Ana Gordoa

Spanish National Research Council | CSIC · Center for Advanced Studies of Blanes

We present the Terms of Reference for a case study on a Mediterranean eco-region focusing on the environmental component of the Ecosystem Report Card. The objective of this case study is to describe and monitor the variability of environmental processes in the Mediterranean Sea that affect the ecology of large pelagic fishes, with a particular atte...

Recreational spearfishing is a fishing method that occurs globally, yet receives considerably less attention in the scientific literature relative to other recreational fishing methods, such as angling. Lack of scientific information on spearfishing may negatively affect the development and management of marine recreational fisheries. We conducted...

This study analyses the costs of marine recreational activity in Spain for the main fishing modalities and provides a cost-effective economic indicator (CEI) for each of them. The activity costs of 4,999 fishers were collected through an online survey, along with other fishing information. The published results of this survey, catch rates and catch...

The spatial distribution patterns of Merluccius capensis in the Namibian waters were investigated and related to average environmental conditions during 1996-2020. Fisheries-independent data and simultaneously collected water temperature and dissolved oxygen data were used from austral summer surveys. A geostatistical kriging approach was employed...

Spearfishing is practiced by a small fraction of younger recreational fishers and has received considerably less scientific attention than angling. This knowledge gap may negatively affect the ability for developing sustainable marine recreational fisheries. We address this through a global systematic review of the literature pertaining to marine s...

This work is the result of an international research effort to determine the main impacts of the COVID-19 pandemic on marine recreational fishing. Changes were assessed on (1) access to fishing, derived from lockdowns and other mobility restrictions; (2) ecosystems, because of alterations in fishing intensity and human presence; (3) the blue econom...

This study analyses growth rates of bluefin tuna young-of-the-year in the Mediterranean. Potential differences in growth rates were examined between years (2013 and 2016) and regions (eastern, central and western Mediterranean). A total of 134 specimens were aged by analysing otolith microstructure. Fish sizes ranged between 14.7 and 57 cm fork len...

Since 2014, the global land and sea surface temperature has scaled 0.23 °C above the decadal average (2009–2018). Reports indicate that Mediterranean Sea temperatures have been rising at faster rates than in the global ocean. Oceanographic time series of physical and biogeochemical data collected from an onboard and a multisensor mooring array in t...

A B S T R A C T This study attempts to improve the scientific knowledge of charter fishing on the Aegean coast of Turkey, where fishing activity and ecological indicators were investigated. Fishing and socio-economic data from both charter boat owners and charter fishers were collected using on-site questionnaires, and seasonal on-board surveys dur...

The European Parliament is concerned about the lack of information on the relevance of nine million Europeans engaged in marine recreational fishing (MRF), committing Member States to encourage environmental and socioeconomic sustainability of the sector. The objective of this paper is to provide recommendations to guide research actions and manage...

Pelagia noctiluca is the most successful and well-studied jellyfish in the Mediterranean Sea. They tolerate a wide range of water temperatures and succeed in low to medium food regimes, but factors driving its distribution and population dynamics remain poorly understood. Here we applied a multiscale analytical approach using survey data and from a...

This apendix contains: Species compositions by modality in each Autonomous Community, and species-selective fishers' catch compositions by region and modality

This study represents the first nationwide assessment of marine recreational fishing catch compositions in Spain. Catch data from 7848 recreational fishers were collected using an online survey that was conducted from February 2016 to February 2017. The major modalities of the recreational fishing sector: shore fishing, boat fishing, and spearfishi...

En Europa practican la pesca marítima recreativa (PMR) nueve millones de aficionados que generan un gasto de 6 000 millones de euros anuales. En España se estima que hay 300 000 pescadores recreativos que realizan un gasto de 217 millones de euros anuales para desarrollar su actividad. Por estos motivos, la Política Pesquera Común (PPC) reconoce qu...

Resumen: En Europa practican la pesca marítima recreativa (PMR) 10 millones de aficionados que generan un gasto de 6 000 millones de euros anuales [1]. En España se estima que hay 300 000 pescadores recreativos que realizan un gasto de 217 millones de euros anuales [1]. Por estos motivos, la Política Pesquera Común (PPC) reconoce que "la pesca recr...

Characterizing fish communities must be a priority to safeguard resources and determine critical changes. Here, species richness and the spatial and temporal evolution in the structure of fish assemblages were analysed based on photos taken in underwater free-diving contests. A total of 29 contests held from 2008 to 2015 at four different locations...

Marine recreational fishing (MRF) is a high-participation activity with large economic value and social benefits globally, and it impacts on some fish stocks. Although reporting MRF catches is a European Union legislative requirement, estimates are only available for some countries. Here, data on numbers of fishers, participation rates, days fished...

Increasing the knowledge about littoral fish communities is important for ecological sciences, fisheries and the sustainability of human communities. The scarcity of baseline data at large spatial scales in a fast-changing world makes it necessary to implement special programs to monitor natural ecosystems. In the present study, we evaluate littora...

Intentional mislabelling of seafood is a widespread problem, particularly with high-value species like tuna. In this study we examine tuna mislabelling, deliberate species substitution, types of substitution and its impact on prices. The survey covered the commercial chain, from Merca-Barna to fishmongers and restaurants in the Spanish Autonomous C...

Primary data: codes of sampled areas. (PDF)

Primary data: restaurants. (PDF)

Tuna species name (commercial designations) accepted in Spain and in littoral Autonomous Communities. (DOCX)

Primary data: point of sales. (PDF)

FASTA sequences. (XLSX)

An important use of the length-weight (L-W) equation for Atlantic bluefin tuna, Thunnus thynnus, is to convert the straight fork length (SFL) measured with stereocameras during the caging of BFT to catch weight (RWT). The literature and other available data indicated that using the most recent ICCAT L-W relationships overestimate the RWT attributed...

This document presents the main conclusions obtained in the 1st Workshop on Recreational Fishing on the Iberian Atlantic Coast, held on 11 and 12 November, 2016 in Vigo (Spain), within the framework of the RECREGES Project, "Research initiatives on recreational fisheries in Europe. Integration in the fisheries management models of the Galicia-North...

Coastal, small-scale fisheries (SSF), whether artisanal (professional) or recreational, represent important socioeconomic activities across Europe that are currently undergoing a number of changes. This paper reviews and analyses the drivers of these changes, and makes recommendations for the future management of SSF. From the biological standpoint...

The Spearfishing Association of Barcelona (APS) recently celebrated its 70 th anniversary and decided to write a manifesto called: " The Barcelona Agreement: A Manifesto Towards the Spearfishing of the Future ". The Manifesto was discussed and approved during a round table at the Maritime Museum of Barcelona on 27 February 2016, in which delegates...

This study presents the first results on Atlantic bluefin tuna (Thunnus thynnus) individual spawning duration and its short-term temporal behavior. The study was based on direct measurements resulting from mtDNA analysis of the offspring of spawners held in transport cages during the 2013 spawning monitoring survey in Balearic waters. The number of...

Fish farms have been shown to aggregate large numbers of wild fish in their surroundings. Although little is known about how this affects the local fishery, two hypotheses have been put forward; a trapping and a protecting effect on wild fish. This study provides the first monitoring of commercial and recreational fishing activity at a fish farm. W...

This study analysed the temporal pattern of Atlantic bluefin tuna (ABFT) spawning in the Balearic spawning ground and examined its reproductive performance after years in captivity. Furthermore, ABFT hatching time at different on-site temperatures was determined for the first time. Spawning surveys were carried out in 4 spawning seasons (2009-2012)...

The factors modulating recruitment success of Cape hake Merluccius capensis in Namibian waters are still unresolved. In this study, we used generalised additive models, regression tree analysis and the conventional Ricker model to examine the effect of environmental indices and spawning stock biomass (SSB) on hake recruitment success for the period...

Most of the Atlantic bluefin tuna caught by the purse-seine fleet in the Mediterranean Sea are transferred alive into transport cages and towed to coastal facilities where they are fattened. This major fishery is targeting aggregations of reproductive bluefin tuna that continue spawning within the transport cages. Our study is the first attempt to...

This study investigates the predation of P. noctiluca ephyrae on Atlantic Bluefin tuna (ABFT) eggs under different experimental conditions. The specific factors considered in the experimental design were: a) water mix conditions to explore predation under two-dimensional (2D) and three-dimensional (3D) prey distributions, b) prey density to investi...

Factors influencing within-farm variability of wild fish aggregations have not been systematically studied. We tested the hypothesis that fish abundance and species composition vary between feeding and non-feeding periods and different bottom substrates within a Sparus aurata (L.) farm. Sampling took place during feeding and non-feeding periods on...

Most of the Atlantic bluefin tuna caught by the purse-seine fleet in the Mediterranean Sea are transferred alive into transport cages and towed to coastal facilities where they are fattened. This major fishery is targeting aggregations of reproductive bluefin tuna that continue spawning within the transport cages. Our study is the first attempt to...

Ecomorphological changes as a result of natural perturbations in estuarine fish communities were investigated in two South African estuaries (Swartvlei and East Kleinemonde), both before and after the loss of aquatic macrophyte beds in these systems. The fish communities were analysed using an ecomorphological diversity index (EMI) and the results...

Fish farms cause wild fish to aggregate nearby and thus act to modify their distribution, but the spatial and temporal extent of the attraction effect around farms is still poorly understood. We examined attraction using an integrated approach combining 3 factors: spatial extent, depth and season. We analysed an Atlantic bluefin tuna Thunnus thynnu...

The Atlantic bluefin tuna (Thunnus thynnus) is an extraordinary fish that has amazed humanity since ancient times. However, the continuous overexploitation of this fishery, particularly in the Mediterranean Sea, could result in a total collapse of this resource. Currently, this species is managed as two stocks: Western Atlantic and Mediterranean-Ea...

The density of the 40 most abundant demersal fish species off Namibia is inversely scaled to their average length, similar to the scaling of mortality to fish length. However, the density of individual fish species is, on average, scaled to the −2 power of average fish length in the aggregates, indicating that biomass increases (slope > −3) during...

The economic and harvest impact of Marine Recreational Fishing (MRF) in the Çanakkale Strait were analysed along with fishing policy, sociology and habits of fishers. Data sources included field survey data carried out along the entire length of the anakkale Strait and policy information gathered from published sources. MRF policy is commendable, e...

Demersal fish communities off southern Namibia were analysed on the basis of seven winter and five summer stratified random sampling cruises between 1983 and 1990. The 37 most abundant species selected for analysis represented 78-&ndash96 per cent of the total estimated biomass. The biomass of most of them decreased over the period of study. Howeve...

A good relationship between the variability in measurements of Cape hake Merluccius capensis biomass during winter and summer swept-area research surveys and sea surface temperature off southern Namibia for the years 1983–1990 is presented. The results call into question the hypothesis that hake density is related to biomass and imply that abnormal...

Gordoa, A., Olivar, M. P., Arevalo, R., Viñas, J., Molí, B., and Illas, X. 2009. Determination of Atlantic bluefin tuna (Thunnus thynnus) spawning time within a transport cage in the western Mediterranean. – ICES Journal of Marine Science, 66: 2205–2210. For the first time, tuna spawning in a transport cage being towed from the western Mediterranea...

Spatial and temporal variations in the structure of fish assemblages were analysed based on the catch data from a total of 2329 shore-based sport fishing tournaments held in north-eastern Spain from 2002 to 2006 with a view to characterizing the infralittoral system along 400 km of coastline and assessing the usefulness of these data as an addition...

We address the major surface signatures of chlorophyll a in the Catalan Sea within the context of the dynamics of the north-western Mediterranean basin. Monthly composites from MERIS measurements and CHL products for Case 1 waters were analysed from June 2002 to June 2005. Composite images of variability were used to identify surface dynamics. The...

IntroductionComparisons between the Mediterranean and AustraliaConclusion NoteReference

To identify spatio-temporal distribution in Namibian Cape hake (M. paradoxus and M. capensis), incidental hake catch by the horse mackerel fleet and targeted catch by the hake fleet were analysed for the period 1999–2004. The targeted catch, 45 955 fishing days, came from hake fishery logbooks and the incidental catch, 24 689 trawls, from observers...

In order to determine the factors governing the spatial distribution of effort, it is essential to better understand the relationship between CPUE and abundance. In this study the spatial distribution of effort of the Namibian hake trawl fleet is examined by looking at competitive abilities among vessels, spatial allocation of effort, competition b...

In order to determine the factors governing the spatial distribution of effort, it is essential to better understand he relationship between CPUE and abundance. In this study the spatial distribution of effort of the Namibian hake trawl fleet is examined by looking at competitive abilities among vessels, spatial allocation of effort, competition be...

By counting otolith daily increments juvenile Cape hake Merluccius capensis were found to grow faster than European hake Merluccius merluccius. The mean frequency of translucent zones in juveniles 130–240 mm LT were higher (×3·2) than the annual frequency, although their mean duration was shorter (1 month) than a season. Comparison between micro- a...

Conditions for primary production have been studied in Namibian waters during the period: October 1997-December 2003. The variables used have been: Sea Surface Temperature (SST) from the Advanced Very High Resolution Radiometer (AVHRR) and chlorophyll concentration from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) imagery. Temporal, latitudinal...

The monthly and spatial patterns of chlorophyll concentration have been analysed for the northern Benguela upwelling system, which is characterised by its strong seasonality. Sea-viewing Wide Field-of-view Sensor data have been used to determine temporal patterns and to identify optimal conditions for chlorophyll production from October 1997 to Oct...

The biomass size spectra in the littoral rocky fish communities in the Medes Island Marine Reserve and three unprotected localities from the NW Mediterranean were studied over a period of two years. A large number of individuals (81 478 in the protected area and 59 536 in the unprotected zones), belonging to 57 species, were censused. Communities w...

This paper describes the use of multinomial logistic regression analysis to calculate the probability of strong, average or weak recruitment of Cape hake (Merluccius capensis). The model includes environmental indices, describing the extent of warm-water intrusion as well as the upwelling strength for different areas and periods over 2 years—from s...

Remote sensing is an important facet of fishery research and fishing operations because oceanographie conditions strongly influence natural fluctuations of fish stocks. Accordingly, satellite capabilities in fisheries have been long emphasized. Applications of satellite remote-sensing capabilities for fisheries from 1987 to 1998 are reviewed, empha...

 Visual censuses conducted in a marine reserve (Medas Islands) were used to estimate the natural mortality rates (M) for five common fish species in the NW Mediterranean Sea (Coris julis, Diplodus annularis, D. sargus, Serranus cabrilla and Symphodus roissali). Visual censuses of these same five species were also performed at three sites in unprote...

The monthly and spatial patterns of the Namibian hake fishery are analysed for the period 1994–1997. A strong, but misleading negative relationship between monthly catch rates (CPUE) and fishing effort was observed, while no spatial correlation between these two variables were found, which suggests, for this fishery, that monthly CPUE as an index o...

Age and growth patterns of four common species of wrasses, Labrus merula, Coris julis, Symphodus roissali and Symphodus tinca, from the north-western Mediterranean sea are analysed. Length-at-age values are estimated from otoliths from which the first annual hyaline ring is determined by reading daily rings. The growth patterns are well described b...

Age and growth patterns of adults of three common species of sparids, Diplodus vulgaris, D. sargus and D. annularis from the north-western Mediterranean Sea are analyzed. Length-at-age values are estimated from otoliths and growth patterns are well described by the von Bertalanffy growth equation. The sampled length interval ranged from 8–40, 28 an...

Biomass spectra in the different benthic fish assemblages at depths between 100 and 800 m off the coast of Namibia were studied over a period of 3 yr. These assemblages were located in areas spanning active upwelling centres on the shelf and zones of lower productivity on the lower slope. The slopes of the curves for the normalized size distributio...

The preference of large (>60 cm total length) Cape hake (Merluccius capensis Castelnau, 1861) for small conspecifics under natural conditions was analyzed off southern Namibia (S.E. Atlantic) between 1983 and 1989. The results indicate that cannibalism is not related to the density of the small conspecifics nor to the density of alternative prey, b...

The Benguela current system is located off the South-east Atlantic coast of Africa between 17°S and 35°S. This is one of the four major eastern boundary current regions in the world’s oceans. Coastal upwelling is the most important feature in such systems, in which high primary productivity supports large commercial fisheries (Cushing, 1971). Many...

We used Monte Carlo simulations to examine the reliability of assessments following a method of separable catch-at-age analysis (Methot's stock synthesis approach). Our simulations were based on the widow rockfish (Sebastes entomelas) fishery off the west coast of the continental United States. We designed the study to examine how the performance o...

The diurnal pattern in the catch rate and feeding activity of Namibian hakes (Merluccius capensis and Merluccius paradoxus) was studied. Merluccius paradoxus fed more actively during the night, whereas the opposite was the case for M. capensis. However, catch rates for both species followed the same diurnal pattern. At night, the availability of th...

Data on hake (Merluccius capensis and Merluccius paradoxus) abundance along the Namibian coast showed both species to have strongly aggregated spatial distributions. In addition, average fish size increased with depth, suggesting that the formation of hake aggregation is based on size-dependent shoaling behaviour. Hake spacing was size dependent wi...

Management of the Cape hake (Merluccius capensis) stock off the coasts of Angola and Namibia has been based on surplus production modeling, which incorporates an assumption of constant catchability. Results of least-squares catch-at-age analysis and virtual population analysis were used to estimate catchability from 1968 to 1986. Estimated catchabi...

The effect of bottom-water dissolved oxygen on the structure of demersal fish communities off south Namibia was analized. Collections were made during two cruises of the zone in winter 1987 and summer 1988, i.e., before and after the intensive upwelling season. Multivariate analysis revealed four distinct associations, separated by latitude (ca 27S...

We investigated prey selection by the monkfish, Lophius upsicephalus. This sit-and-wait predator preferentially selected prey types that would be expected to react to the lure of the illicium. Prey size selection was dependent on predator size, with larger predators feeding on a wider range of prey sizes.