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Estimating post-release mortality of European sea bass based on experimental angling
Abstract
European sea bass (Dicentrarchus labrax) is an important target species for recreational and commercial fisheries. In recent years, the spawning stock biomass has declined markedly in some areas, and strict management measures have been introduced. However, the development of appropriate stock assessment and fisheries management has been hampered by a lack of information on post-release mortality. This study
investigated post-release mortality of sea bass captured with common recreational fishing gear under experimental conditions in an aquaculture facility over 10 d. Three experiments investigated: (i) the effects of different bait types; (ii) the impact of prolonged air exposure; and (iii) the impact of deep hooking on post-release mortality. By combining the experimental results with country-specific information on sea
bass angling practices, estimates of post-release mortality are provided for the northern sea bass stock. No mortality was observed for sea bass captured on artificial baits. The use of natural baits resulted in a mortality of 13.9% (95% CI 4.7–29.5%), which was associated with deep hooking, hooking injuries, and prolonged air exposure. The use of artificial baits and short air exposure (max 30 s) increased survival probability, whereas deep hooking resulted in 76.5% (95% CI 50.0–93.2%) mortality. Depending on country-specific angling practices, post-release mortality estimates ranged from 2.8% to 9.1% (mean 5.0%, 95% CI 1.7–14.4%) for northern sea bass. Despite these relatively low mortality estimates, post-release mortality should be considered in stock assessments as its cumulative impact may be high. Moreover, post-release mortality can be reduced by implementing species-specific best practice guidelines.
... Using Ruiz et al. (2016) data, Molenaar and Steenbergen (2016; also unpublished) investigated hooking locations and the occurrence of barotrauma during two observer trips on a Dutch commercial hook and line fishing vessel and estimated a discard survival rate of 93%. The most comprehensive study documented the effects of air exposure, deep hooking (hooking inside the oesophagus or stomach), and different baits/lures on post-release mortality of reared sea bass during a ten-day holding period in an aquaculture facility (Lewin et al., 2018). Deep hooking was a significant driver of postrelease mortality, causing the death of 76.5% (95% CI=50-93.2%) of sea bass. ...
... The use of natural bait caused a higher mortality rate (13.9%, 95% CI=4.7-29.5%) compared to artificial lures (0% mortality, 95% CI=0-11.9%, and 95% CI=0-10.9% for shad and wobbler lures, respectively; Lewin et al., 2018). Prolonged air exposure (over five minutes) caused 10% post-release mortality (95% CI=0.3-44.5%), ...
... whilst shorter exposure resulted in no associated mortality (0%, 95% CI=0-16.8%). Lewin et al. (2018) used these data together with country-specific information on recreational sea bass fishing practices to generate country-specific and stock level recreational post-release mortality estimates for the northern sea bass stock. ...
Sea bass is a high risk of being a choke species in any potential Landing Obligation approach being applied in future but exemptions are currently not possible because limited studies of discard survival exist. In addition, under the current approach of applying vessel catch limits, fisheries managers need to know the full mortality impact of discarding in different metiers, to inform decisions on establishing more flexible limits aimed at reducing discarding of unavoidable catches, particularly in demersal trawls. This information will be used to inform fisheries managers about potential exemptions from an EU Landing Obligation being applied in future, and suitable UK management approaches for sea bass on leaving the EU.
The overall aim of this proposal is to consider the potential for sea bass to survive after being discarded from commercial fisheries.
This project estimates sea bass discard survival rates across the length range of the catch using tagging for static gillnets, drift nets, and otter trawls, and desk-based approaches for hook and line fisheries.
... In an ICES report, Ruiz et al. compared post-release mortality rates of wild sea bass caught by recreational anglers with different methods (natural bait, artificial lures and hook types) and held in net pens after being released in the harbour of Bilbao, Northern Spain (ICES,2018). Lewin et al. (2018) documented the effects of air exposure, deep hooking (hooking inside the oesophagus or stomach) and different lures on post-release mortality of reared sea bass during a ten-day holding period in an aquaculture facility (Lewin et al., 2018). Deep hooking was a significant driver of post-release mortality, causing the death of 76.5% (95% CI = 50%-93.2%) of deep-hooked sea bass. ...
... In an ICES report, Ruiz et al. compared post-release mortality rates of wild sea bass caught by recreational anglers with different methods (natural bait, artificial lures and hook types) and held in net pens after being released in the harbour of Bilbao, Northern Spain (ICES,2018). Lewin et al. (2018) documented the effects of air exposure, deep hooking (hooking inside the oesophagus or stomach) and different lures on post-release mortality of reared sea bass during a ten-day holding period in an aquaculture facility (Lewin et al., 2018). Deep hooking was a significant driver of post-release mortality, causing the death of 76.5% (95% CI = 50%-93.2%) of deep-hooked sea bass. ...
... and 95% CI = 0%-10.9% for shad and wobbler lures, respectively; Lewin et al., 2018). Prolonged air exposure (five minutes) caused 10% post-release mortality (95% CI = 0.3%-44.5%), ...
Despite the implementation of technical management measures to facilitate stock recovery of European sea bass, Dicentrarchus labrax (L.), the survival rate of discarded hook-and-line caught sea bass remains unknown. This makes the effectiveness of management measures that result in discarding difficult to assess. Therefore, a questionnaire was distributed to 421 UK-based commercial hook-and-line fishers (65 respondents) to characterise how sea bass are caught, handled and released. Responses suggested fishing was selective with a reported estimated mean discard rate of 12.9% (±3.3% SE). Low rates of foul and deep hooking, and short periods of air exposure were reported. Combined with data from a post-release mortality experiment using hook-and-line caught captive sea bass, a fleet-wide discard survival rate of 89.3% (±2.6% SE) was calculated for the UK commercial hook-and-line sea bass fishery. This survival rate suggests that technical management measures, for example minimum conservation reference sizes and catch limits, could be effective tools for managing the sea bass hook-and-line fishery.
... According to literature reviews (Muoneke and Childress, 1994;Bartholomew and Bohnsack, 2005;Hühn and Arlinghaus, 2011), the anatomical hooking location and related hooking injuries/bleedings are important factors affecting post-release mortality in rod-and-reel fishing, i.e., deep-hooked fish or fish hooked in the gills suffer from higher mortality than fish hooked in the outer parts of the mouth (e.g., Weltersbach and Strehlow, 2013;Lewin et al., 2018). In addition, post-release mortality is species-and fishery-specific and influenced by various abiotic and biotic factors, including water temperature, air exposure, capture depth, fish condition, and predation risk (Wood et al., 1983;Muoneke and Childress, 1994;Bartholomew and Bohnsack, 2005;Hühn and Arlinghaus, 2011). ...
... Hence, the air exposure duration in the present angling experiment was likely well above what most sea trout experience on-site at the coast during a C&R event. In the C&R angling experiment, hooking location clearly influenced air exposure time with deep-hooked fish having longer air exposure than shallow-hooked fish, likely a result of dehooking time for deep-hooked fish which is in line with other studies (Diggles and Ernst, 1997;Lewin et al., 2018;Blyth and Bower, 2022). We also found that air exposure for sea trout caught on lure with treble hooks was longer than for fly-fished sea trout, which is consistent with studies showing that handling time and hence air exposure is shorter for fish caught with flies (e.g., Lamansky and Meyer, 2016; but see Meka, 2004). ...
Sea trout (anadromous brown trout, Salmo trutta L.) is a popular recreational angling target species in the Baltic Sea region and beyond. Across countries, a substantial part of angled sea trout is released after capture either due to management regulations or due to voluntary decisions by the anglers. However, information about post-release impacts of catch and release (C&R) on survival and growth in saline waters is largely missing. We used a flow-through seawater raceway (4-10 °C) to investigate impacts on survival and growth of angled and released sea trout (< 40 cm) up to 29 days post release. Bleeding was common among angled sea trout, but differed between angling treatments, i.e., lure fishing with treble hook (size 4), lure fishing with single hook (size 1/0) and fly fishing with single hook (size 12). However, no mortality and no significant differences in growth were found after a 26-29 days monitoring period among a control group and the three treatment groups, but a small subset (6%) of the angled fish caught on lure had unhealed/infected hooking wounds at the end of the experiment. The results infer that adverse effects of C&R on coastal sea trout due to high post-release mortality or reduced growth can be limited and may not pose a significant problem for sea trout stocks. Nevertheless, further studies are required to corroborate these results under more natural field conditions and at higher water temperatures. In addition, further studies on long-term sublethal impacts of C&R on sea trout are needed.
... Nevertheless, hooking location (anatomical) and associated hooking injuries/bleeding have been identified as one of the most important factors influencing post-release mortality (Muoneke and Childress, 1994;Bartholomew and Bohnsack, 2005;Hühn and Arlinghaus, 2011). Fish that are deep-hooked or hooked in the gills have been shown to suffer from higher mortality than fish hooked in the lips (e.g., Weltersbach and Strehlow, 2013;Lewin et al., 2018). Hooking location depends, amongst others, on the lure and hook type used (Stein et al., 2012;Stålhammar et al., 2014;Weltersbach et al., 2019). ...
... Even though a recent study by Blyth and Bower (2022) indicated high rates of post-release survival and generally limited stress responses to angling events for sea trout, particularly heavy bleeding implies an increased risk for post-release mortality and considering the high release rate of minimum 80 % found in this study we encourage further studies to explore potential lethal and sublethal impacts of C&R on coastal sea trout. Data from this study can help to develop the experimental design, and to adjust experimental results (Lewin et al., 2018;Weltersbach et al., 2018). ...
Sea trout (anadromous brown trout, Salmo trutta L.) is a popular target species for angling in Denmark and many other countries. In most regions, angling for sea trout is regulated by measures such as minimum landing sizes, bag limits or seasonal closures. This can lead to high catch and release (C&R) rates. However, information about angler behavior, C&R practices, hooking locations and level of injury and bleeding, as well as post-release impacts on survival and growth, is largely missing for this species. In this study, we used a citizen science approach to investigate C&R practices of Danish sea trout anglers and to explore drivers for hooking location and bleeding. During the study period from January 2016 to August 2021, 35,826 sea trout caught by angling were reported by users of the citizen science platform. Spin fishing was the most popular angling method (46 %), followed by fly fishing (35 %), bombarda fishing (19 %) and natural bait fishing (1 %). The results confirmed that C&R is a very widespread practice among Danish sea trout anglers, and ≥80 % of all sea trout captured are being released, the majority because they are below the minimum landing size. Twenty-five percent of the caught sea trout bled, and 2 % showed heavy bleeding. Bleeding was related to hooking location (deeply hooked fish bled the most) and to angling method (fly-caught sea trout bled less than fish caught on spin fishing gear), but the role of these two factors varied with fish length. When looking at fish above the legal minimum size, the share of bleeders among the released sea trout was significantly lower compared to harvested fish, suggesting that anglers were more prone to harvest fish that bled. Further studies on lethal and sublethal effects of C&R on coastal sea trout are needed, ultimately aiming to provide fishery managers and anglers with species- and fishery-specific best practice C&R guidelines.
... Catch-and-release angling is known to reduce angling mortality and is often practiced for the management of fish resources (Muoneke and Childress, 1994;Pollock and Pine, 2007). However, some studies have shown that repeated captures of the same individuals can increase the risk of mortality (Bartholomew and Bohnsack, 2005;Levin et al., 2018), or at least cause physiological damage, behavioural change and stress to fish (Davis et al., 2005;Brownscombe et al., 2017). It is thus necessary to investigate how catch-and-release angling affects the vulnerability of released fish to angling in order to accurately evaluate the effectiveness of catchand-release angling for resource management. ...
... Fish caught by anglers are often returned to the water, either by being released or by managing to escape. Released or escaped fish must avoid being recaptured because repeated captures would increase the risk of mortality (Bartholomew and Bohnsack, 2005;Levin et al., 2018), but they must also forage for food to live. If released or escaped fish refrain from eating in the presence of angling gear or learn to recognise some kind of food as aversive, they would lose a chance to take food even when it is safe. ...
Angling gear avoidance learning is a possible factor that contributes to the vulnerability of caught-and-released fish to angling. Whereas past studies suggested angling gear avoidance learning, they were based on large-scale experiments on groups of fish and unable to verify learning accurately. Details of avoidance learning are also unclear. The present study investigated angling gear avoidance learning through a series of individual-based experiments using red sea bream Pagrus major juveniles. Fish avoided angling gear after only one or two catches while showing feeding motivation for pellets, representing avoidance learning for angling gear. Most of the experienced fish avoided krill attached to a fishing line, but not krill alone or pellets presented near the angling gear. Experienced fish were less vulnerable to angling than control fish. Approximately half of the experienced fish kept the memory of angling gear two months after learning. The learning effect through catch and release procedure would reduce catchability and the value of fishery-dependent stock assessments.
... The structural model approach in- dicates that catch is very responsive to effort, with a marginal catch of 3.77 per additional day's fishing (Table 3). Whether an angler retains some fish (subject to bag limit restrictions), or given post-release mortality rates, which are estimated to vary between 3 and 9 % ( Lewin et al., 2018), marginal angling effort has the capacity to impact on stocks. Relying on baseline Model 1, the effect of marginal effort on catch is much more muted. ...
... Consequently, when considering angler effort in stock assessments it is important that effort is stratified by angler proficiency. Even in the context of a full catch & release fishery, angler catches have a direct impact on stocks through post-release mortality rates ( Lewin et al., 2018) so an understanding of catch levels and by whom may affect stock assessments. The geographical range where sea bass are more common is the southern half of the country, which was incorporated in the estimated models with dummy variables for the four southern coastal counties. ...
The relationship between angling effort and catch is well-recognised, in particular that effort influences catch rates. But increased catch, which can be considered an attribute of fishery quality, may influence effort in terms of number of fishing trips. This suggests bi-directional feedback between catch and effort. In many travel cost applications little attention has been given to this endogeneity problem. In this paper we expand the application of structural equation models to address this issue by jointly estimating demand (effort) and catch functions. Using a cross-section dataset of sea bass anglers we propose two separate joint models. First, we include expected catch as an explanatory variable in the demand equation. In the second, we reverse the causality and use the expected number of fishing days as a covariate in the catch function. The two approaches produce similar model estimates, and perform better at predicting anglers' catch and effort than standard models. The findings confirm that sea bass angling is highly valued, with a consumer surplus of about €282-318 per angler per day, though this is likely to be biased upwards. Furthermore higher catches result in more days fished, on average in a 2:1 ratio. Whereas on average, an additional fishing day results in 3-4 additional bass caught.
... As the ICES stock assessment only documents recreational removals, for the purpose of this analysis the number of fish retained and released had to be reconstructed from these removals. This was because release rates of sea bass can be high [13,21] and post-release mortality rates low (5%; [33]), so the number of fish caught (retained and released) was much larger that the removals. Hence, it was important to use the total catch rather than removals for the assessment of welfare, otherwise a large component of the value would be excluded. ...
Economic appraisal of the impacts of fisheries policies is a legal requirement in many global fisheries and is crucial for effective policy making. Some changes in costs and benefits attributable to policy can be assessed through impacts on markets, whilst others are more difficult, as markets may not exist. Analysis is needed to assess value generated by fisheries under different management regimes. The northern stock of European sea bass (Dicentrarchus labrax) has declined rapidly over the past decade leading to management of both the commercial and recreational sectors. Bag limits, closed seasons, and minimum sizes were introduced for recreational fishers, but the social impact of management measures has not been quantified. Here, we use sea bass to demonstrate a method for assessing the impact of management measures on recreational fisher welfare. Through combining stock assessments, individual catch data, and estimates of welfare from a recent choice experiment, differences in welfare under a range of regulatory scenarios were compared. Nine scenarios based on management implemented between 2014 and 2020 were tested. Highest welfare estimates were found with the lowest levels of restrictions and lowest estimates for a no-take fishery, which was driven by retained fish having a higher value than released fish. There was a difference of £ 22.03 million in estimated welfare generated by the recreational sector between these extremes, with the remaining scenarios amid those values. Our results highlight the need for policy makers to carefully consider management options that protect both fish stocks and the welfare of recreational fishers.
... Postrelease mortality is an important consideration for managing open-water C&R fisheries. In numerous openwater settings, mortality estimates have been quantified and are variable among species and contexts (Donaldson et al. 2011;Rapp et al. 2012;Lewin et al. 2018;Weltersbach et al. 2018;Litt et al. 2020). It is currently believed FIGURE 1. Summary of the challenges facing ice-angled fish and the technologies and biological endpoints that can be used to measure fisheriesassociated impacts. ...
Catch and release (C&R) ice fishing is a popular form of recreational angling. At present, there is a considerable deficiency in our understanding of how ice angling affects the physiology, behaviour, and survival of fishes. Thus, the purpose of this review was to summarize our current knowledge of the consequences of winter C&R fishing on fish biology and to identify key knowledge gaps. Our synthesis revealed that in addition to the typical stressors encountered during the open water season from C&R fishing, fishes caught through the ice are subject to several unique challenges including exposure to sub‐zero air temperatures upon landing as well as unique gear types that are not commonly used in the summer (i.e., passive angling techniques). We currently understand that while C&R angling causes a generalized stress response, cold environments may mute or delay these effects, and may also come with additional deleterious consequences such as tissue freezing. Interestingly, reported mortality can be low following release, but can be influenced by gear type, barotrauma, and hooking location. Post‐release behaviours and the spatial ecology of fishes are poorly understood in ice‐angled fishes, but technologies such as telemetry and biologgers, and an intensification of research on the topic is starting to produce new insights in this area. As it stands, research on the consequences of winter C&R angling is largely restricted to a handful of popular sportfish species and are likely not being considered in management and conservation contexts. Given the increasing popularity of the sport, furthering our understanding of C&R impacts in the winter represents a timely and important area of inquiry and can be used to develop more informed and effective C&R guidelines and management practices.
... Such a survey will help promote public policies that involve economic activity as well as provide technical recommendations to For example, in Europe, the European sea bass Dicentrarchus labrax, an important target species for commercial use and recreational fishing along the northeastern Atlantic, Mediterranean, and Black Sea coast (Doyle et al., 2017), has had its fishery stock decreased sharply in some regions in recent years. In order to restore the population of the species, strict management measures were applied, such as the incentive to catch and release, as well as a limitation on the minimum catch length (Lewin et al., 2018), which regardless of the fishing modality increased from 36 to 42 cm (EC, 2015). The results for recreational fishing for D. labrax suggest that its catchability depended on the type of bait and a restriction on the use of live bait may be a viable tool to reduce fishing exploitation during population restoration efforts. ...
A R T I C L E I N F O Keywords: Atlantic forest lambari Capture per unit of effort (CPUE) Deuterodon iguape Litopenaeus schmitti Southeastern coast of Brazil Sportfishing A B S T R A C T This study analyzed the efficiency of lambari Deuterodon iguape as a live bait compared to the artificial bait traditionally used in sea bass fishing (Centropomus parallelus) to demonstrate the viability of its use in recreational fishing. Two boats, with one fisherman each, operated on the Itanhaém river, on the southeastern coast of Brazil, in monthly samples, between October 2019 and September 2020. For statistical analysis, 2x2 and nx2 contingency tables were built and subsequent analysis was performed of the proportions between factors by applying Pearson's chi-squared independence test. It was found that the type of bait used was not associated with catches. In relation to the specimens of sea bass captured, their lengths varied between 20 and 50 cm and the weighed between 400 and 1500 g. The lambari D. iguape is as efficient as artificial bait for bass fishing in inland waters as one economic alternative for sports fisheries. In the context of coastal management, this study shows that the use of live bait of native species produced in a closed recirculation system is a desirable activity from a social and economic point of view, as artisanal fishermen and small rural producers can become suppliers of live baits, contributing to the generation of employment and income.
... While many of the drivers for post-release mortality including barotrauma, air exposure, and hooking location are understood (e.g. Ferter et al., 2015;Lewin et al., 2018), species-specific estimates of post-release mortality are limited. This means that additional post-release mortality and sub-lethal effects studies are needed to ensure that the full impact of MRF is understood and can be used to improve fish welfare in MRF . ...
Marine recreational fisheries (MRF) have important social and economic benefits, but can impact fish stocks and the environment. The diverse and dispersed nature of these fisheries makes them challenging to study; a lack of data has made it more difficult to include them in fisheries management and the varied motivations of fishers makes their response to management measures hard to predict. Research into MRF is growing rapidly, so this themed article set aims to bring together MRF research to highlight the current evidence base and identify future opportunities. New survey methods were presented alongside analyses of existing data, which highlighted issues with methods, reconstruction of missing data, and factors influencing catch and effort. The manuscripts demonstrated the biological and economic impacts of MRF, and its self-subsidizing nature was recognized. Novel approaches for management, including improving compliance, were identified. Finally, the lack of funding for MRF was highlighted. Key research gaps are: governance that embeds MRF in fisheries management; integration of novel approaches and traditional surveys; risk-based approaches to identify impacts; understanding fish welfare; management that balances economic, social, and biological impacts and allows allocation between sectors; and understanding social benefits and their impacts on management and compliance.
... Fishing gear, fish handling techniques, and seasons can have profound effects on mortality rates during handling and discarding of economically valuable species (Davis et al., 2001;Davis, 2002;Davis and Parker, 2004;Cook et al., 2015). Traditionally, estimating delayed mortality involves tagging and recapturing large numbers of individuals, performing tag retention studies, or a combination of acoustic telemetry, captive holding studies and fishing simulation studies (Benoit et al., 2012;Henderson and Fabrizio 2014;Rudershausen et al., 2014;Curtis et al., 2015, Lewin et al., 2018. Such studies can become quite costly and timeconsuming, and thus difficult to replicate. ...
Harvest restrictions (e.g. size, sex or species limitations) that are implemented to maintain sustainable fisheries often result in by-catch, e.g. unwanted non-target catch. By-catch is frequently discarded back into the ocean and assumed to survive. However, discarded fishes can succumb to delayed mortality resulting from accumulated stress from fishing activity, and such mortality can impede sustainability efforts. Quantifying reflex and behavioural impairments is a quick and cost-effective method to predict discard-related mortality in some species. We developed and evaluated the effectiveness of a release condition index, based on a reflex-action mortality prediction (RAMP) model, for predicting delayed mortality of black sea bass (Centropristis striata) caught and discarded by the commercial trap fishery in the Mid-Atlantic Bight. Accumulation of impairments, and therefore release condition index, was strongly correlated with delayed mortality of black sea bass discarded and held in sea cages. This is the first release condition index validation study to predict mortality in black sea bass and could be a useful approach for predicting delayed mortality in the commercial fishery.
... Hence, understanding the sublethal impacts of marine recreational fisheries is important for effective fisheries management. One good example is the European Post-release mortality of recreationally caught sea bass is low (Lewin et al., 2018) and has been included in the assessment of northern sea bass (ICES, 2018b). However, no attempt has been made to assess the sublethal effects of C&R as the impacts on reproduction and growth are difficult to measure, despite the large numbers of fish that are being released. ...
Fish are increasingly exposed to anthropogenic stressors from human developments and activities such as agriculture, urbanization, pollution and fishing. Lethal impacts of these stressors have been studied but the potential sublethal impacts, such as behavioural changes or reduced growth and reproduction, have often been overlooked. Unlike mortality, sublethal impacts are broad and difficult to quantify experimentally. As a result, sublethal impacts are often ignored in regulatory frameworks and management decisions. Building on established fish bioenergetic models, we present a general method for using the population consequences of disturbance framework to investigate how stressors influence ecologically relevant life processes of fish. We partition impact into the initial energetic cost of attempts to escape from the stressor, followed by the energetic impacts of any injury or behavioural change, and their consequent effects on life processes. As a case study, we assess the sublethal effects of catch and release angling for the European sea bass (Dicentrachus labrax, Moronidae), a popular target species for recreational fishers. The energy budget model described is not intended to replace existing experimental approaches but does provide a simple way to account for sublethal impacts in assessment of the impact of recreational fisheries and aid development of robust management approaches. There is potential to apply our energy budget approach to investigate a broad range of stressors and cumulative impacts for many fish species while also using individual-based models to estimate population-level impacts.
... A decline was found in the larger body size classes in all 30 species examined, including common recreational species like cod, pollack and ray species. Lower numbers of larger size classes could cause smaller, younger fish to be at greater risk of being caught which may reduce populations in the long term (Lewin et al., 2018). A reduced chance of catching highly desired large individuals may cause recreational fishers to lose interest in the sport, although research in the United States has suggested that this is not always the case (McClenachan, 2009). ...
Marine recreational fishing is popular globally and benefits coastal economies and people's well‐being. For some species, it represents a large component of fish landings. Climate change is anticipated to affect recreational fishing in many ways, creating opportunities and challenges. Rising temperatures or changes in storms and waves are expected to impact the availability of fish to recreational fishers, through changes in recruitment, growth and survival. Shifts in distribution are also expected, affecting the location that target species can be caught. Climate change also threatens the safety of fishing. Opportunities may be reduced owing to rougher conditions, and costs may be incurred if gear is lost or damaged in bad weather. However, not all effects are expected to be negative. Where weather conditions change favourably, participation rates could increase, and desirable species may become available in new areas. Drawing on examples from the UK and Australia, we synthesize existing knowledge to develop a conceptual model of climate‐driven factors that could impact marine recreational fisheries, in terms of operations, participation and motivation. We uncover the complex pathways of drivers that underpin the recreational sector. Climate changes may have global implications on the behaviour of recreational fishers and on catches and local economies.
... Of course the mortality may be underestimated when causes of death such as predation are excluded during establishment of the correlations, for example while held in tanks. Several studies have assessed vitality scores or RAMP for use in commercial and recreational fisheries and found correlations with survival (Uhlmann et al., 2016;Methling et al., 2017;Van der Reijden et al., 2017) while others found that reflexes did not but injury scores did correlate with survival (Lewin et al., 2018). ...
The EU discard ban and its high-survival exemption exposed our lack of scientific evidence on discard survival in the fisheries. Discard survival is known to be highly variable and influenced by numerous factors, including conditions during the catch, on-board the fishing vessels, and post-discard. Therefore, obtaining unambiguous results in discard survival experiments is challenging. We conducted the first systematic year-round discard survival study of flatfish in the Western Baltic Sea on-board a commercial stern trawler under realistic fishing conditions (13 monthly hauls from May 2015 to May 2016) to test whether delayed mortality can be predicted by vitality scores and reflex action mortality predictor (RAMP) scores in combination with variable conditions during catch, processing, and post-release. The factors vessel type, gear, haul duration, fishing ground, depth, handling time, and processing procedures were kept constant as much as possible. On-board, live individual flatfish were tested for vitality and the presence of reflexes for RAMP, then “discarded” and kept in cages on the bottom of the seafloor for about a week after which the delayed mortality was determined. The proportions of “discarded” plaice, flounder, and dab that were dead after being kept in the cages ranged from 5% to 100%, 0% to 96%, and 33% to 100%, respectively. Higher mortalities occurred in summer-autumn when air and water temperatures were higher, catches smaller, and catches contained smaller proportions of roundfish. Relationships between RAMP scores and mortality probabilities varied substantially across the monthly trials. Indeed, in addition to RAMP or vitality scores and individual reflexes, the factors air and water temperature and catch weight and catch composition were significant in logistic GLMs explaining delayed mortality. Cross-validations indicated that delayed mortality could be predicted by these models with a reasonable accuracy. Nevertheless, the presence of possible confounding effects calls for caution in inferring causality and extrapolating the conclusions on predictability. © International Council for the Exploration of the Sea 2018. All rights reserved.
... The resulting RI scores were significantly different between seasons only for seabass and plaice, and were very low for catshark (less than 10% on average), followed by sole and seabass (around 20% on average), and around 38% for plaice and skates. Although the relationship between the scores and discard survival rate were not established, these results indicate that the vitality of these species was not strongly impacted by these apparently rather favorable fishing conditions (shallow bottoms, short air exposures, light catch weights), in accordance with most of the previous discard survival studies for catshark (Revill et al., 2005;Rodríguez-Cabello et al., 2005), skates (Depestele et al., 2014;Ellis et al., 2017;Enever et al., 2009;Mandelman et al., 2013), seabass (Lewin et al., 2018;Morfin et al., 2017b), plaice and sole (Depestele et al., 2014;Methling et al., 2017;Uhlmann et al., 2016). ...
Two vitality index approaches have been demonstrated to be good proxies of discard survival in similar fishing and environmental conditions: Reflex Action Mortality Predictors combined with injuries (RI) scores that measure the proportion of impaired reflexes and injuries, and a simpler, quicker, but less precise approach based on ordinal categories related to fish body movements and injuries (semi-quantitative assessment, SQA). This study assessed and compared these two approaches for five species (two flatfishes, skates, a seabass and a catshark) discarded in a coastal otter trawl fishery in the Bay of Biscay. All species displayed good vitality status according to both indices and were not very sensitive to the fishing nor their biological conditions. Still, flatfishes were more sensitive to discarding while the catshark was very resistant. Furthermore, depending on species, the impairment of some reflexes and injuries were associated to stressing factors, highlighting the potential of the approach but also the complexity involved in building a relevant score. The SQA index was highly correlated with the RI score and was sensitive to more sources of stressing factors for similar predictive performance. While the relevance of these two approaches should be ultimately determined by the strength and consistency of their association with discard survival, these results suggest that the RI approach was not more effective than SQA despite the extra labour and time involved in collecting the data.
... Recreational fishing has an estimated 1 billion participants worldwide (Cooke and Cowx, 2004) and around 9 million participate in sea fishing in Europe . It is inevitable that any recreational fishing activity will result in species removal as release rates are rarely 100% (Ferter et al., 2013) and some post release mortality in a recreational fishery is unavoidable (Bartholomew and Bohnsack, 2005;Lewin et al., 2018). Recreational fishers tend to target specific species based on the fish attributes such as size, fighting prowess and palatability which may explain why the European seabass (Dicentrarchus labrax, henceforth seabass) is the most sought after fish species of marine recreational fishers (MRF) in several EU countries (Goudge et al., 2010;Herfaut et al., 2012;Armstrong et al., 2013;Monkman et al., 2015;van der Hammen et al., 2016;Hyder et al., 2017). ...
... Accordingly, a study on factors influencing hooking mortality of walleyes (Sander vitreus) found that active angling methods caused less damage to major internal organs and minimized associated hooking mortality (Reeves and Brusewitz, 2007). The authors explained this finding by noting that actively fished lures or baits were less likely to be swallowed by a fish, an observation also made by other studies (Schill, 1996;Schisler and Bergersen, 1996;DuBois and Kuklinski, 2004;Lennox et al., 2015;Lewin et al., 2018). However, even though the present study showed that deep hooking is reduced when using lures it also showed that the use of lures, in particular pilks with treble hooks, may increase the incidence of foul hooking compared to bait angling. ...
Atlantic cod (Gadus morhua) is an important recreational and commercial fisheries target species in the Northern hemisphere. Release rates are high in the recreational fishery due to regulatory and voluntary catch-and-release practice. Although post-release mortality of cod is relatively low, there is potential for further reductions. The most effective way to reduce post-release mortality is to minimize the catch of sublegal fish or non-target species and to reduce hooking injuries by using more selective fishing methods. This study investigated the influence of the lure/bait type on: (1) size of fish, (2) catch and harvest, (3) proportion of bycatch, (4) hooking location, and (5) injury (bleeding) in the western Baltic Sea recreational cod fishery. Data were collected via random onboard sampling of 35 charter vessel angling trips (778 anglers) and during two supplementary studies in the western Baltic Sea. Overall, the median total length was significantly higher for cod caught on artificial lures (39 cm) than for cod caught on natural bait (28 cm), leading to a 43% higher proportion of sublegal (<38 cm) cod for bait than for lure. Median catch-per-unit-efforts (number of captured cod per angling hour) did not differ significantly between lure and bait angling (both: 0.49 cod per hour), whereas the median harvest-per-unit-effort (number of captured cod ≥ minimum landing size (38 cm) per angling hour) was significantly higher for lure (0.24 cod ≥38 cm per hour) than for bait angling (0.06 cod ≥38 cm per hour). The incidence of deep hooking and severe bleeding was significantly higher for bait angling. Furthermore, bait angling significantly increased bycatch of other species dominated by whiting (Merlangius merlangus) and European flounder (Platichthys flesus). Cod anglers can reduce the catch of sublegal cod and non-target species and minimize hooking injuries of released fish by using lures instead of bait in the western Baltic Sea. Thus, voluntary terminal gear recommendations may be an effective tool for anglers and managers to increase selectivity in recreational cod fisheries.
... Anglers often oppose catch and release regulations either because they want to retain fish for the table or due to ethical considerations [65,66]. In this regard a relevant issue is post-release mortality, which is relevant in particular when natural baits are used [67]. In European waters the release of some species of fish, including sea bass, exceeds 60% of the total catch [68], therefore a specific attention to baits and releasing conditions is needed to avoid large cumulative impacts of mortality on fish stocks. ...
Bottom-up approaches to natural resource management are considered to be more effective for conservation than traditional top-down approaches because the policy-making process is legitimised by stakeholders. In particular, when decisions are shared with direct users of the resource, compliance with the law may be achieved more easily and potential sources of conflict averted. However, empirical evidence on this topic is still limited. In this paper, it was investigated how recreational anglers perceive stricter legislation for sea bass fishing, using Ireland as case study. New legislation aims to limit harvest rates to restore a viable bass population following years of declining stocks. Data were collected by means of an angler survey and analysed with a seemingly unrelated ordered probit model. Results suggest that most respondents are willing to trade harvested fish for a healthier and long-term sustainable bass population, suggesting strong compliance with this new law.
... Conversely, using mortality values derived from studies conducted under certain circumstances for discards by commercial fishing or releases by MRF may result in underestimation of catches as country-specific differences in fishing practices will cause different associated mortality rates (e.g. [39,49]). The impact of not taking into account gear type in MRF post-release mortality was likely to be larger in countries allowing static gears (e.g. ...
Marine recreational fishing (MRF) has been shown to substantially contribute to fishing mortality of marine fish. However, European MRF catches are only quantified for a small number of stocks, so it is unclear whether a significant part of fishing mortality is excluded from stock assessments. This study estimated: (i) European MRF removals, which were defined as landings plus dead releases; and (ii) impact at stock level by comparing the percentage contribution to total removal by MRF and commercial fishing. As MRF data were limited for some European countries, catches were reconstructed using a mixture of average release proportions, average fish weights, and extrapolation using the catch per fisher of the nearest country providing catch estimates. Where catch reconstructions exceeded 50%, data were excluded from further analysis. Furthermore, as MRF survey methodology can be variable, semi-quantitative estimates of bias and error were calculated for each stock. Only 10 of the 20 stocks assessed in this study had sufficient MRF data for full reliable estimates. Percentage contribution to total removals (MRF + commercial removals) by MRF ranged between 2% for Atlantic mackerel in the North Sea and Skagerrak and 43% for Atlantic pollack in the Celtic Seas and English Channel. The biomass removed ranged between 297 (± 116) tonnes (Atlantic cod in the western English Channel and southern Celtic seas) and 4820 (± 1889) tonnes (Atlantic mackerel in the North Sea and Skagerrak), but the errors were substantial. Additionally, the bias in the estimated removals was low for most stocks, with some positive biases found. The present study indicates that removals by MRF can represent a high proportion of the total removals for some European marine fish stocks, so inclusion in stock assessments should be routine. To achieve this, regular surveys of MRF are required to collect data essential for stock assessments.
... The EU has protected these ecosystems (Council of the European Union, 1992), but since they have been severely impacted across Europe (Airoldi et al., 2008), it is necessary to successfully monitor the evolution of these important ecosystems over time. Furthermore, the use of non-native worm species reported by Galician anglers (Table 3) should be evaluated and included in regulations, because they have been related to increases in undesired fish mortalities by deep hooking (Alós et al., 2009;Lewin et al., 2018), and to risks for environment (Font and Lloret, 2011;Hyder et al., 2017a). ...
... As the minimum landing size was increased from 36 cm to 42 cm, an adjusted discard rate was calculated based on the size composition of landings for each gear (as well as assumptions about avoidance and parameters for survivability). The adjusted bass discard rate can be expressed as: where ADRB is an adjusted discard rate of bass, g is the gear, DRB is the recorded discard rate of bass, LM is the current level of landings in the range of the change in minimum landing size, and M is the rate of mortality of discards (90% for trawls, 80% for nets, 20% for hooksall estimated from previous qualitative descriptions) [69,70]. The same survivability parameters are used for the indicator of total discards, where ADR is the adjusted discard rate of all species and DR is the recorded discard rate of all species. ...
Transparent, performance-based approaches to allocating fishing opportunities are required for signatories to the Aarhus Convention and the European Union's (EU) Member States via the Common Fisheries Policy. The lack of an operational framework to support this requirement means such a system is seldom explicitly used. Using the English commercial sea bass (Dicentrarchus labrax) fishery as a case study, operationalisation of this policy requirement is evaluated using a Multi-criteria decision analysis (MCDA) framework. MCDA is a decision making tool allowing users to explicitly evaluate complex, potentially conflicting, criteria, enabling wider costs and benefits to be considered. The sea bass fishery was selected as the dramatic stock decline since 2010 has meant difficult policy choices regarding the allocation of scarce fishing opportunities between different user groups. To inform the MCDA, the three main English sea bass fishing methods (nets, hooks, and trawls) are evaluated across thirteen social, economic, and environmental criteria to generate a performance score. Importance weightings for each criterion, developed from 50 surveys of fishers, industry representatives, managers, non-governmental organisations, and the wider public, are used to combine these performance scores generating an overall score for the MCDA. Results show that regardless of stakeholder group questioned, hooks achieve the highest MCDA performance, followed by nets, and then trawls. This suggests that taking a performance- based approach to the allocation of fishing opportunities in the English fishing fleet have a prioritisation by fishing type. MCDA could be used to promote transparency, objectivity and social, environmental and economic sustainability into European and UK fisheries.
... This could be achieved by collecting country-specific data on eel angling practices, e.g., by using representative national recreational fisheries surveys asking questions regarding hook type and size used, and proportion of deep-hooked or bleeding fish in the recreational eel fishery. This information can then be used to extrapolate the experimental post-release mortality rates to provide country-specific post-release mortality rates for use in stock assessments (Capizzano et al., 2016;Lewin et al., 2018). ...
Several anguillid eel species have experienced severe population declines over the past decades, particularly the European eel (Anguilla anguilla), which is listed as critically endangered by the International Union for Conservation of Nature. To reduce fishing mortality, many European countries have introduced strict recreational eel fishing regulations increasing regulatory catch-and-release (C&R) practice. Despite high release rates, only limited information exists on the potential consequences of C&R on eels. A field experiment was conducted with pre-tagged eels in a semi-natural environment to investigate lethal and sublethal impacts of C&R. The experiment was combined with a citizen science study evaluating the effects of different hooks on catch rates, fish size, and hooking location to develop best practice guidelines. Short-term mortality (≤72 h) ranged from 0.0-18.2%, and adjusted long-term mortality (> 72 h) from 0.0-46.2% depending on treatments, resulting in adjusted total mortality rates between 8.4% and 64.4% at the end of the study period (≥43 d). The only significant predictor of mortality was the occurrence of bleeding from hooking injuries. Deep hooking was common, and only few deep-hooked eels for which the fishing line was cut and the hook left in place shed the hook after release. However, no significant effect of C&R on eel condition was found. The citizen science study showed that anglers can significantly decrease the catch of small eels, and thus release rates, by using large J-hooks. Furthermore, large J-hooks or circle hooks reduced the likelihood of deep hooking compared to small J-hooks. Post-release mortality of eels caught in recreational fisheries needs to be considered in future stock assessments and management plans to ensure conservation of the European eel. This study also highlights the strength of combining citizen science with experimental studies to develop best practice guidelines promoting fish conservation.
The introduction of high survivability exemptions from the EU landing obligation has raised
questions on how they relate to ICES stock advice and the management of quotas (TACs). Where discard rates are high, and survival rates are limited, substantial quantities of dead discards are generated. On the other hand, high survival rates may result in limited impacts of discarding despite high discard rates. Therefore, to achieve agreed levels of fishing mortality, dead discards should be accounted for in the stock assessment and the advice derived from it. The inclusion of discard survival in stock assessments has wider application also since it can improve estimates of fishing mortality and in turn enhance scientific advice on fishing opportunities.
This ICES workshop, WKSURVIVE, was established to explore and progress the inclusion of discard survival in stock assessments. Participants consisted of researchers with expertise in conducting discard survival experiments and researchers with expertise in stock assessments. The workshop successfully reviewed the approaches taken in existing ICES stocks assessments to integrate discard survival estimates. Three cases were identified: plaice (Pleuronectes platessa) in Division 7.a (Irish Sea), several Norway lobster (Nephrops norvegicus) Functional Units (FUs), andsea bass (Dicentrarchus labrax) in divisions 4.b, 4.c, 7.a, and 7.d–h (although only for recreational catches in this last case). These cases are reviewed and described in the report.
WKSURVIVE identified case study ICES stock assessments for which there is management interest to include discard survival, and for each one mapped to it relevant and robust discard survival evidence. Based on the type of assessment and the associated discard survival evidence, the group agreed on recommendations on the inclusion of discard survival for each stock assessment. A table including the stock assessments, survival evidence, and stock-specific recommendations was a key output from this workshop. The group also reviewed other case studies where the implications of discard survival on stock estimates and reference points are actively being explored, but not yet used in the assessments.
The workshop also included a small seminar with a series of presentations on recent and current research activity related to discard survival. Ten presentations were made and included, among others, the discard survival of Nephrops, sole, rays, and small pelagics. This continues to be an active research area and there is currently substantial attention on the discard survival of rays in particular, which links to the EU conditional survivability exemption for skates and rays and associated evidence roadmap. A summary of each area of research activity is presented here.
The importance of social and economic factors, in addition to biological factors, in fisheries management is being increasingly recognised. However, exploration of trade-offs between biological, social, and economic factors under different sustainable catch limits for recreational and commercial fisheries is limited, especially in Europe. The European sea bass (Dicentrarchus labrax) is valuable and important for both commercial and recreational fisheries. Stocks have rapidly declined and management measures have been implemented, but trade-offs between social, biological, and economic factors have not been explicitly considered. In this study, a system dynamics model framework capturing biological and economic elements of the European sea bass fishery was developed and refined to incorporate a catch limit reflecting sustainable fishing with adjustable partition between recreational and commercial sectors, under low, medium, or high recruitment. Model outputs were used to explore the relative impact of different catch allocations on trade-offs between biological sustainability and economic impact when recruitment was limiting or not. Recruitment had a large impact on the fish population dynamics and the viability of the sectors. At high and moderate recruitment, management contributed to stock sustainability and sector economic impact, but recruitment is important in determining the balance between sectors.
This report summarises a review of international fisheries management regimes. The review summarises the available information on specified topics related to fisheries management in a number of specified study countries. The topics were a) Fisheries management; b) Quota allocation and trading; c) Enforcement; d) Science; e) Data collection; f) Access arrangements; g) International investment in the fishery; h) The role of industry; i) Discard policy; j) the ecosystem based approach to fisheries management, and k) Marine recreational fisheries. The management regimes under review were those of Iceland, Norway, the Faroe Islands, Australia, New Zealand, the USA and Canada.
In 2019, Europe will adopt a no-discards policy in fisheries. This entails the landing of captured species unless strong evidence is provided supporting their survival and recovery after fishing. Thus, research on this topic is gaining momentum. Bottom-trawling, as a non-selective fishing method, is characterized by a high proportion of discards including vulnerable key species, such as demersal sharks. Their survival may also depend on capture depth. By paralleling onboard and laboratory experiments with the small-spotted catshark, Scyliorhinus canicula, we offer a robust experimental design to assess the survival of discarded sharks. Catsharks were captured by bottom-trawling at two depths (shallow ~89 m and deep ~479 m). Blood samples were collected following trawl capture and analyzed for stress biomarkers (lactate, osmolality, phosphate, urea). During recovery in onboard tanks, behavior was video-recorded and fish were re-sampled after 24 h. A second experiment was conducted in laboratory facilities to simulate air-exposure after trawling and to analyze the physiological recovery. Our results showed that 95.7% of the animals survived 24 h after trawling. We confirmed that trawling elicited acute stress responses in catshark but that they managed to recover. This was demonstrated by lactate concentrations that were 2.6 mM upon capture, but recovered to assumed baselines after 24 h (0.2 mM). Non-invasive video monitoring revealed behavioral differences with depth, whereby those captured at 89 m depth required longer to recover than those captured at 479 m depth. Implementation of standardized survival studies by fishery managers can benefit from holistic physiological approaches, such as the one proposed here.
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, expenditures, and catches of two widely targeted species were synthesized to provide European estimates of MRF and placed in the global context. Uncertainty assessment was not possible due to incomplete knowledge of error distributions; instead, a semi-quantitative bias assessment was made. There were an estimated 8.7 million European recreational sea fishers corresponding to a participation rate of 1.6%. An estimated 77.6 million days were fished, and expenditure was €5.9 billion annually. There were higher participation, numbers of fishers, days fished and expenditure in the Atlantic than the Mediterranean, but the Mediterranean estimates were generally less robust. Comparisons with other regions showed that European MRF participation rates and expenditure were in the mid-range, with higher participation in Oceania and the United States, higher expenditure in the United States, and lower participation and expenditure in South America and Africa. For both northern European sea bass (Dicentrarchus labrax, Moronidae) and western Baltic cod (Gadus morhua, Gadidae) stocks, MRF represented 27% of the total removals. This study highlights the importance of MRF and the need for bespoke, regular and statistically sound data collection to underpin European fisheries management. Solutions are proposed for future MRF data collection in Europe and other regions to support sustainable fisheries management.
For many marine migratory fish, comparatively little is known about the movement of individuals rather than the population. Yet, such individual-based movement data is vitally important to understand variability in migratory strategies and fidelity to foraging locations. A case in point is the economically important European sea bass (Dicentrarchus labrax L.) that inhabits coastal waters during the summer months before migrating offshore to spawn and overwinter. Beyond this broad generalisation we have very limited information on the movements of individuals at coastal foraging grounds. We used acoustic telemetry to track the summer movements and seasonal migrations of individual sea bass in a large tidally and estuarine influenced coastal environment. We found that the vast majority of tagged sea bass displayed long-term residency (mean, 167 days) and inter-annual fidelity (93% return rate) to specific areas. We describe individual fish home ranges of 3 km or less, and while fish clearly had core resident areas, there was movement of fish between closely located receivers. The combination of inter-annual fidelity to localised foraging areas makes sea bass very susceptible to local depletion; however, the designation of protected areas for sea bass may go a long way to ensuring the sustainability of this species.
Black sea bream Spondyliosoma cantharus is highly valued for its sporting and eating qualities. Due to its inshore spawning aggregations and male nest guarding behaviors, it is considered vulnerable to over-exploitation via recreational angling. Accordingly, greater uptake of the practice of catch-and-release (C&R) may provide some potential to limit the effects of angling on populations. Thus, the consequences of C&R for 40 S. cantharus (mean length 306 ± 10 mm) were assessed. Fish were sampled following their capture from charter boats by recreational anglers with varying levels of skill and experience. Of these fish, 17% were deeply hooked (e.g. in esophagus) and considered at high risk of post-release mortality (PRM). Blood lactate levels ranged between 0.40 and 2.60 mmol l − 1 (mean ± SE: 1.25 ± 0.09) and were significantly and positively correlated with fight time. Reflex impairments were observed in 32% of the catch, also suggesting an elevated probability of PRM. Hook damage was the only significant predictor of reflex impairment. The dominance of males (89%) across the catches highlighted the potential for additional indirect impacts of angling via the predation of eggs by conspecifics in the vacated nests of captured males. These results are discussed within the context of post-release performance of individual S. cantharus, the potential for C&R to limit impact at the population level and a need to consider future regulation of the fishery to ensure sustainability of stocks.
Research of catch-and-release fishing has included air exposure time as a contributing factor in the lethal and sublethal impacts to fish. However, to our knowledge, no studies have observed the amount of time anglers actually expose fish to air when recreationally fishing. We observed 280 anglers on several waters where catch and release was commonly practiced for trout and timed how long they exposed trout to air before releasing them back to the water. We also noted several angling characteristics to evaluate whether they influenced air exposure times, including the type of gear (fly, lure, bait), fishing on foot or from a boat, handling method (hand, net), and a subjective measure of trout size (small, medium, large). The longest continuous interval that anglers exposed trout to air averaged 26.1 s (range, 0-160 s), and only 4%of the anglers held fish out of thewater continuously for >60 s. Total air exposure averaged 29.4 s, ranged from0 to 165 s, and differed from the longest air exposure by only 3.3 s because most of the released trout (78%) were held out of the water only one time. Anglers who handled trout by hand (rather than using a landing net) and used flies (rather than bait or lures) held fish out of water for less time. Larger trout were exposed to air longer (x = 36.0 s) than small (x = 22.5 s) or medium-sized (x = 27.1 s) trout. However, no angling characteristic increased air exposure by more than 14 s. Fight time averaged 53.0 s and ranged from 7 to 128 s.We conclude that from an air exposure perspective, most of the trout released by anglers in our study were not exposed to air for times that would cause mortality or substantively increase sublethal effects from catch and release.
White marlin, a highly migratory pelagic marine fish, support important commercial and recreational fisheries throughout their
range in the tropical and subtropical Atlantic Ocean. More than 10 000 individuals can be caught annually in the United States
recreational fishery, of which the vast majority are captured on circle hooks and released alive. The probability of post-release
mortality of white marlin released from circle hooks has been documented to be <0.02, but the associated physiological stress
resulting from capture and handling techniques has not been characterized despite its importance for understanding the health
of released fish. We examined the physiological response of 68 white marlin caught on circle hooks in the recreational fishery
and followed the fate of 22 of these fish with pop-up satellite archival tags programmed to release after 30 days. Measures
of plasma sodium, chloride, glucose and lactate concentrations taken from fish that were briefly and consistently (mean =
120 s, standard deviation = 40 s) removed from the water increased with angling time, but post-release mortality was inversely
related to angling time. The probability of post-release mortality was predicted by elevated plasma potassium concentrations
and was more than 10 times greater than has been previously reported for white marlin caught on circle hooks that were not
removed from the water. This disparity in estimates of post-release mortality suggests that removal of fish from the water
for physiological sampling greatly heightens stress, disrupts homeostasis and thus increases the probability of post-release
mortality. Our results demonstrate that elevated concentrations of plasma potassium predict mortality in white marlin and
that the probability of post-release mortality is highly dependent on post-capture handling procedures.
The European eel (Anguilla anguilla) is a commercially and recreationally important fishery target species. In the last decades, the eel has experienced dramatic stock declines and has been listed as critically endangered. To reduce fishing mortality, several European countries have closed the fishery or introduced stricter management measures which increase the likelihood of catch-and-release in the recreational fishery. This study investigated hook shedding mechanisms of deep-hooked, line-cut eels via radiography, and quantified hook shedding rates, post-release mortality and sub-lethal effects in captivity. Eels were caught with four different hook treatments, monitored in a tank for 23 weeks, and radiographed 0, 1, 3, 10, 24, 54, 115 and 163 days after capture. After 163 days, total hook shedding rate was significantly higher for smaller hooks (41.2%) compared to larger hooks (0.0%), and increased with fish length. Post-release mortality rates ranged between 27.3% and 50.0% after 23 weeks (not adjusted for handling and holding) and did not differ significantly between hook treatments.The majority of dead eels showed gastric perforations caused by the hooks leading to internal haemorrhaging and the intrusion of digestive fluids into the body cavity inducing lethal degradation and inflammation of vital organs. Anglers are encouraged to minimise bycatch of eel in countries where eel harvest is prohibited. Anglers targeting eel should use selective and appropriate fishing gears, baits and tactics (e.g. very large hooks, immediate hook setting after a bite) to reduce deep hooking and the catch of undersized eels, ultimately promoting the eel's conservation.
Recreational creel survey data from 28,923 intercepts collected from Biscayne National Park, Florida and surrounding waters were analyzed for January 1976 through July 1991, prior to disruptions caused by Hurricane Andrew in 1992. A total of 261.268 fish and shellfish representing 170 species or higher taxa were recorded. The average trip landed 9.03 fish and/or shellfish. Mean annual landings per angler were 4.77 fish/angler/ trip (from 3.80 in 1991 to 5.83 in 1981) and dropped significantly for each of the 2 years following Florida's adoption of multiple new minimum size limits in 1985 and 1990. The relative contribution to total numerical landings by recreational party type were: Skilled anglers (34.0%), food (19.8%), family (14.5%), novice (11.5%), spearfishing (10.3%), lobstering (9.6%), and other (0.3%). Five species or higher taxa accounted for more than 50% of total landings by number: White grunt, Haemulon plumieri, 15.8%; spiny lobster, Panulirus argus, 10.6%: Gray snapper. Lutjanus griseus, 10.6%; unidentified grunts. Haemulon spp., 7.3%; and dolphin. Coryphaena hippurus, 6.6%. An average of 4.39 fish or shellfish were reported released per trip. Five taxa accounted for 67% of all releases. Lobster divers reported the highest average release rate (5.73 per trip) and spearfishing the lowest (0.70 per trip). The ratio of releases to landings was 0.49:1 for all taxa, but ranged from 0.03:1 for dolphin to 1.19:1 for unidentified grunts. Spearfishing accounted for 12.0% of the total fishing trips sampled but only 10.3% of the total number organisms landed and 7.6% of all organisms caught. Hogfish, Lachnolaimus maximus, accounted for 49% of total spearfishing landings (13,286 of 27.015) and 84.3% of total 15,762 hogfish landed.
European grayling (Thymallus thymallus) is a popular recreational fish that may be lifted out of the water to facilitate hook removal or for admiration. To evaluate the effects of air exposure and angling-induced exhaustive exercise on released grayling condition, we assessed blood physiology and reflexes of grayling after angling and air exposure in the subarctic River Lakselva (Norway) at midsummer temperatures (i.e., 17–18 °C). Blood samples were drawn 30 min after angling and analyzed for lactate anions, glucose, sodium ions, and pH. Reflex impairment was determined with orientation and tail grab reflex action assessments immediately after landing, after air exposure, and after 30 min holding. Blood physiology did not indicate an exacerbating effect of air exposure relative to just angling-induced exercise, but significant and prolonged reflex impairment was associated with the 120 s air exposure interval. Anglers must take care to minimize air exposure to adhere to best handling practices.
In this study we describe a two-phase survey design and implications of approaches to non-response adjustments on estimates of the total catch taken by Dutch recreational fishers, including marine catches for Atlantic cod and European seabass and European eel in freshwater. The survey comprised three main elements which were executed online: a screening survey to estimate the characteristics of the population of recreational fishers (number of fishers, their demographic profile and stated fishing avidity); a 12 month logbook survey to estimate effort and catch rates; and non-response follow up surveys to adjust for non-response. A response rate of 80% was achieved for the screening survey and, following non-response adjustment and limited data imputation, 89% for the logbook survey. Some logbook participants reported no fishing activity (drop-outs) and were removed from the analysis. In addition, logbook data were weighted in accordance with the stated avidity distribution in the population to address potential response bias based on avidity. Imputation and weighting for avidity influenced the catch estimates a little, whereas the removal of the fisher drop-outs was influential, linked to the rates of fisher drop-outs (18% for freshwater and 55% for marine fishers). Freshwater recreational fishing was more popular than marine fishing; 9.7% of the Dutch population participating in the former and 4.1% fishing in marine waters. In total an estimated 53.6 million freshwater fish were caught (2.6 million retained) and 13.6 million marine fish were caught (9.6 million retained). Respective catch estimates for Atlantic cod, European seabass and European eel were 0.70, 0.35 and 1.23 million fish (0.53, 0.23 and 0.34 million retained). We conclude that the survey design using an online panel may serve as an example for future surveys because of its efficacy to collect a rich set of data at relatively low cost compared to traditional survey methods.
Atlantic cod (Gadus morhua) caught in recreational fisheries are commonly released, often with barotrauma after rapid decompression. Mouth-hooked, non-bleeding cod kept in a floating net pen showed mortalities ≥40% when angled from >50 m depth, likely because of cumulative stress from ongoing barotrauma and exposure to warm surface water. In a natural setting, however, cod have the opportunity to descend after release and are not restricted to the surface. In a follow-up study, 97.8% of similarly selected cod managed to dive following immediate release, whereas 2.2% were floaters. No mortality was observed for divers kept in cages, which were lowered to capture depth for 72 h. While the floaters would likely have died in a natural setting, no mortality was observed when they were recompressed and kept at capture depth for 72 h. The occurrence of swim bladder ruptures, swollen coelomic cavities, venous gas embolisms, and gas release around the anus was significantly influenced by capture depth (range 0–90 m). A supplementary radiology study showed inflated swim bladders in 87% of the cod after 72 h, and most barotrauma signs had disappeared after 1 month. This study encourages investigation of survival potential for physoclistous species when high mortalities are assumed but undocumented. Matching natural post-release and containment environment is essential in the experimental setup, as failure to do so may bias survival estimates, particularly when a thermocline is present. Assuming minimal predation, short-term mortality of cod experiencing barotrauma is negligible if cod submerge quickly by themselves and are otherwise not substantially injured. Survival of floaters may be increased by forced recompression to capture depth. Sublethal and long-term impacts of barotrauma remain to be studied. To ensure that cod have sufficient energy to submerge, anglers are encouraged to avoid fighting the fish to exhaustion and to minimize handling before release.
We investigated short-term effects (up to 24 h) of air exposure and confinement, and long-term effects (up to 11 days) of confinement, to elucidate signalling pathways in the stress response of gilthead sea bream Sparus aurata L. Plasma glucose and lactate were taken as indicators of sympathetic activation, and-melanocyte stimulating hormone (-MSH), adrenocorticotrophic hormone (ACTH) and cortisol as indicators of activation of the brain– pituitary–interrenal (BPI) axis. Air exposure for 3 min resulted, within 30 min, in an increase in plasma concentrations of cortisol,-MSH, glucose, lactate, osmolality and plasma Na, Cl and Mg. Plasma ACTH and-endorphin and plasma K, Ca and P did not change. We conclude that air exposure mainly activates the brain– sympathetic–chromaffin cell (BSC) axis. In fish confined at a density of 70 kg/m 3 (compared with 4 kg/m 3 in controls), cortisol, ACTH and-MSH increased within 1 h, indicating activation of the BPI axis. Plasma glucose, Na, Cl and Mg increased with an 8 h delay compared with the response to air exposure. No changes in plasma lactate, osmolality, K, Ca and P were observed. Long-term confinement induced a biphasic cortisol response with peaks at 1 h and at 2 and 3 days. A gradual increase in plasma-endorphin concentrations peaked at 7 days; the concentration of-MSH increased rapidly within 1 h and then declined to control values 4 days after the onset of confinement. No changes in ACTH were detected. Our data provide evidence that a stressor-specific activation of the BSC and BPI axes may occur in Sparus aurata.
Fisheries interactions that result in the capture and release of fish can cause behavioral impairments that increase the risk of postrelease predation. Increased predation risk has been attributed to reduced swimming capabilities; however, the role of refuge (structural shelter) use is still poorly understood. We examined the effect of fishing-related stressors on the ability of subadult Great Barracuda Sphyraena barracuda to attain refuge in an experimental wetland in Eleuthera, The Bahamas. Twenty-two Great Barracuda were either treated as controls with minimum stress, chased to exhaustion, or chased to exhaustion and air exposed for 90 s. Reflex action mortality predictors (RAMP) including ability to maintain equilibrium and bursting response were assessed prior to release at a standardized location. The prop roots of red mangrove Rhizophora mangle provided refuge about 5 m from the release point. Great Barracuda were visually monitored for up to 30 min postrelease to quantify behavior (resting, swimming, directional changes) and the time when refuge was reached. The RAMP scores increased with the degree of stressor, and fish in both fishing-related stressor treatments took significantly longer to reach refuge than control fish, while air exposed fish took significantly longer than fish that were only chased. Prior to reaching refuge, fish exposed to fishing-related stressors spent less time swimming, and changed directions more frequently than control fish, indicating that impaired locomotory capabilities and disorientation inhibited refuge use. The inability to find refuge after an acute stressor such as capture and release fisheries may be an important factor contributing to postrelease mortality for relevant species.Received September 23, 2013; accepted December 6, 2013
High biological activity causes a distinct seasonality of surface water pH in the North Sea, which is a strong sink for atmospheric CO2 via an effective shelf pump. The intimate connection between the North Sea and the North Atlantic Ocean suggests that the variability of the CO2 system of the North Atlantic Ocean may, in part, be responsible for the observed variability of pH and CO2 in the North Sea. In this work, we demonstrate the role of the North Atlantic Oscillation (NAO), the dominant climate mode for the North Atlantic, in governing this variability. Based on three extensive observational records covering the relevant levels of the NAO index, we provide evidence that the North Sea pH and CO2 system strongly responds to external and internal expressions of the NAO. Under positive NAO, the higher rates of inflow of water from the North Atlantic Ocean and the Baltic outflow lead to a strengthened north-south biogeochemical divide. The limited mixing between the north and south leads to a steeper gradient in pH and partial pressure of CO2 (pCO2) between the two regions in the productive period. This is exacerbated further when coinciding with higher sea surface temperature, which concentrates the net community production in the north through shallower stratification. These effects can be obscured by changing properties of the constituent North Sea water masses, which are also influenced by NAO. Our results highlight the importance of examining interannual trends in the North Sea CO2 system with consideration of the NAO state.
Fisheries statistics are known to be underestimated, since they are mainly based on information about commercial fisheries. However, various types of fishing activities exist and evaluating them is necessary for implementing effective management plans. This paper assesses the characteristics and catches of the French European sea bass recreational fishery along the Atlantic coasts, through the combination of large-scale telephone surveys and fishing diaries study. Our results demonstrated that half of the total catches (mainly small fish) were released at sea and that the mean length of a kept sea bass was 46.6 cm. We highlighted different patterns of fishing methods and type of gear used. Catches from boats were greater than from the shore, both in abundance and biomass, considering mean values per fishing trip as well as CPUE. Spearfishers caught the highest biomass of sea bass per fishing trip, but the fishing rod with lure was the most effective type of gear in terms of CPUE. Longlines had the highest CPUE value in abundance but not in biomass: they caught numerous but small sea bass. Handlines were less effective, catching few sea bass in both abundance and biomass. We estimated that the annual total recreational sea bass catches was 3,173 tonnes of which 2,345 tonnes were kept. Since the annual commercial catches landings were evaluated at 5,160 tonnes, recreational landings represent 30% of the total fishing catches on the Atlantic coasts of France. Using fishers' self-reports was a valuable way to obtain new information on data-poor fisheries. Our results underline the importance of evaluating recreational fishing as a part of the total amount of fisheries catches. More studies are critically needed to assess overall fish resources caught in order to develop effective fishery management tools.
Atlantic cod (Gadus morhua) is one of the most important commercial and recreational target species in European marine waters. Recent recreational fisheries surveys revealed that recreational cod catches and release rates are substantial compared to the commercial fishery, particularly in the western Baltic Sea. Despite high release rates, no literature exists exploring the post-release mortality of cod and potential sublethal effects after catch-and-release in recreational fisheries. This study investigates (i) the post-release mortality of undersized cod, (ii) potential factors affecting mortality, and (iii) consequences of the catch-and-release process on cod. During four experimental trials, western Baltic Sea cod were angled from a charter vessel and thereafter observed together with control fish in netpens for 10 d at holding temperatures between 6.2 and 19.8°C. Adjusted mortality rates for angled cod ranged from 0.0–27.3% (overall mean 11.2%). A logistic regression analysis revealed that bleeding and holding-water temperature were the only significant
predictors of mortality. Slow hook injury healing ( > 10 d) and bacterial wound infections were observed in some surviving cod. The results will help to increase the accuracy of recreational cod removal estimates and thereby improve the management of western Baltic cod stock.
A comprehensive, but simple-to-use software package for executing a range of standard numerical analysis and operations used in quantitative paleontology has been developed. The program, called PAST (PAleontological STatistics), runs on standard Windows computers and is available free of charge. PAST integrates spreadsheettype data entry with univariate and multivariate statistics, curve fitting, time-series analysis, data plotting, and simple phylogenetic analysis. Many of the functions are specific to paleontology and ecology, and these functions are not found in standard, more extensive, statistical packages. PAST also includes fourteen case studies (data files and exercises) illustrating use of the program for paleontological problems, making it a complete educational package for courses in quantitative methods.
In the current study, we simulated different components of a live-release angling tournament (angling, live-well confinement, and weigh-in) to determine the relative physiological significance of these tournament components for largemouth bass Micropterus salmoides. Our results indicated that depletions of white muscle energy stores and accumulations of muscle lactate (i.e., a large metabolic disturbance) are the most important consequences of live-release angling tournaments for largemouth bass. This study also showed that there are two distinct components of a live-release tournament that cause a metabolic disturbance in largemouth bass: angling and the weigh-in. While the physiological consequences of angling are already well understood, this is the first study to show that the weigh-in portion of a live-release tournament also causes a large anaerobic disturbance in largemouth bass. In our simulation, the weigh-in resulted in a 75% decrease in white muscle phosphocreatine, a 46% decrease in ATP, and a 62% decrease in glycogen relative to control largemouth bass. The weigh-in simulation also caused the lactate concentration in white muscle to increase by about sevenfold relative to control fish and resulted in significant changes to cardiac function. Based on these results, subsequent experiments were performed to determine the main factor(s) responsible for the metabolic disturbance that results from the weigh-in. These experiments demonstrated that the period of air exposure during the weigh-in was a major cause of this disturbance. We recommend that tournament organizers minimize the air exposure that largemouth bass receive during the weigh-in to improve the physiological condition of released tournament-caught fish.
Although a great deal of effort has been expended to try to understand the consequences of fishing-induced selection by commercial fisheries, relatively little effort has been put into trying to understand the selective effects of recreational angling. We conducted a long-term selection experiment to assess the heritability of vulnerability to angling in largemouth bass Micropterus salmoides. Three successive generations of artificially selected largemouth bass were produced from a single experimental study population. Within each generation, individual adult largemouth bass were identified as having either high or low vulnerability to angling through a series of controlled catch-and-release angling trials. Individuals of each vulnerability group (high and low) were then selected from that population for breeding to produce the next generation. The response to selection for vulnerability to angling increased with each generation; that is, the magnitude of the difference between the high- and low-vulnerability groups of fish increased with each successive generation. Realized heritability was calculated as 0.146 (r = 0.995), indicating that the vulnerability of largemouth bass to angling is indeed a heritable trait. Our results indicate that recreational angling has the potential to alter the gene pool of wild fish populations, which may indirectly affect population characteristics such as survival, growth rate, and reproductive output as well as directly affecting angling success rates.
Recreational harvests of bluefish Pomatomus saltatrix along the U.S. coast from Maine to Florida exceed commercial harvests, and in recent years about 60–70% of angler-captured fish are released alive. The proportion of fish that survive hooking, handling, and release back to the ocean is unknown; however, if catch-and-release mortality is high, it may represent a significant component of the overall bluefish mortality rate. We estimated long-term (21-d) hooking mortality rates of field-captured bluefish and investigated the effects of various factors on postrelease mortality. Age, length, and the occurrence of bleeding were significant factors associated with catch-and-release mortality, which we estimated to be 38.8%. About 65% of the mortality was initial mortality, and the remainder was delayed mortality. We also performed a laboratory study to examine the physiological response of bluefish to two independent processes (hooking and release versus transfer in coolers to the laboratory) relevant to the field study. Laboratory-held fish that were hooked and released exhibited elevated concentrations of potassium in their blood, suggesting that they experienced either an osmotic imbalance or cellular damage. Laboratory-held fish exposed to the transfer treatment only exhibited osmotic imbalance (elevated plasma sodium concentration) and evidence of anaerobic metabolism (elevated plasma lactate concentration). Our findings indicate that bluefish age and size contribute to variable levels of metabolic stress and that delayed postrelease mortality is considerable.
Despite the growing number of recreational anglers targeting white seabass Atractoscion nobilis in California, no information is available on the mortality rates of juveniles following catch and release. We captured juvenile white seabass (430–577 mm total length) with 4/0 offset circle hooks (n = 113) or 4/0 J-type hooks (n = 108) or with a net (control, n = 30) to investigate the effect of hook type on anatomical hook location. We also examined how hook location affected growth and survival for 90 d following release. Offset circle hooks penetrated the lip region significantly more frequently (73%) than did J-type hooks (41%). Hook location was directly correlated with mortality; all mortalities involved hook damage to the visceral region. A 10% postrelease mortality rate was observed for fish caught on both offset circle and J-type hooks. All mortalities occurred within 5 d postrelease. Survival was enhanced when deeply embedded hooks were left in place rather than removed from the visceral tissue. Hook-caught fish showed no reduction in growth when compared with control fish, but deeply hooked fish grew at a significantly lower rate than did fish hooked in the mouth. Angler success rates did not differ significantly between hook types. We recommend that catch-and-release mortality be incorporated into the management plan for white seabass.
Fishery collapses cause substantial economic and ecological harm, but common management actions often fail to prevent overfishing. Minimum length limits are perhaps the most common fishing regulation used in both commercial and recreational fisheries, but their conservation benefits can be influenced by discard mortality of fish caught and released below the legal length. We constructed a computer model to evaluate how discard mortality could influence the conservation utility of minimum length regulations. We evaluated policy performance across two disparate fish life-history types: short-lived high-productivity (SLHP) and long-lived low-productivity (LLLP) species. For the life-history types, fishing mortality rates and minimum length limits that we examined, length limits alone generally failed to achieve sustainability when discard mortality rate exceeded about 0.2 for SLHP species and 0.05 for LLLP species. At these levels of discard mortality, reductions in overall fishing mortality (e.g. lower fishing effort) were required to prevent recruitment overfishing if fishing mortality was high. Similarly, relatively low discard mortality rates (>0.05) rendered maximum yield unobtainable and caused a substantial shift in the shape of the yield response surfaces. An analysis of fishery efficiency showed that length limits caused the simulated fisheries to be much less efficient, potentially exposing the target species and ecosystem to increased negative effects of the fishing process. Our findings suggest that for overexploited fisheries with moderate-to-high discard mortality rates, reductions in fishing mortality will be required to meet management goals. Resource managers should carefully consider impacts of cryptic mortality sources (e.g. discard mortality) on fishery sustainability, especially in recreational fisheries where release rates are high and effort is increasing in many areas of the world.
Despite the importance of the recreational fishery for striped bass Morone saxatilis along the eastern coast of the United States, little is known about the survival rates of caught and released striped bass. We predicted long-term (58-d) hooking mortality of striped bass after catch and release in saltwater using a logistic regression model. Experimental fishing was conducted on fish (27–57 cm) in a 2-ha saltwater impoundment in Salem, Massachusetts. Depth of hook penetration in the oral cavity, anatomical site of hooking, gear type (treble or single hooks), and angler experience were significantly related to mortality (P < 0.05). The logistic regression model was developed with backwards stepwise selection to predict probability of death from hooking. The final model included depth of hook penetration, gear type, and angler experience as predictor variables. Predicted mortality ranged from 3% under the most favorable conditions to 26% for the worst set of conditions. Predicted as well as observed mortality for the entire experimental group was 9% which is generally much lower than reported in striped bass hooking mortality studies conducted in freshwater. At the end of the experiment, condition factors were significantly lower for surviving hooked fish than for fish that had not been hooked.
https://cran.r-project.org/package=coda
Contains the core survival analysis routines, including definition of Surv objects, Kaplan-Meier and Aalen-Johansen (multi-state) curves, Cox models, and parametric accelerated failure time models.
We studied the effects of catch-and-release angling on rock bass Ambloplites rupestris a small but common centrarchid species in North America. A field study of hooking injury and mortality was conducted in Lake Erie at a water temperature of 16°C. We captured fish using one of four terminal tackle types: barbless worm, barbed worm, barbless jig, and barbed jig. No mortality was observed in any of the four treatments even after holding fish for 5 d. Fish captured using worms were hooked more deeply than fish caught on jigs. Fish captured on barbless jigs were unhooked most easily and more rapidly than with all other tackle types, resulting in an average of only 20 s of air exposure. Because they were more difficult to remove from the hook, fish captured on other terminal tackle experienced at least twice as much air exposure. To assess sublethal effects, we measured the cardiac responses of rock bass exposed to 30 s of simulated angling followed by 30 or 180 s of air exposure. These air exposure durations were intended to simulate the conditions faced by fish that were either easy or difficult to remove from the hook. Fish experienced arrhythmia during angling, although overall cardiac output increased. Fish experienced severe bradycardia during air exposure, but after being returned to the water, all fish exhibited elevated cardiac output. Fish exposed to 30 s of air exposure required 2 h for full recovery, whereas those exposed to 180 s of air required 4 h. During periods of cardiac disturbance, increases in cardiac output were due to both heightened heart rate and stroke volume. Our results suggest that hooking mortality did not vary with bait or hook type and that physiological disturbance of rock bass was influenced by the duration of air exposure, as influenced by bait and hook choice. We recommend that anglers attempt to minimize handling and air exposure of angled fish and keep pliers or other hook removal devices readily accessible to facilitate rapid release of fish not intended for harvest.
When facing small numbers of observations or rare events, political scientists often encounter separation, in which explanatory variables perfectly predict binary events or nonevents. In this situation, maximum likelihood provides implausible estimates and the researcher might want incorporate some form of prior information into the model. The most sophisticated research uses Jeffreys’ invariant prior to stabilize the estimates. While Jeffreys’ prior has the advantage of being automatic, I show that it often provides too much prior information, producing smaller point estimates and narrower confidence intervals than even highly skeptical priors. To help researchers assess the amount of information injected by the prior distribution, I introduce the concept of a partial prior distribution and develop the tools required to compute the partial prior distribution of quantities of interest, estimate the subsequent model, and summarize the results.
Recreational or sports fishing is a multi-billion dollar industry worldwide and in many countries represents an important social and cultural activity. In some regions, it also contributes significant income to tourism and tackle businesses. In addition to its importance from a social and economic standpoint, the impact of recreational fishing on the environment and on food webs can often be substantial. This important book represents the major output from the 4th World Recreational Fishing Conference held in Norway in June 2005. The conference focused on several topics and targeted all stakeholders in the recreational fishing sector, including researchers, managers, NGO representatives and businesses. This book reflects that diversity, encompassing a variety of approaches within its carefully selected and fully peer-reviewed chapters. Global Challenges in Recreational Fisheries is an essential purchase for fisheries managers, multidisciplinary fisheries scientists, marine and freshwater biologists, ecologists and environmental scientists. The book is highly relevant for graduate university courses in fisheries management and fisheries sciences. Libraries in all universities, government fish and wildlife agencies and research establishments where these subjects are studied and taught will need copies of this important publication.
IntroductionWhat are recreational fishing and catch-and-release (C&R)?A brief history of recreational fishing and C&RCatch-and-release as a management toolAttributes of the resource that affect managementFuture trendsConclusions
This is the first study that estimates sea bass recreational catches in the Basque Country including fishers from shore, boat, and spearfishing. Three different offsite survey methods were used (e-mail, phone, and post) and their performance was compared. Estimates were different depending on the survey method used. Total catch estimates for shore fishing were 129, 156, and 351 tonnes for e-mail, phone, and post surveys, respectively. For boat fishing, estimates varied from 5 tonnes (phone) to 13 tonnes (e-mail and post). For spearfishing, only e-mail surveys were performed and total catch was estimated in 13 tonnes. Potential representation and measurement bias of each survey method were analysed. It was concluded that post surveys assured a full coverage of the target population, but showed very low response rates. Telephone surveys presented the highest response rates, but lower coverage of the target population. E-mail surveys had a low coverage and a low response rate, but it was the cheapest method, and allowed the largest sample size. All surveys methods were affected by recall bias. Recommendations are made about how to improve the surveys (increasing coverage, reducing non-response, and recall bias) to set up a routine cost-effective monitoring programme for Basque recreational fisheries. Results show that estimated sea bass recreational catches are comparable to commercial catches, which emphasize the relevance of sampling recreational fishing on a routine basis and including this information into the stock assessment and management processes.
Research on fisheries bycatch and discards frequently involves the assessment of reflex impairment, injury, or blood physiology as means of quantifying vitality and predicting post-release mortality, but exceptionally few studies have used all three metrics concurrently. We conducted an experimental purse seine fishery for Pacific salmon in the Juan de Fuca Strait, with a focus on understanding the relationships between different sublethal indicators and whether mortality could be predicted in coho salmon (Oncorhynchus kisutch) bycatch. We monitored mortality using a ∼24-h net pen experiment (N=118) and acoustic telemetry (N=50), two approaches commonly used to assess bycatch mortality that have rarely been directly compared. Short-term mortality was 21% in the net pen experiment (∼24 h) and estimated at 20% for telemetry-tagged fish (∼48-96 h). Mortality was predicted by injury and reflex impairment, but only in the net pen experiment. Higher reflex impairment was mirrored by perturbations to plasma ions and lactate, supporting the notion that reflex impairment can be used as a proxy for departure from physiological homeostasis. Reflex impairment also significantly correlated with injury scores, while injury scores were significantly correlated with plasma ion concentrations. The higher time-specific mortality rate in the net pen and the fact that reflexes and injury corresponded with mortality in that experiment, but not in the telemetry-tagged fish released into the wild could be explained partly by confinement stress. While holding experiments offer the potential to provide insights into the underlying causes of mortality, chronic confinement stress can complicate the interpretation of patterns and ultimately affect mortality rates. Collectively, these results help refine our understanding of the different sublethal metrics used to assess bycatch and the mechanisms that can lead to mortality.
Markov chain Monte Carlo (MCMC) algorithms are in wide use for fitting complicated statistical models in psychometrics in situations where the traditional estimation techniques are very difficult to apply. One of the stumbling blocks in using an MCMC algorithm is determining the convergence of the algorithm. Because the convergence is not that of a scalar quantity to a point, but that of a distribution to another distribution, the issue remains an enigma to many users of MCMC, especially to those without a sound knowledge of mathematical statistics. This article is an attempt to provide psychometricians using the MCMC algorithms a better understanding of the concept of convergence of the algorithms and an improved knowledge about the diagnostics tools to assess convergence of the MCMC algorithms.
Data collection and estimations of sea bass recreational catches are required by the European data Collection Programme (DCF), and have been included into the ICES stock assessment and advisory process, in order to achieve a global view of the fishing impact on this stock and improve the scientific assessment.
In 2012 a study has been carried out in the Basque Country in order to estimate total sea bass recreational catches in the Basque Country using different survey methods, with a view to setting up a routine cost-effective monitoring program.
A comprehensive list of recreational fishers was obtained with some contact information. The boat census was obtained from a official register and was completed with direct observations and satellite pictures (Google Earth). Catches surveys have been done by telephone, by mail and by e-mail to all types of recreational fishing (including fishing from boat, fishing from coast and spear fishing).
Total seabass captured by recreational fisheries was estimated as a multiplication of an estimated effort, catch rate, and number of people with fishing license. The large amount of zero values of effort and catch rate was taken into account in the calculations.
Sea bass total catch estimations ranged from 148 to 293 tonnes, depending in the type of survey used. Differences were also observed in the standard deviations of the estimations, and in the cost and response ratio of the surveys. Possible bias of each method has to be investigated in order to select the best way to estimate sea bass recreational catches in the Basque Country.
While catch-and-release (C&R) is a well-known practice in several European freshwater recreational fisheries, studies on the magnitude and impact of this practice in European marine recreational fisheries are limited. To provide an overview of the practice and magnitude of C&R among marine recreational anglers in Europe, the existing knowledge of C&R and its potential associated release mortality was collected and summarized. The present study revealed that in several European countries over half of the total recreational catch is released by marine anglers. High release proportions of . 60% were found for Atlantic cod (Gadus morhua), European sea bass (Dicentrarchus labrax), pollack (Pollachius pollachius), and sea trout (Salmo trutta) in at least one of the studied European countries. In the case of the German recreational Baltic Sea cod fishery, release proportions varied considerably between years, presumably tracking a strong year class of undersized fish. Reasons for release varied between countries and species, and included legal restrictions (e.g. minimum landing sizes and daily bag limits) and voluntary C&R. Considering the magnitude of C&R practice among European marine recreational anglers, post-release mortalities of released fish may need to be accounted for in estimated fishing mortalities. However, as the survival rates of European marine species are mostly unknown, there is a need to conduct post-release survival studies and to identify factors affecting post-release survival. Such studies could also assist in develooping species-specific, best-practice guidelines to minimize the impacts of C&R on released marine fish in Europe.
Concerns over the use of minimum-size regulations to increase the average weight of harvested striped bass Morone saxatilis in Tims Ford Reservoir, Tennessee, prompted this study of hooking mortality. To estimate mortality and examine behavior, striped bass longer than 508 mm total length were caught with conventional angling gear, tagged externally with ultrasonic transmitters equipped with floats, and released back into Tims Ford Reservoir. Over a 15-month period 89 fish were tagged and tracked for a minimum of 3 d. Mortality rates ranged from 14% in November and December 1993 to 67% in both August 1993 and July 1994. Although the confounding effects of tagging could not be separated from the effects of being hooked and released, disparate mortality rates among seasons, as well as observations of feeding and swimming behavior of tagged fish that survived, suggested that tagging effects were modest compared to hooking effects. Mortality rates were linearly related to air temperature (P = 0.012) but not to landing time, handling time, bait type, fish total length, or water temperature. Characteristics that differed between striped bass that survived and those that did not were air temperature at capture (t-test; P = 0.007) surface water temperature (t-test; P = 0.081), and handling time (t-test; P = 0.06). Nine striped bass were caught, tagged, and tracked intensively following release in late August 1994 to document their short-term behavior. All six fish that survived remained in warm surface waters for about 2 h following release before descending to the top of metalimnion. The three fish that died, surfaced within 1.5 h, from which we inferred that they were unable to regulate air bladder pressure. We concluded that a proposed year-round size limit of 610 mm total length would probably not improve the size structure of the population because of the high mortality of released fish that occurred during summer months.
Summer and winter hooking mortality rates were estimated for btuegills Lepomis macrochirus caught in June 1989 in Choke Canyon Reservoir, Texas, and in March 1990 in Cedar Lake Reservoir, Texas. Water temperatures averaged 16.7 and 30°C during the winter and summer angling experiments, respectively. Fish were caught by angling with size-4 single-shank hooks baited with live crickets in the summer and earthworms in the winter. Ninety-five fish (109–193 mm total length) were caught in the winter and 75 fish (146–200 mm) in the summer. Fish were held for 72 h in 0.79-m × 1.00-m cylindrical plastic cages to observe delayed mortality. One of 95 fish died in the winter and 19 of 75 fish died in the summer. Hooking mortality was significantly higher in summer than in winter (P < 0.05).
Catch-and-release practices are common in recreational fisheries, yet little is known about the behavior, physiology, and ultimate fate of released fish. We used a combination of radiotelemetry (external attachment) and nonlethal blood sampling (i.e., the blood concentrations of lactate and glucose and plasma concentrations of aspartate aminotransferase (AST), Na, K, and Cl) to assess the relationship between the prerelease physiological status and postrelease behavior and mortality of largemouth bass Micropterus salmoides. The experiments were conducted at two temperatures: approximately 15°C and 21°C. Immediately after capture by standard angling techniques, largemouth bass were exposed to air for 0 to 15 min to assess the consequences of air exposure at two moderate water temperatures. Fish exposed to air for long periods (approximately 10 min or more) had significantly higher concentrations of blood glucose 30 min after air exposure and took significantly longer to regain equilibrium than fish exposed for shorter periods (approximately 3 min or less). The responses of other physiological indicators were inconsistent. Interestingly, at lower water temperatures, males had greater initial concentrations of glucose and AST than females, revealing the importance of sexual differences in the response to angling stress. The fish exposed to air for longer durations tended to exhibit behavioral impairments and remained close to the release site longer than those exposed for short periods. Despite exposure to air for lengthy periods, no postrelease mortality was observed during the 5-d monitoring period. Although the two water temperatures that we used were moderate for this species, a number of sublethal differences (e.g., physiological disturbances and behavioral impairments) were evident in the longer-air-exposure treatment group, highlighting the need to minimize air exposure during catch-and-release angling to maintain the welfare of angled fish.
Although largemouth bass Micropterus salmoides are frequently subjected to sublethal stressors (e.g., angling), the associated effects on their reproductive success have not been assessed. We examined the reproduction of largemouth bass that were subjected to the stress of exhaustive exercise, air exposure, culling, live-well conditions, and weigh-in procedures. Age-0 largemouth bass produced from parents subjected to stress were smaller (total length, 31 ± 0.4 mm (mean ± SE)) and weighed less (0.59 ± 0.04 g) than controls that were not stressed (35 ± 0.4 mm; 0.76 ± 0.03 g). Adults that were stressed had offspring with later swim-up dates than did controls. Our results provide evidence that stress before spawning has the potential to negatively affect largemouth bass reproductive success.
Hypothetical scenarios were used to understand the effects of personal and situational variables on freshwater anglers' choices to keep or release caught fish. When personal and situational variables were included in a single model, the odds of an angler choosing to release a caught fish were negatively related to importance placed on keeping fish and varied according to species preference, species caught, and whether the species caught was the angler's preferred species. Interactions between importance placed on catching a trophy fish and size of fish caught, and between species caught and whether the species caught was the angler's preferred species also influenced catch-and-release choice. Catch-and-release choice was not influenced by experience level, centrality of fishing to the angler's lifestyle, importance placed on number of fish caught, and importance placed on catching "something." Results were not entirely consistent with previous studies, suggesting that determinants of catch-and-release choice may vary across angler populations. Results suggest that both personal and situational variables must be considered for a comprehensive understanding of how anglers arrive at the decision to keep or release caught fish.
Length‐limit regulations and promotion of catch‐and‐release fishing have become increasingly important management approaches for recreational fisheries. We review‐studies on catch‐and‐release (hooking) mortality gathered from the existing fisheries literature and from a survey of fisheries management agencies in all 50 states, the U.S. government, all Canadian provinces, and selected academic and research institutions. We identified hooking mortality estimates for 32 taxa. Most studies dealt with salmonids, centrarchids (especially black basses, Micropterus spp.), and percids (especially walleye, Stizostedion vitreum). Within and among species, differences in percent mortality were reported in association with bait type (artificial vs. natural), hook type (number of hooks, hook size, and barbs), season/ temperature, water depth (depressurization), anatomical location of hook wound, and individual size. Although most hooking mortalities occur within 24 h, the use of initial plus delayed mortality provides a more complete estimate of mortality. Single hooks (especially when used in conjunction with natural baits) resulted in higher mortalities than treble hooks. Environmental conditions (notably high water temperature and low dissolved oxygen) are important to overall mortality related to hooking, playing, and handling. Mortalities were highly variable; occasionally exceeding 30% among red drum (Sciaenops ocellatus), smallmouth bass (M. dolomieu), largemouth bass (M. salmoides), cutthroat trout (Oncorhynchus clarki), and catfishes (Ictaluridae), and 68% among spotted seatrout (Cynoscion nebulosus), bluegills (Lepomis macrocbirus), crappies, (Pomoxis spp.), striped bass (Morqne saxatilis), and coho salmon (O. kisutch). Lake trout (Salvelinus namaycush) and pikes (Esoddae) had mortalities under 15%. The many variables potentially affecting hooking mortality may make optimal management of particular species and water bodies difficult using regional‐level (e.g., statewide) management regulations.