/flex/cm/pages/ServeBLOB.
php/L/IT/IDPagina/6412/ >.
Council Regulation (EC) No. 199/2008 concerning the establishment of a Community framework for the collection, management and use of data in the fisheries sector and support for scientific advice regarding the common fisheries policy
EC, 2008. Council Regulation (EC) No. 199/2008 concerning the establishment of a
Community framework for the collection, management and use of data in the fisheries sector and support for scientific advice regarding the common fisheries policy.
Off. J. Eur. Union L60, 1-12.
laying down detailed rules for the implementation of Council Regulation (EC) No 1224/2009 establishing a community control system for ensuring compliance with the rules of the common Fis
EC, 2011. Commission Implementing Regulation (EU) No. 404/2011 of 8 April 2011
laying down detailed rules for the implementation of Council Regulation (EC) No
1224/2009 establishing a community control system for ensuring compliance with
the rules of the common Fis. Off. J. Eur. Union L112 1-30/04/2011.
Diurnal changes in fishery resources catchability by bottom trawl in the Adriatic Sea
- C Froglia
- M E Gramitto
Froglia, C., Gramitto, M.E., 1986. Diurnal changes in fishery resources catchability by
bottom trawl in the Adriatic Sea. FAO Fish. Rep. 345, 111-118.
An Estimate of Growth and Mortality Parametersfor Norway Lobster (Nephrops Norvegicus) in the Central Adriatic Sea
- C Froglia
- M E Gramitto
Froglia, C., Gramitto, M.E., 1988. An Estimate of Growth and Mortality Parametersfor
Norway Lobster (Nephrops Norvegicus) in the Central Adriatic Sea, Report of the 5th
National Data for Fisheries Sector
IREPA, 2012. National Data for Fisheries Sector [WWW Document]. URL http://www.
irepa.org/it/dati-sistan/dati-nazionali/2012.html/ >.
Nephrops norvegicus (L.) otvorenog jadrana
- J Karlovac
Karlovac, J., 1953. Nephrops norvegicus (L.) otvorenog jadrana. Zb. I Kongr. biol. Jugosl.
213-219.
Recherches sur l'ichthyobentos dans les profondeurs de l'Adriatique méridionale et possibilité d'exploitation au moyen des palangres
- J Kirinčić
- V Lepetić
Kirinčić, J., Lepetić, V., 1955. Recherches sur l'ichthyobentos dans les profondeurs de
l'Adriatique méridionale et possibilité d'exploitation au moyen des palangres. Acta
Adriat. 7, 1-113.
Nnls: The Lawson-Hanson Algorithm for Non-negative Least Squares (NNLS)
- K Mullen
- I Van Stokkum
Mullen, K., van Stokkum, I., 2015. Nnls: The Lawson-Hanson Algorithm for Non-negative
Least Squares (NNLS). URL: https://cran.r-project.org/web/packages/nnls/nnls.
pdf/ >.
Parliament European, 2008. Fisheries in Italy [WWW Document]. URL http://www.
europarl.europa.eu/RegData/etudes/note/join/2008/397238/IPOL-PECH_NT(2008)
397238_EN.pdf/ >.
Programma nazionale per la raccolta dei dati alieutici -Campionamento biologico delle catture della pesca professionale di demersali e piccoli pelagici in alto e medio Adriatico (GSA 17), anno 2014. Progetto del Ministero Italiano delle Politiche Agricol
- A Santojanni
- S Angelini
- A Belardinelli
- P Carpi
- S Colella
- C Croci
- F Domenichetti
- F Donato
- M Martinelli
- M Panfili
- C Tesauro
Santojanni, A., Angelini, S., Belardinelli, A., Carpi, P., Colella, S., Croci, C., Domenichetti,
F., Donato, F., Martinelli, M., Panfili, M., Tesauro, C., 2015. Programma nazionale per
la raccolta dei dati alieutici -Campionamento biologico delle catture della pesca
professionale di demersali e piccoli pelagici in alto e medio Adriatico (GSA 17), anno
2014. Progetto del Ministero Italiano delle Politiche Agricol. 229 URL: http://
www.cnr.it/istituti/ProdottoDellaRicerca.html?cds=080&id=308328.