Article

The impact of catch-and-release on the foraging behaviour of pike (Esox lucius) when released alone or into groups

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Abstract

A commonly practiced method intended to reduce mortality from recreational fisheries is mandatory (e.g., small fish protected by minimum-size limits) or voluntary catch-and-release (C&R), where fish are caught with hook and line and released alive on the assumption that fish survive unharmed. C&R can, however, have both lethal and sub-lethal consequences for fish, with altered behaviour serving as a useful indicator of sub-lethal effects. We here present a mesocosm study on the short-term effects on foraging-behaviour in response to C&R in pike (Esox lucius), when being released alone or into conspecific groups. Due to the potential of cannibalistic attacks or agonistic interactions post-release, we expected that foraging behaviour would be affected by social environment at release. We found that the time to first interest in and attack on prey was significantly delayed in caught and released pike individuals, but these delays were less pronounced in pike released into groups of conspecifics. We also found that the caught and released pike expressed agonistic behaviours in comparable frequencies to unfished group conspecifics. We conclude that the short-term effects of C&R involve altered foraging behaviours, partly depending on the social context at release. Altered feeding, even if only in the short-term, may reduce body growth post-release, which may affect individual fitness and also have effects at the fish community level as a result of changes in pike predation pressure.

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... C&R may also be understood as conservational, assuming that a large proportion of the fish released experience limited fitness consequences (Wydoski 1977;Brownscombe et al. 2017). However, several studies have shown that C&R can negatively impact fish behavior (Suski et al. 2003;Klefoth et al. 2008;Arlinghaus et al. 2009;Halttunen et al. 2010;Gagne et al. 2017;Bower et al. 2019;McLean et al. 2019), physiology (Meka and McCormick 2005;Gagne et al. 2017), feeding responses (Siepker et al. 2006;Stålhammar et al. 2012) and may also result in postrelease mortality (Bartholomew and Bohnsack 2005;St John and Syers 2005;Hühn and Arlinghaus 2011). For example, Bartholomew and Bohnsack (2005) estimated based on meta-analyses of 142 surveys and 132 reports a mean post-release mortality rate of 18%, and the mortality rates were similar among salmonids and marine and freshwater species. ...
... Due to these adverse impacts, most C&R studies focused on sensitive species (Boreman 1997;Gallagher and Klimley 2018;Mann et al. 2018), endangered species (Jensen et al. 2009;Pinder and Raghavan 2013;Cooke et al. 2016) or overfished/highly targeted species (Stålhammar et al. 2012;McArley and Herbert 2014;Ferter et al. 2015;Twardek et al. 2018), and less attention has been given to the impact of C&R on introduced or abundant species, even though they are also highly relevant from an ecological point of view. Additionally, the impact of C&R on these species is particularly relevant because C&R angling is often practiced in protected areas and targets rare/ sensitive species (i.e. ...
... C&R angling is a common practice worldwide, and several studies have shown that C&R can induce deleterious effects and may cause post-release mortality (Suski et al. 2003;Meka and McCormick 2005;Siepker et al. 2006;Klefoth et al. 2008;Arlinghaus et al. 2009;Halttunen et al. 2010;Stålhammar et al. 2012;Gagne et al. 2017;Bower et al. 2019;McLean et al. 2019). Indeed, during C&R, the fish is hooked by its mouth and exposed to air (hypoxia), causing injuries and stress. ...
Article
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Catch-and-Release (C&R) practice may result in post-release mortality in fish. Therefore, most C&R studies have focused on endangered or highly valued target species, and less attention has been given to introduced/abundant species, which indeed are important from an ecological point of view. Nile tilapia is considered an introduced species in many areas and is a commonly caught species in recreational fisheries; therefore, understanding the impacts of C&R on tilapia is also important from an animal welfare perspective. We investigated whether C&R impacts the aggressive behavior and feeding responses of Nile tilapia, characteristics that impair the welfare and the ability of an individual to have success in its ecosystem. Surprisingly, C&R did not affect these responses, and our results suggest that Nile tilapia may be relatively more resilient to C&R, and that C&R practices may act as an additional selective force towards the ecological success of Nile tilapia as introduced species.
... Consequently, angling harvest is likely to have contributed to the pike decline , but i) the very few fishery closures that can be used to assess angling effects, and ii) the use of passive gear ill-suited to sample pike in the national fish monitoring program (Olsson, 2019), have made it difficult to assess the actual causes. Catch-and-release (C&R) is sometimes assumed to be harmless to the fish, but can be a short-term stressor for pike that restricts movement (Arlinghaus et al., 2009) and feeding (Stålhammar et al., 2012), which pike may learn to avoid (Kuparinen et al., 2010). Coastal populations of perch, another large-bodied piscivore which is naturally much more abundant than pike, are declining in some areas and stable or increasing in others (Olsson, 2019). ...
... We therefore hypothesize that the mechanism behind the closure effect on gammarid survival is not simply about numerical relationships, but instead explained by gammarid predators (such as stickleback) being more wary and spending less time foraging, potentially because of a higher risk of being eaten themselves. Stress associated with C&R has been shown to reduce the interest of pike in prey fish and increase attack time, which may affect the prey fish community (Stålhammar et al., 2012). Even though the conditions in that study differed from ours (short-term pond experiment with lower salinity, higher temperature, etc.), this gives support to the hypothesis that the higher survival of tethered amphipods in the spawning closures is a consequence of higher pike interest in, and attack rates on, stickleback as prey fish, in the absence of C&R. ...
... because the motivation may be lowered by the stress from angling experience for not only angling 48 gear but also prey itself [21,22]. Also, aversive experience often enhances the alertness of fish 49 [23]. ...
... For example, the recapture rate of angled fish decreases if 328 fish leave the fishery ground [51]. Stålhammar [22] found that the feeding behavior for a prey of 329 pike was delayed by an angling experience. Meanwhile, angling treatment fish in the present 330 study were not able to go away from the angling gear in the experiment tank, and had the active 331 feeding motivation for prey just before the angling test. ...
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Angling has been the cause of mortality for fish since ancient. The avoidance learning for angling gear could be considered as a survival strategy against the mortality by angling. Whereas some studies indicated the possibility of avoidance learning for angling gear, most studies investigated the avoidance learning by using groups of fish, in which it is difficult to reveal the process and mechanisms of the learning. The present study elucidated the avoidance learning for angling gear by experiment of single fish in a tank using red sea bream Pagrus major juveniles. Individuals with only once or twice of experience for angling avoided angling gear while showing the feeding motivation for pellets, representing avoidance learning for the angling gear. Most of the experienced individuals avoided the krill attached with a fishing line, but not krill and pellets near the angling gear. Feeding rate for prey on a fishing line at two month after the angling trial demonstrated that approximately half of fish kept the memory for angling gear. A series of experiment for angling gear elucidated that red sea bream juveniles are equipped with considerable learning capability for angling gear, suggesting a cognitive evolution for angling.
... For individual pike caught and released multiple times within each angling year (n = 11 in 2020 and n = 12 in 2022), only data from the first capture event was included in the analyses. The reasoning behind this approach is that the first capture event might have altered the shortterm behaviour of the pike following release (Arlinghaus et al., 2017(Arlinghaus et al., , 2009Baktoft et al., 2013;Stålhammar et al., 2012), which could influence how they subsequently strike and ingest the fishing lure/bait. However, data on individual pike caught in both 2020 and 2022 were maintained in the analyses, as we judged that the capture and release events in 2020 would not affect a similar event in 2022. ...
Article
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Catch-and-release (C&R) is a common practice in recreational angling for northern pike (Esox lucius), whereby the angler releases the fish back into the water after capture with the expectation that it will survive with negligible stress and physical injuries. This may not always be the case, as hooking in critical anatomical locations , such as gills, esophagus, and stomach, increases the frequency of bleeding at the hook wound and has been recognized as a key determinant of post-release mortality in pike. Several factors (e.g. bait type and size, hook characteristics, and fish length) can influence the risk of hooking in critical locations, and the fish's willingness to strike the fishing lure/bait may largely depend on previous feeding history and associated motivation to feed. In this respect, food deprivation and greater feeding motivation can be expected to result in an intensified response and more forceful attacks on fishing lures/baits, which could increase the risk of hooking injuries in sensitive tissues, as the fish may ingest the hook more deeply. Here, we assess the hooking location and bleeding occurrence in pike caught on soft plastic shads and baitfish in a shallow eutrophic lake. The prey fish density of this lake, primarily common roach (Rutilus rutilus), has been substantially reduced by seining as part of a lake restoration project. Experimental angling sessions took place at the end of 2020 and 2022, approximately 1-2 months and 25-26 months after the initial reduction in prey fish density, respectively. Removal of roach from the lake was also done regularly by seining after the angling sessions in 2020. Pike angled in 2022 had significantly lower body condition than individuals caught in 2020, indicating that mass removal of roach from the lake resulted in food shortage. The risk of hooking in critical locations (herein defined as hooking in gills and back of mouth) was not associated to angling year, body condition, or length of the pike. However, across the two angling years, the incidence of hooking in critical locations was higher for soft plastic shads compared to baitfish (24.2% versus 7.4%). Pike caught on soft plastic shads also bled more frequently than individuals caught on baitfish (19.7% versus 6.2%), most likely due to the fact that hooking in the gills almost exclusively occurred with soft plastic shads. Bleeding propensity was also not related to angling year, body condition, or fish length. Hence, the present study found no evidence that long-term reductions in food availability and resulting declines in body condition influence how pike strike and ingest fishing lures/baits, at least not in a manner that increases the risk of hooking injuries in sensitive locations. Instead, bait type seems to play the largest role for the observed bleeding patterns. We recommend that future studies investigate the potential effects of C&R angling on the post-release survival of pike with reduced body condition due to limited food availability.
... It must be noted, however, that the current study did not include hooking and handling of the pike that would occur during a failed angling attempt or in catch and release. Catch and release has been found to have effects on growth and habitat use as well as short-term effects on foraging behavior in pike (Klefoth et al. 2011;Stålhammar et al. 2012), but does not appear to have a lasting effect on pike behavior Baktoft et al. 2013;Flink et al. 2021). The current study supports the idea that pike are capable of learning from such events and that such avoidance learning effects occur across predator types. ...
Article
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This study investigated how northern pike with two behavioral strategies in the context of predation interact with natural and artificial baits in simulated angling experiments. Predator types were assessed in three behavioral trials over 15 days by measuring foraging latency under altered conditions (abruptly increased light intensity). Latency revealed fast and slow predator responses showing high individual repeatability, interpreted as proactive and reactive predator types, with reactive individuals adapting their response over time. Both types displayed similar hunting performances in predation trials with live prey under habituated conditions. In angling trials, proactive pike expressed significantly more predation than reactive pike, independent of bait type. During angling trials, predator type did not affect bait handling, while both predator types developed strong sequential bait avoidance, indicating a learning effect. Angling trials did not affect hunting for live prey. The results suggest that pike exhibit individual differences in responses to environmental changes linked to their predatory behavior. Angling selection may play a role in pike populations, with the proactive predator type more likely to be hooked than the reactive type.
... This method results in post-release mortality, physiological stress, potential harm, and other negative effects (Halttunen et al., 2010;Stålhammar et al., 2012;Gagne et al., 2017;Bower et al., 2019;McLean et al., 2019). Additionally, the amount of feed intake may decrease for several days after weighing, resulting in reduced growth rates (Pickering and Christie, 1981;Maule et al., 1989). ...
Article
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Manual measurement of live fish is stressful and may cause injuries or post-release mortality. Therefore, indirect measurement based on image analysis should be developed. In this study, 150 Nile tilapia samples of three different size ranges (0.5–1 g, 20–30 g, and 40–60 g·fish-1) were collected. Each fish was photographed five times from above while freely swimming, and then weighed. Data from 1,500 images (10 images of each fish were analyzed: 5 for whole body and 5 without fins and tail) were manually segmented to extract the view area (V). Based on an 80–20 split test, the data were divided into two sets: training data (120 fish; 1,200 images) and validation data (30 fish; 300 images). The results showed that fish body weight (W) fitted with V without fins and tail achieved a higher coefficient of determination (r2) than whole body. The linear regression model was chosen as the best fit for W estimation based on r2 (0.922–0.958) and several error analyses: root mean square error (RMSE; 1.02±0.86 g), mean absolute error (MAE; 0.90±0.82 g), mean absolute relative error (MARE; 4.57±4.11%), maximum absolute error (MXAE; 1.76±1.36 g), and maximum relative error (MXRE; 0.12±0.10%). Our results indicated that utilizing a linear model was ideal and easy to apply. Furthermore, there is no suffering or weight loss associated with this procedure, since it is not necessary to harvest the fish as with traditional methods. This suggests that the findings of this study can be utilized in a subsequent phase to estimate the weight of freely moving fish, and we also favor incorporating our results with unmanned aerial vehicles (UAVs). Furthermore, Artificial Intelligence (AI) will be employed to identify models capable of autonomous operation.
... Use rods, reels, and line of appropriate strength 3 TA B L E 5 Characteristics and types of best practices advertised by five clusters of local Swedish recreational fisheries management organizations. (Garner et al., 2016;Stålhammar et al., 2012Stålhammar et al., , 2014. Therefore, we encourage further research about human perceptions of different species and their potential ecological consequences, which would also contribute to scholarly discussion about the role of cultural values in management and conservation (e.g., Danley et al., 2021;Langlois et al., 2022;Rypel et al., 2021;Sass & Shaw, 2020). ...
Article
Catch-and-release (C&R) is a popular management tool that can support sustainable development of recreational fisheries, if anglers adopt scientifically informed “best practices.” However, although the role of best practices is widely established in the academic literature, this knowledge is not always disseminated to anglers. In this paper, we investigated if and to what extent local management organizations provided best practice information to anglers. Based on a sample of 331 Swedish organizations, we reviewed the websites through which these organizations sold fishing licenses. Our review demonstrated widespread use of C&R as a management tool yet a general lack of best practice information. Among the small fraction of organizations that mentioned best practices, most mentioned only a single practice, with little consistency among practices that received attention. In addition, best practice information was particularly lacking for pike (Esox Lucius) and perch (Perca fluviatilis), which are by far the most landed and released species nationally. We discovered major knowledge deficiencies that provide insights about where and how to focus efforts for improving best practice information, in the context of local recreational fisheries management.
... Detailed studies on the behaviour of pike have been conducted in aquaria and mesocosms (e.g., Nilsson et al., 2006;Skov and Koed, 2004;Stålhammar et al., 2012) as well as in lakes and rivers using radio telemetry (e.g., Arlinghaus et al., 2009;Jepsen et al., 2001;Kobler et al., 2008aKobler et al., ,b, 2009Koed et al., 2006;Ovidio and Philippart, 2005;Masters et al., 2005), acoustic telemetry (e.g., Laskowski et al., 2016;Monk et al., 2020;Somers et al., 2021) and mark-recapture (e.g., Haugen et al., 2006;Miller et al., 2001;Rosell and Macoscar, 2002). However, pike populations are also present in brackish environments, most notably in the Baltic Sea Wennerström et al., 2017;Winkler, 1987). ...
Article
The northern pike (Esox lucius) has been intensively studied in terms of behaviour due to its relevance to fisheries and its importance for structuring fish communities in freshwater ecosystems. However, little is known about the behaviour of coastal pike living in brackish lagoons. Freshwater ecosystems, particularly lakes and small rivers, are usually finite in space, which can limit the expression of space use as a function of body size and other traits. Better understanding the spatial behaviour shown by coastal pike in extended brackish lagoons and its relationship to body size, sex, season and vulnerability to fishing is an important step to further our knowledge on brackish pike populations and can inform management. Here, we present two years of acoustic telemetry data acquired on a large sample of coastal pike (n = 210) with an extended size range (480 to 1.210 mm total length) inhabiting six interconnected coastal lagoons bordered by the islands of Fischland-Darß-Zingst, Hiddensee, Rügen and Usedom in the Baltic Sea (area ca. 1.200 km²). Overall, the space used by coastal pike (50 % and 95 % utilization distribution, UD) scaled positively with body size, with larger fish using significantly more space after controlling for co-variates, but this effect was mainly observed at the between lagoon level. Within a given lagoon, body size scaling of space use was only observed for the 50 % UD of males. We also found the ratio of 50 % UD on 95 % UD to scale negatively with size, meaning that larger-sized pike used areas out of their core ranges more intensively regardless of sex. Space use also differed between seasons, with activity spaces being elevated in spring likely due to spawning migrations and increased reproduction-related activity. Study design was an important co-variate for our space use proxies, as we collected proportionally more data on pike that used less space, but fish recaptured by fisheries did not differ in space use from those that were not recaptured. All space use proxies were found to be repeatable, suggesting an influence of pike personalities on their individual spatial behaviour. This study provides an updated understanding of spatial behaviour in brackish water-adapted pike and its ties to body size, highlighting how body size in interaction with biotic and abiotic factors drives space use patterns.
... Fish are known to remember threats and maintain aversive behaviors for several days (Davis and Agranoff, 1966;Croy and Hughes, 1991;Brown and Smith, 1998;Brown et al., 2011;Kimber et al., 2014) to several months (Csányi et al., 1989;Zion et al., 2011;Triki and Bshary, 2020). The hooking experience and associated handling (e.g., air exposure) has the potential to induce sub-lethal physiological impairments (Cooke et al., 2013) and may manifest in aversive behaviours, such as locomotor changes (Cooke et al., 2000), altered foraging (Stålhammar et al., 2012), changes in nest side choice and nest site fidelity in nest-guarding species (Twardek et al., 2017) or seeking safer habitats (Klefoth et al., , 2011. However, fish may remember certain negative experiences just for a limited time, with the length of memory scaling with cognitive ability, the degree of noxious stimulation, the severity of the threat (Bintz, 1971;Gallon, 1972;Dunlop et al., 2006) and the rate of environmental change (Kotrschal and Taborsky, 2010). ...
Article
When a fish is caught by angling and released, it is unclear for how long that fish will be able to remember the experience and exhibit hook avoidance. Previous research in ponds using carp (Cyprinus carpio) as a model have suggested that in this species a single hooking event might be enough to cause hook avoidance to last over one year. We re-examined this finding, determining whether private (i.e., personal experience of a catch-and-release event) or social (i.e., sensing a conspecific being hooked and released) hooking experiences maintains hook avoidance 7 and 14 months from the initial experience. A fully controlled laboratory experiment was used that recorded the behavior towards sham-rigs where the hook tip was removed, which served as measure for hook avoidance. Although individuals with a private hooking experience required more time to pick up the sham rig 7 months after the initial hooking relative to controls, no differences in ultimate ingestion rates over a time period of 600 s were found, indicating a more cautious approach to the hook but the loss of hook avoidance after 7 months. For carp with a one-trial social hooking experience, neither an increased latency to ingest the offered sham rig nor differences in ingesting rates compared to never-hooked controls were found, indicating that the carp had forgotten that experience after about half a year. Thus, the previous findings from pond studies with group-held carp according to which one-trial hooking is enough to reduce the capture probability one year after the event could not be replicated in carp tested alone in the laboratory. It is unclear whether strain differences, lack of statistical power or differences in the set up alone or in combination explain the differences in study outcomes.
... Research to date has revealed that modified fish behavior following C&R can include differences in movement (Cooke et al., 2002b;Klefoth et al., 2008Klefoth et al., , 2011, increased susceptibility to predation (Raby et al., 2014(Raby et al., , 2018Lennox et al., 2017), and reduced foraging behavior (Fobert et al., 2009;Stålhammar et al., 2012). However, these studies hold the assumption that behavioral alterations are related to physiological disturbances from the fight, landing, and/or subsequent handling, and not directly from the hook and hooking injuries per se. ...
Article
Recreational catch-and-release angling (C&R) is prevalent and growing in popularity, along with concerns over the welfare of released fish. Although there have been many studies quantifying post-release mortality in fish exposed to C&R, there is growing interest in understanding and minimizing any sublethal consequences of recreational fisheries interactions with the aim of improving fish health and welfare. Short-term fish behavior has been explored as an endpoint for C&R, but effects of hooking injury have not been examined independently of other angling stressors. We used Bluegill (Lepomis macrochirus) as a model to assess whether immediate injuries from hooking or the retention of a hook influenced fish behavior compared to unhooked controls using Z-maze and flight initiation distance tests. Fish that retained a hook were less likely to leave a refuge-emergence chamber than fish that were hooked–unhooked or unhooked controls. Moreover, when fish with the hook retained did leave the refuge, they were less exploratory than fish in the other two treatments. Unhooked control fish and fish that were hooked-unhooked did not significantly differ in their overall behavioral patterns outside the refuge. This suggests that fish are resilient to the acute tissue damage associated with minor hooking injuries and that reported behavioral impairments in fish after release are driven more by hook retention, physiological exhaustion from the fight, landing, and/or subsequent handling and air exposure.
... Some studies have suggested angling gear avoidance learning under large-scale conditions, showing that catch rates in natural conditions and fishponds declined over time through the experience of being captured (Beukema, 1969;Alós et al., 2015). However, these past studies on angling gear avoidance learning were based on large-scale experiments on groups of fish in ponds or large experimental tanks, and were unable to confirm the feeding motivation of each individual fish before they avoided angling gear, implying that the fish might have been demotivated to feed owing to stress from the angling experience (Siepker et al., 2006;Stålhammar et al., 2012), not by angling gear recognition. In addition, in large-scale experiments, naive fish may be misidentified as learned fish owing to group interactions, and vice versa. ...
Article
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.
... For instance, catch-and-release rates in some recreational fisheries in North America and Europe have increased during the last decades, such as in specialized fisheries for Largemouth Bass Micropterus salmoides (Myers et al. 2008), Muskellunge Esox masquinongy (Fayram 2003), Northern Pike Esox lucius (Margenau et al. 2003), and Common Carp Cyprinus carpio (Arlinghaus 2007). Catch and release has sublethal effects on fish (e.g., inducing hooking-related injuries and physiological stress responses; Pankhurst and Dedual 1994;Meka and McCormick 2005), which can lead to behavioral changes in released fish, such as decreased activity (Schreer et al. 2005;Halttunen et al. 2010;Klefoth et al. 2011) and altered feeding (Stålhammar et al. 2012). The experience of being captured and released can also induce hook avoidance learning, which has been documented in as diverse species as Common Carp (Beukema 1970a;Raat 1985;Klefoth et al. 2013), Northern Pike (Beukema 1970b;Arlinghaus et al. 2017aArlinghaus et al. , 2017b, Largemouth Bass (Anderson and Heman 1969;Wegener et al. 2018;Louison et al. 2019b), and Rainbow Trout Oncorhynchus mykiss (Askey et al. 2006;Lovén Wallerius et al. 2019;Koeck et al. 2020). ...
Article
Full-text available
It is essential for fish to respond appropriately when faced with a threatening situation. Accordingly, fish are able to reduce predation risk through learning. In addition to privately learned experiences, fish can acquire social information about a threat by observing the response of conspecifics and use such public information to adapt future behavior through learning. It is unclear if social learning can also influence the behavioral response of fish when faced with human‐induced threats in the form of angling. Using an experimental approach in the laboratory, we examined the influence of private (i.e., direct experience of hooking) and social information on angling vulnerability in Common Carp Cyprinus carpio—a species regularly exposed to catch‐and‐release angling. Compared with control groups, individuals with direct or social experience of catch‐and‐release angling expressed significantly elevated hook avoidance behavior during a short‐term vulnerability assessment hours after a catch‐and‐release experience. In the medium‐term vulnerability assessment, conducted within days after the threat event, fish with direct hooking experience continued to exhibit decreased angling vulnerability, whereas the social experience of catch and release did not consistently reduce angling vulnerability compared with controls. Yet, in a subsequent trial within days after the threat exposure, we found that fish with direct hooking experience and fish with only social hooking experience were both more cautious towards bait (corn) in the presence of a sham rig (i.e., a hookless rig with bait) than when only exposed to bait without a rig. Collectively, these results indicated that the combined influence of direct and social experience of catch‐and‐release angling induced a hook avoidance behavior in Common Carp. The extent to which the phenomenon of social hook avoidance learning exists in other recreationally targeted fish species and in the wild deserves further attention because of the potential to affect catch rates and population‐level catchability.
... Nevertheless, while the sublethal impacts of C&R have been exhaustively studied in some favored model species such as the northern pike (e.g., ARLINGHAUS et al. 2008a;KLEFOTH et al. 2008;2011;STÅLHAMMAR et al. 2012;BAKTOFT et al. 2013;LOUISON et al. 2017b;PULLEN et al. 2017), only one study exists for pikeperch assessing mortality rates and growth impacts of simulated angling on undersized individuals (ARLINGHAUS and HALLERMANN 2007). This attention deficit for pikeperch appears negligent given that observed mortality rates after stress and airexposure were above the average of other species (see mortality rate mentions above; ...
Thesis
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Nest-guarding fish species constitute a sensitive target to disturbances by recreational fisheries during reproduction period. Individuals that are guarding offspring typically show increased aggressiveness, rendering them more susceptible to capture by angling. Although captured nesting individuals are typically released through protective regulations, catch-and-release (C&R) induces an at least temporary cessation of nest-guarding and a stress response in the adult fish. Both increase the potential for enhanced brood predation to occur, with implications for reproductive output. Although pikeperch (Sander lucioperca) is a famous nest-guarding species with high importance for recreational fisheries throughout Europe, the consequences of angling interferences have never been assessed in regard to the reproductive success of nesting individuals. In addition, knowledge about the selectivity of angling for certain phenotypes of pikeperch allows an extension of insights from ecological to potential evolutionary implications of both extractive and non-extractive angling. This study aimed to quantify the impacts of C&R angling on individual reproductive success of pikeperch and the severity of induced behavioral alterations both during and after nest-guarding season. In addition, phenotypic traits of pikeperch that are subjected to both sexual- and angling-induced selection, were identified. Firstly, pikeperch displayed high aggressiveness during nest-guarding, corroborating previously untested assumptions about their increased susceptibility to angling. Angled-and-released males showed unexpectedly long absence times from the nest after catch-and-release, suggesting potentially severe consequences for brood survival. However, the lack of observed nest predation and a low sample size of nesting males left this insight preliminary. Although swimming activity of a majority of pikeperch remained unaffected by C&R during growth season, individuals that were responsive showed prolonged alterations of activity exceeding seven days in all cases. Importantly, while a reduced activity space, possibly relating to territoriality or social dominance, was beneficial to the mating chances of both sexes in pikeperch, this trait tended to be selected against by angling. Conclusions about the impacts of catch-and-release angling on reproductive success of pikeperch remain speculative due to the low statistical power in this study. This is reinforced by the finding that the severities of stress responses induced by C&R may indeed vary substantially across individuals, as was observed with respect to activity during growth season. Thus, in light of the remaining uncertainties, it is recommended to keep catch rates and treatment of captured pikeperch during nest-guarding period at a moderate level. The observations of prolonged nest absence times induced by C&R during spawning and the emerging trend of potential counterselection for space-use between sexual- and angling-induced selection revealed important future research needs that are highlighted in this work.
... . Despite the perception that C&R is an effective management and conservation strategy (Cooke and Schramm, 2007), fishing-related stressors including hooking, exhaustive exercise, handling, and air exposure, can result in physiological disturbances (e.g., measurable changes in cortisol, glucose, lactate, ions, etc.), physical injury, and behavioural impairments that increase the risk of immediate or delayed mortality, or sub-lethal effects with fitness consequences (Brownscombe et al., 2017;Cook et al., 2018). For example, short-term foraging behaviour of pike (Esox lucius) -specifically a delay in interest and attack on prey compared to uncaught controls -has been shown to change following C&R (Stålhammar et al., 2012). A change in feeding habits can affect individual fitness (i.e., reduced growth) and can have broader implications to the fish community (i.e., reduced rates of pike predation). ...
Article
White sturgeon are the largest freshwater fish in North America and are the focus of an intense catch-and-release (C&R) fishery; the effects are largely unknown. We assessed the effect of fight and handling time, water temperature, river discharge rate, and fish size on physiological and reflex impairment responses of wild white sturgeon to angling. Sixty of these fish were tagged with acoustic transmitters to assess survival and post-release behaviour. Survival was high (100%). Water temperature and discharge influenced post-capture blood physiology. Specifically, lactate, chloride, and cortisol concentrations were elevated in individuals fought longer, and captured at higher water temperatures and river discharge. Cortisol was affected by fish size, with lower concentrations found in larger individuals. Only lactate and chloride were positively related to reflex impairment scores. Post-release movements were correlated with physiological state, fight characteristics and the environment. Specifically, higher blood lactate and chloride and those with longer fight times moved shorter distances after release. Contrastingly, higher levels of circulating glucose and potassium, as well as larger fish captured during periods of high discharge moved longer distances. Sturgeon tended to move shorter distances and at slower rates when reflex impairment was high, although reflex impairment scores in general did not explain a significant proportion of the variation of any movement metric. Our results show intriguing variance in the physiological and behavioural response of individual white sturgeon to C&R angling, with some degree of environmental dependence, and highlights the importance of understanding drivers of such variation when managing fisheries.
... With regard to angling, multiple studies have shown that increased density leads to increased vulnerability, for instance in brown trout Salmo trutta L. (Harkonen, Hyvarinen, Paappanen, & Vainikka, 2014) and pikeperch Sander lucioperca (L.) (Raat, 1991). Furthermore, it has been shown that angled northern pike released into groups were quicker to resume normal foraging activities than those released with no conspecifics present, a finding that presumably would leave these pike more vulnerable to subsequent recapture stemming from their social surroundings (Stålhammar, Linderfalk, Brönmark, Arlinghaus, & Nilsson, 2012 This could be due to the accumulated effects of angling, with fish becoming quicker to learn after previous experience with other lures, or it could be related to the lures themselves, as previous work found fish learn to avoid larger, more active lures more quickly (Cole, 2014). ...
Article
Angler satisfaction is based on the presence of catchable fish, and therefore, understanding the mechanisms driving catchability is important for fisheries biologists and managers. Lure avoidance learning (including via social learning) may be a driver of catchability, but these mechanisms have not been explored in depth. To address this, largemouth bass, Micropterus salmoides (Lacépède), were stocked into four ponds, and two were angled using a green plastic worm. Naïve bass were then introduced into all ponds, and angling commenced using a sequence of three lures (green plastic worm, white plastic worm and in‐line spinnerbait). Naive bass stocked alongside experienced conspecifics were not less catchable, indicating socially learned lure avoidance did not take place. Catch rates declined across sessions until the switch to the spinnerbait, when rates temporarily spiked. This suggests that the similarity of a novel lure to previously experienced lures may determine if a fish avoids angling capture.
... Foraging behaviour can be altered by fisheries interactions. Stålhammar et al. (2012) found that pike released from an angling and 60 second air exposure trial had impaired foraging capabilities compared to prior to the trial, however, this effect was dampened when fish were released into arenas containing similar sized conspecifics. These sub-lethal effects are rarely identified (Wilson et al. 2014). ...
Technical Report
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The number of fish that encounter fishing gear is greater than the number of fish retained as catch. The proportion of this difference that die from the encounter is defined as fishing-related incidental mortality (FRIM). FRIM estimates are required for improved stock assessments, but they are difficult to attain and vary across fisheries. To cope with this challenge we review and evaluate the scientific knowledge on FRIM. First, we review the different mortality components of FRIM (i.e., avoidance, escape, depredation, drop-out, on-board, short-term release, and delayed mortality) in relation to how a fish responds to different aspects of a fishery encounter (e.g., handling). To better understand how fish respond to a fishing encounter, different fishing factors (e.g., gear type) that act in consort with extrinsic (e.g., water temperature) and intrinsic (e.g., fish size) factors elicit different fish responses that can lead to the different types of mortality (e.g., acute) were examined. A fish response to a stressor (i.e., factor) is a combination of the magnitude and duration of the stressor itself. The initial fish response includes acute physiological stress and injury, followed by behaviour changes, chronic stress, and increased risk of infection. Next, a review was done to provide an up-to-date accounting of the mortality rate information available on estimates of FRIM for Pacific salmon (Oncorhynchus spp.). We created an interactive and searchable catalogue of evidence from predominantly primary literature using standardized systematic mapping protocols, with a focus on coding information to determine study reliability and relevance. Next, we synthesize the factor and mortality information to provide recommendations on the use of five major mortality risk factors that are linked to FRIM. Each factor (capture, handling, injury, water temperature, and predators) is scaled to a mortality risk to provide guidance on evaluating FRIM estimates. The recommendations from this work are focussed on addressing the current knowledge gaps and examining FRIM in broader physiological and ecological context. Ideas for future work include researching cumulative impacts, sub-lethal effects, drop-off mortality, and predation. We have chosen a fish-centric hybrid approach that focusses first on understanding factors that drive mortality, and then on mortality estimates. As such, this paper is not meant as the definitive guide on FRIM but a transparent, defensible, and rigorous evaluation of the primary evidence base for making future decisions about FRIM. Further guidance on how to use the information herein is part of an accompanying CSAS research document.
... Competition among conspecifics alters the internal state of fish and can increase vulnerability. Stålhammar, Linderfalk, Brönmark, Arlinghaus, and Nilsson (2012) found that releasing captured pike into groups of other pike reduced the latency to reinitiate feeding of the released individual, indicating that competition perceived from social context may initiate risk-taking activity and a faster transition back into the vulnerable state. Pfeiffenberger and Motta (2012) measured the suction feeding velocity of bluegill (Lepomis macrochirus, Centrarchidae) and found that it was influenced by social context, with competition for food inciting greater suction velocities. ...
Article
Considerable time and money are expended in the pursuit of catching fish with hooks (e.g., handlining, angling, longlining, trolling, drumlining) across the recreational, commercial and subsistence fishing sectors. The fish and other aquatic organisms (e.g., squid) that are captured are not a random sample of the population because external (e.g., turbidity) and underlying internal variables (e.g., morphology) contribute to variation in vulnerability to hooks. Vulnerability is the probability of capture for any given fish in a given location at a given time and mechanistically explains the population-level catchability coefficient, which is a fundamental and usually time-varying (i.e., dynamic) variable in fisheries science and stock assessment. The mechanistic drivers of individual vulnerability to capture are thus of interest to fishers by affecting catch rates, but are also of considerable importance to fisheries managers whenever hook-and-line-generated data contribute to stock assessments. In this paper, individual vulnerability to hooks is conceptualized as a dynamic state, in which individual fish switch between vulnerable and invulnerable states as a function of three interdependent key processes: an individual fish's internal state, its encounter with the gear, and the characteristics of the encountered gear. We develop a new conceptual framework of " vulnerability , " summarize the major drivers of fish vulnerability, and conclude that fish vulnerability involves complex processes. To understand vulnerability, a shift to inter-disciplinary research and the integration of ecophysiology, fish ecology, fisheries ecology and human movement ecology, facilitated by new technological developments, is required. K E Y W O R D S angling, catchability, exploitation, fisheries management, longlining, state switching
... However, at unlimited effort, unintended hooking mortality may still undermine sustainability (Coggins et al., 2007), and even if caught fish are released alive at their place of capture and survive, their behaviour and reproductive performance post release can be affected (Cooke et al., 2002;Ostrand et al., 2004;Richard et al., 2013). Documented behavioural effects of C&R include reduced movement (Arlinghaus et al., 2008a;Klefoth et al., 2008Klefoth et al., , 2011 and altered foraging propensity (Siepker et al., 2006;Stålhammar et al., 2012) as well as increased susceptibility to predators (Raby et al., 2013). Behavioural changes can hereby reduce growth rate (Klefoth et al., 2011;Siepker et al., 2006) and ultimately survival (Cooke and Philipp, 2004). ...
... Although it is unlikely that the Chicago sportsmen (see above) affected the abundance of bait fish, such as minnows, more than locally, fishing may indeed affect fish populations. In order to reduce this human impact, Aquat Ecol (2013) 47:125–135 131 catch-and-release (C&R) fishing is now commonly practiced, where caught fish are landed, unhooked and released at the capture location with the aim to cause fish as little harm as possible (Klefoth et al. 2008; Arlinghaus et al. 2009; Stålhammar et al. 2012). Although catch-and-release fishing was probably not practised 125 years ago, recreational fishing is a possible reason behind Forbes' comment on Chicago sportsmen, that is, even then recreational fishing might have affected fish populations. ...
Article
Full-text available
In the present study, we aim at relating Forbes’ remarkable paper on “The lake as a microcosm”, published 125 years ago, to the present status of knowledge in our own research group. Hence, we relate the observations Forbes made to our own microcosm, Lake Krankesjön in southern Sweden, that has been intensively studied by several research groups for more than three decades. Specifically, we focus on the question: Have we made any significant progress or did Forbes and colleagues blaze the trail through the unknown wilderness and we are mainly paving that intellectual road? We conclude that lakes are more isolated than many other biomes, but have, indeed, many extensions, for example, input from the catchment, fishing and fish migration. We also conclude that irrespective of whether lakes should be viewed as microcosms or not, the paper by Forbes has been exceptionally influential and still is, especially since it touches upon almost all aspects of the lake ecosystem, from individual behaviour to food web interactions and environmental issues. Therefore, there is no doubt that even if 125 years have passed, Forbes’ paper still is a source of inspiration and deserves to be read. Hence, although aquatic ecology has made considerable progress over the latest century, Forbes might be viewed as one of the major pioneers and visionary scientists of limnology.
Thesis
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(PL) Zmiany klimatyczne wywierają coraz większy wpływ na globalną, państwową i regionalną gospodarkę, gdyż pośrednio i bezpośrednio oddziałują na tak ważne segmenty, jak produktywność i efektywność rolnictwa czy energetyki, ale również na ochronę środowiska czy bezpieczeństwo ludności. Wpływ zmian klimatu na ekosystemy wodne i zasoby ryb stanowi przedmiot coraz liczniejszych badań naukowych prowadzonych w różnych częściach świata. łagodzenie zmian klimatu i adaptacja do jego zmian to kluczowe wyzwania, jakim musi stawić czoła w XXI w. cała branża rybacka. Gospodarkę rybacką na śródlądziu, w odróżnieniu od rybołówstwa morskiego, można nazwać niskoemisyjną, jednak globalne zmiany na pewno wpłyną i już wpływają na warunki jej prowadzenia. Do wdrożenia właściwych strategii zarządzania i zrównoważonej eksploatacji zasobów rybnych niezbędna jest podstawowa wiedza na temat zarządzanych wód. Gospodarka rybacka jest dość złożoną formą działalności zbudowaną z wielu elementów, takich jak: rybołówstwo komercyjne i rekreacyjne (wędkarstwo) oraz właściwie prowadzona gospodarka zarybieniowa. Gospodarka zarybieniowa musi spełniać trzy podstawowe warunki: musi być ekologicznie dopuszczalna (bezpieczna), a jednocześnie pożądana społecznie i ekonomicznie wykonalna. Efektywna gospodarka zarybieniowa jest kluczowym elementem gospodarki rybackiej, gdyż jednym z jej najważniejszych celów jest utrzymanie lub zwiększenie liczebności populacji cennych gospodarczo gatunków ryb do poziomu, który sprawia, że prowadzenie takiej gospodarki jest opłacalne ekonomicznie. Omawiana dysertacja nie bazuje na skomplikowanych modelach klimatycznych, ale na informacjach uzyskanych od rybackich użytkowników wód, którzy z racji specyfiki swego zawodu są z jednej strony najbliżej środowiska wodnego i jego zmian (a zatem pełnoprawnymi ich obserwatorami), a z drugiej żywotnie zainteresowani powstrzymaniem (jeśli takie występują) negatywnych skutków zmian klimatu na ichtiofaunę i prowadzenie gospodarki rybackiej. Odpowiednie zarządzanie zasobami ichtiofauny, czyli wyważona eksploatacja, zarówno w sposób komercyjny, jak i wędkarski oraz racjonalna gospodarka zarybieniowa, wraz z odbudową środowiska naturalnego, są głównymi zadaniami zrównoważonej gospodarki rybackiej prowadzonej w wodach śródlądowych. Zasadniczym celem prac badawczych składających się na przedmiotową rozprawę doktorską było określenie wpływu zmian klimatycznych i gospodarki zarybieniowej na efektywność gospodarki rybackiej. Prace badawcze podzielono ze względu na poruszoną tematykę. Pierwszy temat, z ogólnym tytułem wpływ zmian klimatycznych na gospodarkę rybacką, analizy przeprowadzono w oparciu o zebrane szczegółowe ankiety, wyplenione przez użytkowników, którzy prowadzą gospodarkę rybacką i wędkarską na jeziorach, oraz użytkowników, którzy prowadzą gospodarkę w zbiornikach zaporowych; w drugim temacie gospodarka zarybieniowa – problematyka odłowu tarlaków, badania przeprowadzono w oparciu o ankiety, które uzyskano od użytkowników rybackich, którzy prowadzą gospodarkę rybacką i wędkarską w jeziorach; w trzecim temacie wielkość i wartość odłowów rybackich oraz zarybień szczupakiem, wykorzystano informacje na temat podstawowych parametrów charakteryzujących analizowane podmioty oraz wielkości i wartości odłowów szczupaka, oraz ilości, rodzaju materiału zarybieniowego i jego wartości, liczby podmiotów zarybiających szczupakiem, wielkości zarybianej powierzchni, całkowitej wartości zarybień wszystkimi gatunkami ryb oraz wielkości i wartości złowionych tarlaków wszystkich gatunków ryb, zebrane przy pomocy kwestionariuszy statystycznych RRW-23 od podmiotów uprawnionych do rybactwa na wodach powierzchniowych płynących (jeziora, cieki, zbiorniki zaporowe); czwarty temat wielkości i wybrane cechy połowów rybackich i wędkarskich szczupaka w perspektywie długoterminowej, opisany został na bazie wieloletnich doświadczeń i badań prowadzonych w Zakładzie Bioekonomiki Rybactwa Instytutu Rybactwa Śródlądowego im. Stanisława Sakowicza; piąty temat ocena efektywności zarybień szczupakiem, podzielony został na dwa podtematy: a) ocena efektywności zarybień szczupakiem w jeziorach, w której analizę oparto na materiałach uzyskanych w Gospodarstwie Jeziorowym Sp. z o.o. w Ełku oraz wynikach badań cen ryb i materiału zarybieniowego, b) ocena efektywności zarybień szczupakiem w zbiornikach zaporowych, gdzie podmiotem uprawnionym do rybactwa w badanych zbiornikach zaporowych jest Okręg PZW w Katowicach. Zbiorniki te były systematycznie zarybiane szczupakiem, i mogły posłużyć jako przykład możliwości przeprowadzenia oceny efektywności zarybień przy wykorzystaniu metod statystycznych oraz informacji o zarejestrowanych przez wędkarzy odłowach i przeprowadzonych zarybieniach. Na podstawie uzyskanych wyników stwierdzono, że uprawnieni do rybactwa w znacznej większości zauważyli w ostatnich latach wpływ zmian klimatycznych na ichtiofaunę i rybackie gospodarowanie; gatunkiem, który według użytkowników rybackich najbardziej narażony jest na zmiany klimatyczne jest szczupak; zmiany klimatyczne najbardziej wpływają na wielkości połowów węgorza; ankietowani najbardziej obawiają się zjawiska dłuższego okresu przebywania kormoranów na akwenach; za najistotniejszy wpływ zmian klimatu na wybrane parametry hydrologiczne jezior respondenci wybrali niskie poziomy i wahania poziomów wód; użytkownicy zbiorników zaporowych uznali, że największy wpływ na populacje ryb nie mają zachodzące zmiany klimatyczne, ale sam zbiornik, który utrudnia migracje ryb; badanych respondentów charakteryzuje wysoka niechęć do potencjalnych zmian i innowacji w kwestii odłowu tarlaków; ilość wylęgu wprowadzana do wód obwodów rybackich w ostatnich latach wykazywała bardzo wyraźną tendencję wzrostową; w skali całego kraju odłowy wędkarskie szczupaka były 8-krotnie wyższe niż rybackie; zastosowanie rachunku korelacji wykazało, że wzrost dawek zarybieniowych szczupaka powodował wyraźne zwiększenie poziomu odłowów, ale po przekroczeniu granicznego poziomu zarybień nie następował wzrost, tylko nieznaczny spadek wydajności; w badaniach efektywności zarybień szczupakiem w jeziorach ełckich nie wykazano statystycznie istotnego związku z zarybieniami, lecz wykazano ekonomizację (dążenie do podnoszenia ekonomiczności) w tym zakresie gospodarowania szczupakiem. Określenie wpływu zmian klimatycznych, ale także gospodarki zarybieniowej na efektywność gospodarki rybackiej nie należy do zadań prostych, gdyż w odróżnieniu od badań laboratoryjnych, gdzie efekty badań widoczne są w stosunkowo krótkim czasie, w przypadku poruszanych w pracy doktorskiej zagadnień na efekty trzeba czekać dość długo. Z tego powodu zdecydowano się skorzystać z wieloletnich obserwacji uprawnionych do rybactwa, których praca zawodowa na tak różnych akwenach trwa czasem dłużej niż 30 lat, i warto podkreślić, jak wartościowe były te informacje. Przeprowadzone w ramach dysertacji doktorskiej badania, wobec znacznej liczby, złożoności i kompleksowego oddziaływania czynników wpływających na prowadzenie gospodarki rybackiej, nie pozwoliły na zidentyfikowanie wszystkich z nich, a tym bardziej na skwantyfikowanie ich wpływu na efektywność tej gospodarki. W związku z tymi ograniczeniami stworzono uproszczony schemat, na którym przedstawiono te z grupy czterech najważniejszych, a nauce znanych, elementów systemu (tj. przyrodniczych, społecznych, ekonomicznych i legislacyjnych), na których wpływ dzięki przeprowadzonym badaniom przynajmniej udało się zidentyfikować i wyrazić w formie pewników bądź wpływów bardzo prawdopodobnych. Wyniki tych badań mogą służyć jako odniesienie do przyszłych norm prowadzenia racjonalnej gospodarki rybackiej na wodach Skarbu Państwa i wprowadzania odpowiednich regulacji prawnych, które bardziej odpowiednio przygotują gospodarstwa rybackie na przyszłe, niestety nieuniknione, zmiany klimatyczne. (EN) Climate change is having an increasing impact on global, national and regional economies, as it directly and indirectly affects such important segments as agricultural or energy productivity and efficiency, but also on environmental protection or human security. The impact of climate change on aquatic ecosystems and fish resources is the subject of increasing scientific research in various parts of the world. Climate change mitigation and adaptation are the key challenges facing the entire fishing sector in the 21st century. Inland, as opposed to marine, fisheries management can be called low-carbon, but global changes will certainly affect and are already affecting the conditions under which it is conducted. Basic understanding of managed waters is required to implement appropriate management strategies and sustainable exploitation of fish resources. As a fisheries sector, fisheries management is a rather complex activity comprising a number of elements, such as commercial and recreational fishing (angling) and properly conducted stocking management. Stocking management must meet three fundamental conditions: it must be ecologically acceptable (safe), and at the same time socially desirable and economically viable. Effective stocking management is a critical component of fisheries management, since one of its most important objectives is to preserve or increase the population of economically valuable fish species to a level that makes such management economically profitable. This dissertation is not based on complex climate models, but on information collected from fisheries managers who, due to the specifics of their profession, are on the one hand closest to the water environment and its changes (and therefore rightful observers), and on the other are vitally interested in halting (if any) negative effects of climate change on fish fauna and fisheries management. Proper management of ichthyofauna resources, i.e. balanced exploitation, both commercially and by anglers, and rational stocking management, together with restoration of the natural environment, are the main objectives of sustainable fisheries management in inland waters. The primary aim of the research work for this dissertation was to determine the impact of climate change and stocking management on fisheries management efficiency. The study was divided according to the subject areas investigated. The first topic, with the general title of the influence of climate change on fisheries management, was analysed on the basis of detailed questionnaires collected from users who run fishing and angling management in lakes and from users who manage in dam reservoirs; the second topic, stocking management – the problem of spawners’ harvest, was based on questionnaires obtained from fishing users who manage fishing and angling in lakes; in the third topic, the volume and value of fishing catches and pike stocking, information was used on basic parameters characterizing the analysed fishing entities and the volume and value of pike catches, data on the quantity, type and value of stocking material, the number of entities stocking pike, the size of the stocked area, the total value of stocking with all fish species and the size and value of harvested spawners of all fish species; these data were collected using statistical questionnaires RRW-23 from entities authorised to fishing on flowing surface waters (lakes, rivers, dam reservoirs); the fourth topic, the size and selected characteristics of pike catches in the long-term perspective, was described on the basis of years of experience and research activities at the Department of Fishery Bioeconomics of The Stanisław Sakowicz Inland Fisheries Institute; the fifth topic, assessment of the effectiveness of pike stocking, was divided into two sub-themes: a) assessment of the effectiveness of pike stocking in lakes, in which the analysis was based on materials obtained from Gospodarstwo Jeziorowe Ltd in Ełk and resultsof studies on prices of fish and stocking material, b) evaluation of effectiveness of pike stocking in dam reservoirs, where the entity authorised to fishing in the investigated dam reservoirs is the Katowice District of Polish Angling Association. These dams were systematically stocked with pike and could serve as an example of how to assess stocking efficiency using statistical methods and information on anglers’ records of catches and stocking events. From the results, it was concluded that: fishery users have overwhelmingly reported the impact of climate change on ichthyofauna and fishery management in recent years; the species most affected by climate change according to fishing users is pike; climate change is having the highest impact on eel catches; respondents are most concerned about the longer residence time of cormorants in water bodies; respondents selected low water levels and fluctuations in water levels as the most important influence of climate change on selected hydrological parameters of lakes; in the opinion of dam users, the greatest impact on fish populations is not caused by climate change, but by the dam itself, which makes fish migration difficult; respondents are strongly averse to potential changes and innovations in the harvesting of spawners; the amount of pike stocking with larvae to the waters of the fishing zones in recent years has shown a very clear upward trend; at the scale of the whole country, anglers’ catches of pike were eightfold higher than commercial ones; application of the correlation calculus showed that an increase in the stocking rate of pike resulted in a clear increase in the level of catches, but when the limit of the stocking rate was exceeded there was no increase, only a slight decrease in the catch efficiency; studies on efficiency of pike stocking in Ełk lakes did not show statistically significant correlation with stocking rates, but showed economization (attempt to increase economy) in this area of pike management. Identifying the impact of climate change and stocking management on the effectiveness of fisheries management is not an easy task, because unlike in the case of laboratory studies, where the effects of research are visible in a relatively short period of time, in contrast to the issues discussed in the dissertation, one has to wait rather long for results. For this reason, it was necessary to make use of the many years of observations of authorised fisheries managers, whose professional work in such various waters sometimes lasted more than 30 years, and it is worth mentioning how valuable this information has been. The studies conducted as part of the dissertation, in the light of the large number, complexity and comprehensive impact of factors influencing fisheries management, did not make it possible to identify all of them, let alone quantify their influence on the effectiveness of fisheries management. In view of these limitations, a simplified diagram was created to present those of the four most important system elements known to science (i.e. natural, social, economic and law) whose impact could at least be identified and described as certainties or very likely. The results of this studies can serve as a reference for future standards of rational fishery management in waters belonging to the State Treasury and the introduction of appropriate legal regulations, which will more adequately prepare fishing entities for future, unfortunately unavoidable upcoming climate changes.
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This study examined and described the basic parameters of the catch-and-release angling of roach Rutilus rutilus and European perch Perca fluviatilis with the mormyshka technique. Catch efficiency, the size of the fish caught, the time required to unhook the fish and the total time during which the fish were handled, hooking location, the occurrence of injury and initial hooking mortality were determined. The study indicates that the mormyshka technique is an effective way to catch roach and European perch when ice fishing. The efficiency of the catches and landings was similar for barbed and barbless hooks. The mormyshka technique also proved to be safe for the fish during catch-and-release fishing. The decided majority of fish were hooked shallowly on the upper jaw, which is a safe location, and injury occurred rarely regardless of the hook type. Generally unhooking the fish from the mormyshka hook was seamless and fish handling was brief. Additionally, when roach were caught with barbless hooks, unhooking time and handling was shorter than it was with barbed hooks. No initial hooking mortality was observed in roach, while it occurred in only two specimens of European perch.
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The aim of the study was to compare the catch efficiency of novice and experienced anglers float fishing with different hook types. The mortality of fish that were caught and released was determined based on the experience of the angler and the type of hook used. The mean catch rates of the experienced angler was 46.7 fish per hour, while that of the novice angler was 33.7 fish per hour. The landing efficiency of fish using hooks with micro-barbs was higher than that with barbless hooks. Angling experience had a significant impact on the mean time required to unhook caught fish and also on the mortality of the fish released. The lowest mortality was noted in fish caught by experienced anglers fishing with barbless hooks. The results of the study suggest that angling experience does not have a great impact on parameters characterizing the quality of angling catches. The efficiency of float fishing performed by novice and experienced anglers was similar. Differences were noted in the time required to unhook the fish and in the mortality of the fish released.
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Zusammenfassung: Die zehn wichtigsten Erkenntnisse und Empfehlungen auf einen Blick 1. Angelfischerei und fachgerecht durchgeführter Fischbesatz vereinen Nutzungund Schutz von Fischen und Gewässern. 2. Fischbesatz ist das zentrale Hegeinstrument der deutschen Angelfischerei und wird dies nach Meinung von Entscheidungsträgern in den Angelvereinen auch künftig bleiben. 3. Organisierte Angler bevorzugen Fischbesatz gegenüber Hegealternativen. Dies führt in vielen Angelvereinen zu einer besatzbefürwortenden Grundstimmung, was zum Festhalten an Besatz als Routinehegemaßnahme beiträgt. 4. Besatz nicht natürlich reproduzierender Fischarten in zum Überleben geeigneten Gewässern ist fischereilich gesehen meistens erfolgreich, während der Besatz von Fischen in reproduzierenden Beständen häufig (unbemerkt) misslingt. 5. Erfolgreicher Besatz stellt unter bestimmten Bedingungen ein ökologisches Risiko für den Erhalt der heimischen biologischen Fischvielfalt dar. Zur Minimierung dieser Risiken sollte Besatz stets mit gesundem Satzfischmaterial durchgeführt werden, das dem jeweiligen Gewässer genetisch nahesteht. 6. In Besatzfragen agieren hierzulande die meisten Angelvereine eigenverantwortlich; eine erfolgreiche Kommunikation von Prinzipien einer guten fachlichen Besatzpraxis muss daher lokal ansetzen. 7. Ausgewählte Wissensgrundlagen der guten fachlichen Besatzpraxis lassen sich über frontal vermittelte Fortbildungsseminare an Gewässerwarte und interessierte Angler vermitteln. Umweltpädagogisch besonders effektiv ist aberdie Verbindung von Theorie und Praxis im Rahmen gemeinsam durchgeführter Besatzexperimente. 8. Lernfähige Hege und Pflege, die jede durchgeführte Hegemaßnahme hinsichtlich ihrer Erfolge evaluiert, kann als Grundprinzip für die anglerische Hege und speziell für das Besatzmanagement empfohlen werden. 9. Einheitsangelfänge (Fänge pro gefischter Zeit) korrespondieren besser als alle sonstigen Maßzahlen mit der Größe der Fischbestände. Entsprechend sollten Einheitsfänge die traditionelle Fischbestandsstatistik, die auf der Gesamtzahl entnommener Fische basiert, ablösen. 10. Nur wenn die Reproduktion stark eingeschränkt ist oder sogar fehlt, ist Fischbesatz die Hegemethode der Wahl. In allen anderen Fällen ist eine Regulierung der Befischung oder die Revitalisierung der Lebensräume erfolgversprechender. Die Höhe der natürlichen Rekrutierung und die damit verbundene Besatznotwendigkeit sollte regelmäßig überprüft werden.
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Angler in Deutschland bevorzugen Raubfische gegenüber Friedfischen (ARLINGHAUS, 2004; ENSINGER,2015) . In diesem Zusammenhang gehört der Hecht (Esox lucius) zu den beliebtesten Fischarten(WOLTER et al., 2003; ARLINGHAUS et al., 2008a;ENSINGER, 2015) . In Berlin und Brandenburg ist der Hecht sogar der Zielfisch Nr. 1 unter den Anglern (ENSINGER, 2015) , die dem pfeilschnellen Räuber meistens mit Naturködern beim Ansitzangeln oder mit Kunstködern beim Spinnfischen nachstellen. Wegen seiner Beliebtheit wird in Anglerkreisen lebhaft diskutiert, was den Fangerfolg beim Hechtangeln maßgeblich beeinflusst. Immer wieder auftretende beliebte Fragen lauten: welcher Köder ist am erfolgreichsten, bei welchem Wetter hat man die besten Fangaussichten oder wo findet man Hechte am ehesten im Gewässer? Der vorliegende Beitrag versucht diese Fragen aus wissenschaftlicher Sicht zu beantworten. Insbesondere um die Bedeutung des Hechtverhaltens für die Fangbarkeit ranken sich viele Mythen und Beobachtungen. Traditionell gilt der Hecht als Lauerräuber, der aus schützender Deckung (z. B. Unterwasserpflanzen,Schilf, Totholz) in seinem Revier (KOBLER et al.,2008a, b) vorbeischwimmende Beutefische attackiert. Unter Fischern und Anglern ist aber auch bekannt, dass sich insbesondere große Hechte regelmäßig im Freiwasser fangen lassen, die in großen nährstoffarmen Klarwasserseen oft als „Maränenhechte“ bezeichnet werden. Telemetrische Untersuchungen von KOBLER et al. (2009) in einem kleinen brandenburgischen Natursee zeigten in der Tat, dass sich einzelne Hechte zum Teilstark in ihrem individuellen Verhalten unterscheiden. Diese Erkenntnis unterstützt die Annahme,dass sich bestimmte Verhaltenstypen (z. B. aktive Schwimmer) besser mit der Angel fangen lassen als ihre (weniger aktiven) Artgenossen bei gleicher Größe und gleichem Alter. Um sich der Frage zur Fangbarkeit von Hechten wissenschaftlich zu nähern, werden im vorliegenden Beitrag aktuelle Studien zusammengefasst, die verschiedene Einflussfaktoren der Fangbarkeit von Hechten beleuchteten. Der Großteil der vorgestellten Studien wurde am Leibniz-Institut für Gewässerökologie und Binnenfischerei in Berlin und in deutschen Naturgewässern angefertigt. Die im Folgenden dokumentierten Ergebnisse bestätigen viele anglerische Praxiserfahrungen aus wissenschaftlicher Sicht, es finden sich aber auch einige Überraschungen.
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Der Hecht (Esox lucius) gehört zu den wichtigsten Zielfischarten der Angler in Deutschland (WOLTERet al. 2003, ARLINGHAUS et al. 2008a). In Berlin und Brandenburg ist er sogar der beliebteste Angelfisch (ENSINGER 2015). Der Hecht lässt sich vergleichsweise einfach angeln (Weithman & Anderson1976). Entsprechend empfindlich reagieren Hechtbestände auf Befischung (MOSINDY etal. 1987, GODDE & COBLE 1991, PIERCE et al. 1995,POST et al. 2002, JOHNSTON et al. 2013). Schon ein äußerst geringer Angelaufwand von nur 1,24 h/ha reichte aus, um ca. 50 % der Jahresproduktion eines kleinen, unproduktiven Sees in Ontario zufangen (MOSINDY et al. 1987). Diverse Gründe erklären die hohe Fangbarkeit von Hechtbeständen im Vergleich mit anderen Fischarten (MOGENSEN etal. 2014). Erstens hat die natürliche Auslese eine hohe Aggressivität bei Hechten hervorgebracht, was zu allem Überfluss mit einer, relativ zu anderen Arten, geringen Lernfähigkeit einhergeht (COBLEet al. 1985). Dadurch wird die Fängigkeit von Hechten vor allem mit Kunstködern begünstigt. Zweitens sind Hechte bis zu einer Länge von ca.55 cm stark an Unterwasserpflanzen und andere Unterstände gebunden (GRIMM 1989; GRIMM &KLINGE 1996). Diese Lebensräume lassen sich von Anglern, z. B. mittels Echoloten oder visuell, leicht identifizieren. Entsprechend wird die gezielte Befischung auch bei geringen Populationsgrößen gefördert (POST et al. 2002). Schließlich ist das Hechtangeln vergleichsweise einfach durchführbar. Das hält insbesondere in kleinen Vereinsgewässern den Angeldruck auf Hecht hoch, auch wenn die Bestände zurückgehen. Obwohl in der Literatur auch von „kollabierenden“ Hechtbeständen (d.h. Reduktionen der Biomasse auf unter 10 % der unbefischten Biomasse oder extrem ausgeprägte Verjüngung) in Reaktion auf anglerische Entnahme berichtet wird (POST et al. 2002), sind solche extremem Zustände selten. Hechte reagieren über diverse Kompensationsmechanismen, z.B. erhöhtes Junghechtaufkommen, reduzierte natürliche Sterblichkeit oder gesteigertes Wachstum (HAUGEN et al. 2007) auf die Bestandsausdünnung, sodass die Gesamthechtbiomasse selbst bei jährlichen Entnahmeraten bis 50 % unverändert hoch bleiben kann, insbesondere wenn große Laichtiere im Bestand verbleiben, die für die ausreichende Reproduktion selbst bei geringen Laicherabundanzen sorgen (TIAINEn et al. 2014).
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The EIFAC Methodologies for assessing socio-economic benefits of European inland recreational fisheries were prepared in 2009 by the European Inland Fisheries Advisory Commission (EIFAC) Ad Hoc Working Party on Socio-Economic Aspects of Inland Fisheries. EIFAC considered that the implementation of fisheries policy and management would benefit from a more compatible, comparable and scientifically rigorous application of benefit evaluation methods. To reach this goal, the Working Party prepared guidelines to conduct surveys focusing on social and economic benefits of inland recreational fishing in EIFAC member countries. Due to institutional aspects and management traditions, these guidelines are confined to Europe. By means of this Occasional Paper, the Working Party tries to highlight both the methodological and practical viewpoints when assessing the monetary value of social net benefits or other societal benefits from recreational fishing. The purpose is to make societal and economic valuation more accessible and to give insight to best current practices and black spots related to these tools.
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Fishing for recreation is a popular activity in many parts of the world and this activity has led to the development of a sector of substantial social and economic value worldwide. The maintenance of this sector depends on the ability of aquatic ecosystems to provide fishery harvest. We are currently witnessing the collapse of many commercial marine fisheries due to over-exploitation. Recreational fisheries are typically viewed as different from commercial fisheries in that they are self-sustaining and not controlled by the social and economic forces of the open market that have driven many commercial fisheries to collapse. Here we reject the view that recreational and commercial fisheries are inherently different and demonstrate several mechanisms that can lead to the collapse of recreational fisheries. Data from four high profile Canadian recreational fisheries show dramatic declines over the last several decades yet these declines have gone largely unnoticed by fishery scientists, managers, and the public. Empirical evidence demonstrates that the predatory behavior of anglers reduces angling quality to levels proportional to distance from population centers. In addition, the behavior of many fish species and the anglers who pursue them, the common management responses to depleted populations, and the ecological responses of disrupted food webs all lead to potential instability in this predator-prey interaction. To prevent widespread collapse of recreational fisheries, fishery scientists and managers must recognize the impact of these processes of collapse and incorporate them into strategies and models of sustainable harvest.
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We reviewed estimates of annual exploitation (u) and total mortality (Z) for populations of largemouth bass Micropterus salmoides and used a simulation model to explore how temporal changes in u have influenced those populations. The review produced 32 estimates of u and 30 of Z spanning 51 years. Fishing mortality was roughly parabolic through time, with a mean of 0.35 for 1976–1989 and a mean of 0.18 for 1990–2003. Thus, average fishing mortality rates have declined by about one-half since about 1990. Total mortality declined with the decline in u, suggesting that changes in u caused lower overall total mortality rates. The evidence further suggests that the decline in u was caused by the voluntary release of fish by anglers rather than by changes in overall fishing effort. The simulation model showed that the decline in exploitation increased adult largemouth bass abundance but reduced the ability of size and bag regulations to improve population metrics owing to low rates of directed harvest. Discard mortality (i.e., the mortality of fish caught and released) would not negate the benefits of lower exploitation unless the mortality of fish caught and released was 0.3 or higher. Changes in angler behavior have substantially reduced fishing mortality for largemouth bass fisheries, which should be considered when developing management plans for this species and others with high rates of voluntary release.
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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 168C. 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 ex- perienced 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. Panfish, including small centrarchids, are com- monly angled and released (Coble 1988), and in some cases represent important recreational fish- eries. These fishes are relatively easy to catch by anglers of all abilities and are frequently landed as both intentional and incidental catches. To date, assessments of angling induced injury, stress, and mortality have been concentrated on more popular game fish species, in particular, salmonids and cen- trarchids of the genus Micropterus(Barnhart 1989; Muoneke and Childress 1994). Rock bass Amblo- plites rupestris are one of the most commonly cap- tured panfish species in the Great Lakes basin of North America (Scott and Crossman 1979; Panek 1981; Storr et al. 1983). This species is generally regarded to be a tenacious and vigorous fighter during angling (Jenkins and Burkhead 1994), al-
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Catch-and-release recreational angling has become very popular as a conservation strategy and as a fisheries management tool for a diverse array of fishes. Implicit in catch-and-release angling strategies is the assumption that fish experience low mortality and minimal sub-lethal effects. Despite the importance of this premise, research on this topic has focused on several popular North American sportfish, with negligible efforts directed towards understanding catch-and-release angling effects on alternative fish species. Here, we summarise the existing literature to develop five general trends that could be adopted for species for which no data are currently available: (1) minimise angling duration, (2) minimise air exposure, (3) avoid angling during extremes in water temperature, (4) use barbless hooks and artificial lures/flies, and (5) refrain from angling fish during the reproductive period. These generalities provide some level of protection to all species, but do have limitations. Therefore, we argue that a goal of conservation science and fisheries management should be the creation of species-specific guidelines for catch-and-release. These guidelines would take into account the inter-specific diversity of fishes and variation in fishing techniques. As recreational angling continues to grow in popularity, expanding to many developing countries, and targeting alternative species, it is important that reasonable data appropriate for specific fish and fisheries are available. The sustainable use and conservation of recreational fishery resources will depend upon the development and dissemination of effective catch-and-release angling strategies based upon sound science to stakeholders around the world.
Article
Full-text available
Management agencies have increasingly relied on size limits, daily bag or trip limits, quotas, and seasonal closures to manage fishing in recreational and commercial fisheries. Another trend is to establish aquatic protected areas, including no-take reserves (NTRs), to promote sustainable fisheries and protect aquatic ecosystems. Some anglers, assuming that no serious harm befalls the fish, advocate allowing catch-and-release (C&R) angling in aquatic protected areas. The ultimate success of these regulations and C&R angling depends on ensuring high release survival rates by minimizing injury and mortality. To evaluate the potential effectiveness of these practices, we review trends in C&R fishing and factors that influence release mortality. Analysis of Marine Recreational Fishery Statistic Survey (MRFSS) data for 1981–1999 showed no statistically significant U.S. trends for total number of anglers (mean 7.7 × 106), total catch in numbers (mean 362 × 106), or total annual catch/angler (mean 42.6 fish). However, mean total annual landings declined 28% (188.5 to 135.7 × 106), mean total catch/angler/trip declined 22.1% (0.95 to 0.74 fish), and mean landings/angler/trip declined 27% (0.42 to 0.31 fish). The total number of recreational releases or discards increased 97.1% (98.0 to 193.2 × 106) and as a proportion of total catch from 34.2% in 1981 to 58.0% in 1999. Evidence indicates that the increased releases and discards are primarily in response to mandatory regulations and to a lesser extent, voluntary releases. Total annual catch and mean annual catch/angler were maintained despite declines in catch per trip because anglers took 30.8% more fishing trips (43.5 to 56.9 × 106), perhaps to compensate for greater use of bag and size limits. We reviewed 53 release mortality studies, doubling the number of estimates since Muoneke and Childress (1994) reviewed catch and release fishing. A meta-analysis of combined data (n=274) showed a skewed distribution of release mortality (median 11%, mean 18%, range 0–95%). Mortality distributions were similar for salmonids, marine, and freshwater species. Mean mortality varied greatly by species and within species, anatomical hooking location was the most important mortality factor. Other significant mortality factors were: use of natural bait, removing hooks from deeply hooked fish, use of J-hooks (vs. circle hooks), deeper depth of capture, warm water temperatures, and extended playing and handling times. Barbed hooks had marginally higher mortality than barbless hooks. Based on numbers of estimates, no statistically significant overall effects were found for fish size, hook size, venting to deflate fish caught at depth, or use of treble vs. single hooks. Catch and release fishing is a growing and an increasingly important activity. The common occurrence of release mortality, however, requires careful evaluation for achieving fishery management goals and in some cases, disturbance, injury, or mortality may conflict with some goals of NTRs. Research is needed to develop better technology and techniques to reduce release mortality, to assess mortality from predation during capture and after release, to determine cumulative mortality from multiple hooking and release events, and to measure sub-lethal effects on behavior, physical condition, growth, and reproduction.
Article
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.
Article
Longer angling durations (capture by hook and line) and higher water temperatures are generally thought to be more detrimental to angled fish. Here, this concept was investigated in smallmouth bass Micropterus dolomieu by monitoring cardiac output (CO) and its components, heart rate (HR) and stroke volume (SV), before, during, and after a simulated angling event in a Blazka-type respirometer. Fish (total n = 31) were acclimated to 12, 16, or 20°C and exposed to conditions that elicited repeated burst swimming either briefly (20 s) or to exhaustion (120–180 s). Resting CO and HR increased significantly with increasing temperature (Q 10 ∼ 2), indicating temperature conformity, whereas SV was not affected by temperature. Recovery times (time after angling until cardiac parameters returned to resting levels) ranged from 0 to 85 min (mean ∼ 40 min) for briefly angled fish and from 20 to 210 min (mean ∼ 105 min) for exhaustively angled fish. These recovery times increased significantly with angling duration but were not affected by water temperature. Almost all of the increase in CO during recovery was attributable to increased HR. At 20°C, the increase in HR was sufficient to result in an increase in CO despite a decrease in SV during the initial portion of recovery. During recovery, both CO and HR increased to approximately 1.8 times and as much as 2.65 times the resting values, whereas SV increased to approximately 1.2 times the resting value. At 20°C, SV typically decreased to 0.8 times the resting value for the initial part of recovery. Recovery intensities (maximum increases in cardiac values) were generally not affected by angling duration. Fish acclimated to 16°C generally had larger recovery intensities than fish at 12°C and 20°C, indicating that for smallmouth bass, 16°C may be an optimal temperature relative to the other two temperatures. From a management perspective, the results suggest that (1) angling duration should be minimized, (2) angling at high as well as low temperatures may be detrimental, and (3) even when fish are angled very quickly, they still undergo a period of increased CO that can last as long as 1 h.
Article
Bonefish (Albula spp.) are a widely distributed group of morphologically indistinguishable marine fish species, that provide a recreational sport fishery, that is important for many local economies. Although the majority of angled bonefish are released following capture, little is known about their behavior or post-release survival. Using ultrasonic transmitters and small visual floats, we assessed behavior and mortality of bonefish following catch-and-release angling at spring water temperatures (25.5-27.3 degreesC) in two regions of the Bahamas with differing shark abundances. All observed mortality occurred within 30 min of release and was a direct result of predation by sharks. In the low shark abundance areas, all released bonefish survived, whereas in the high shark abundance areas, some mortality (39%) was observed. Exhaustively angled fish exposed to air had problems maintaining equilibrium following release. These fish typically spent substantial periods of the first 30 min post-release remaining stationary, then moved in rapid bursts. The results of this study, highlight the benefits of angling and releasing bonefish quickly, minimizing handling and particularly air exposure. Furthermore, when shark predation threat is high, anglers should avoid releasing bonefish in the immediate area. The conservation of exploited recreational bonefish fisheries will depend upon the development and dissemination of science-based catch-and-release strategies.
Book
1. Introduction 2. Estimation 3. Hypothesis testing 4. Graphical exploration of data 5. Correlation and regression 6. Multiple regression and correlation 7. Design and power analysis 8. Comparing groups or treatments - analysis of variance 9. Multifactor analysis of variance 10. Randomized blocks and simple repeated measures: unreplicated two-factor designs 11. Split plot and repeated measures designs: partly nested anovas 12. Analysis of covariance 13. Generalized linear models and logistic regression 14. Analyzing frequencies 15. Introduction to multivariate analyses 16. Multivariate analysis of variance and discriminant analysis 17. Principal components and correspondence analysis 18. Multidimensional scaling and cluster analysis 19. Presentation of results.
Article
We examined the relationship between bait and lure size and type and body size, injury, and handling time for northern pike Esox lucius, an important recreational fisheries resource in much of North America and Europe. Bait type and size were significantly related to the size of fish captured and hooking location. Hooking in critical locations (i.e., gills, gullet) was more likely to occur with natural bait, soft plastic shads and jigs, and spoons than with spinners and wobblers (i.e., plugs). Small baits (
Article
Juvenile pike ( Esox lucius ), a cannibalistic fish species, aggregates within habitat patches. The advantages to cannibals of aggregating in the absence of other predators and food constraints are not immediately obvious. In this study we explore the basis for this grouping by observing how spatial distributions of juvenile pike are mediated by the presence of conspecifics. Solitary pike preferred shallow‐water (0·17 m depth) habitats. When fish density was increased, the average time spent in alternative deep‐water habitat (0·33 m) increased, consistent with a despotic type of distribution and suggesting that interference was occurring. In pairs of fish, one pike, nominally the dominant individual, showed a habitat use similar to that of single fish. The second individual mostly occupied deep water, again consistent with a despotic distribution and apparently mediated by intimidation interference. However, dominant pike did on occasion enter deep water, at which times the subordinate pike remained with the dominant fish, appearing to aggregate in the pool. We propose that habitat‐specific risk could explain aggregations of pike in deep water. Although remaining in close proximity to dominant individuals in deep water would seemingly put subordinate fish at great risk, the alternative of moving to shallow water may increase risk still further by reducing the capacity to perceive and/or evade attacks.
Article
Most research on catch-and-release (C&R) in recreational fishing has been conducted from a disciplinary angle focusing on the biological sciences and the study of hooking mortality after release. This hampers understanding of the complex and multifaceted nature of C&R. In the present synopsis, we develop an integrative perspective on C&R by drawing on historical, philosophical, socio-psychological, biological, and managerial insights and perspectives. Such a perspective is helpful for a variety of reasons, such as 1) improving the science supporting successful fisheries management and conservation, 2) facilitating dialogue between managers, anglers, and other stakeholders, 3) minimizing conflict potentials, and 4) paving the path toward sustainable recreational fisheries management. The present work highlights the array of cultural, institutional, psychological, and biological factors and dimensions involved in C&R. Progress toward successful treatment of C&R might be enhanced by acknowledging the complexity inherent in C&R recreational fishing.
Article
The physiological effects of catch-and-release fishing on largemouth bass Micropterus salmoides from Lake Powell and Mantua Reservoir, Utah, were evaluated, and an estimate of the time needed for recovery from hooking stress was obtained. Fatigue in Lake Powell fish, as indicated by elevated blood lactate, was directly proportional to hooking time (1–5 min) and water temperature, but recovery from the hyperlacticemia was relatively rapid (about 24 h). Hyperglycemia, an indicator of stress hormone production, did not occur in largemouth bass hooked and played for 1–5 min in the coldest water (11–13°C), was moderate in fish hooked and played at l6–20°C, and was severe in fish played for 5 min at 28–30°C. Fish held for recovery in live cages suffered further hyperglycemia, presumably because of the stress of confinement. Ionoregulation, as indicated by relatively stable plasma chloride values, was not immediately affected in largemouth bass caught at water temperatures of 11–13°C or 28–30°C, but an unusual hyperchloremia developed in fish hooked and played at 16–20°C. During recovery, the expected progressive hypochloremia developed. Plasma osmolality was somewhat affected by hooking at all water temperatures tested, but recovery was almost complete within about 8 h. Mantua Reservoir fish were hooked and played only at water temperatures of 23–26°C. The hyperlacticemia and hyperglycemia that occurred were generally more severe than in the Lake Powell fish hooked and played at either 16–20°C or 28–30°C. However, effects on plasma chloride and osmolality were similar to those occurring in Lake Powell fish.
Article
Intraspecific interactions may increase or decrease foraging rates of individual consumers, and such facilitation or interference interactions should affect individual foraging economies as well as predator-prey processes at the population level. To mechanistically predict individual foraging performance, we need to investigate the effects of positive and negative interactions on separate foraging-cycle stages. We illustrate the importance and viability of examining the effects of facilitation and interference on different foraging-cycle stages using three piscivore species as a model system. We studied individual foraging behaviour when alone or in the presence of conspecifics, and show that northern pike foraging in the presence of conspecifics decrease attack frequencies and consumption rates, although no explicit agonistic behaviours were recorded. Pikeperch increase consumption rates in conspecific groups, possibly through a prey-mediated increase in capture success, as pikeperch showed no direct behavioural interactions. The actively cooperating Eurasian perch increase capture success and consumption rates in groups. The results demonstrate the need to combine behavioural studies of positive and negative effects of intraspecific interactions on foraging-cycle stages with quantifications of overall consumption rates. Pure behavioural observations may result in misinterpretations of the effects of interactions on foraging, while studies on consumption rates only would lack the mechanistic base of the obtained results. We also suggest that effects of intraspecific interactions during the foraging cycle should be incorporated in mechanistic models of facilitation and interference to elucidate the link between individual behaviours and higher-order processes.
Article
Tagged pike Esox lucius L. in a drainable pond were fished by hook and line, using either a spinner or a small live fish as bait. Catch per unit effort could be used as a measure for catchability because all captured pike were immediately returned to the pond and mortality was low. Catchability to spinner fishing decreased to very low levels after about half of the population had been caught in this way. Catchability to live bait fishing remained unaffected both by intensive spinner and live bait fishing. It was difficult to capture pike more than once by spinning. In live bait fishing, on the other hand, the number of recaptures closely matched the number expected if catchability remains unaffected by earlier capture. The advantages are discussed of the use of artificial baits over live baits in hook and line fishing for pike.
Article
Angling practice significantly effected the time required for largemouth bass Micropterus salmoides to begin feeding. Mean ±s.e. time until feeding resumed was longest for fish that experienced a simulated tournament (15·6 ± 2·2 h) followed by fish that were caught and released (8·4 ± 2·2 h) and controls (0·3 ± 1·6 h). Effects on feeding related to angling practices were maintained throughout the 48 h observation period. Using multiple logistic regression and bioenergetics simulations, decreased growth in fish subjected to competitive or catch-and-release angling events was predicted. Fish subjected to multiple captures in a pond experiment had greater mass loss than those not captured, supporting model predictions.
Article
Understanding how angling catch rates vary between environments is of interest from ecological and fisheries management perspectives, but this has rarely been investigated in detail. Using experimental catch-and-release angling records for northern pike (Esox lucius) from a small natural lake in Germany and a generalized linear model we investigated how abiotic and fishing-related environmental variables as well as time of day affect pike catch per unit effort (CPUE; fish per hour). Catch rates of pike were significantly increased at low temperatures, high wind speeds and around full and new moon as well as during dusk. Large fishing effort during the past two days reduced catch rates significantly, indicating the combined influence of abiotic and human-induced variables on the catch rates of pike with angling gear. Of all the significant covariates, fishing effort had the most pronounced effect on catch rates. Our results indicate that anglers can increase catch rates by choosing appropriate weather conditions and lunar phases, but that continuously intensive fishing negatively affects future catch rates even in the absence of harvest. This has implications for the choice of sampling effort using angling gear when attempting to assess fish stocks.
Article
We examined the physiological and behavioural consequences of, and recovery from, catch-and-release related stressors using a combined laboratory and field study in northern pike (Esox lucius L.). A laboratory experiment was conducted to investigate the recovery dynamics of physiological indicators of stress resulting from a simulated angling event resulting in exhaustion, with and without additional air exposure of 300 s. In addition, a field study using a combination of physiological and behavioural assessment was conducted to assess the long-term consequences of exhaustive exercise and various air exposure durations. Exhaustive exercise for 60 s led to increased muscle lactate, decreased tissue energy stores, and alterations in plasma ionic status. Recovery from physiological disturbance was rapid with all physiological variables except plasma glucose returning to baseline levels after 6 h. The recovery profile was largely unaffected by air exposure of 300 s that simulated extended de-hooking time. The field component of our study verified the impact of exhaustive exercise on blood lactate values, but did not detect any impact of air exposure varying between 0 s and 300 s on physiological stress indicators. However, pike exposed to air for 300 s were behaviourally impaired in the first hour post-release indicating that despite limited effects on physiological status air exposure resulted in significant impairment of organismal performance. Behavioural patterns returned to normal within several hours. In a three-week post-release monitoring period no mortality occurred. Our results emphasize that angling-induced stressors result in physiological and behavioural disturbances, but that recovery is quick. This suggests that pike are relatively resilient to catch-and-release related stressors but air exposure durations should be kept <300 s to minimize behavioural impairment.
Article
While the impacts of high exploitation on fish populations and aquatic ecosystems are well-documented for commercial fishing, particularly in the marine environment, the potential biological impacts of angling received less attention. This paper discusses angling patterns within a framework of basic ecological and evolutionary literature and examines potential biological impacts of angling by focus-ing on study results associated with high exploitation rates and pronounced selective exploitation. The impacts range from impacts occurring directly on the exploited species (truncation of the natural age and size structure, depensatory mechanisms, loss of ge-netic variability, evolutionary changes), to those that occur on the aquatic ecosystem (changes in trophic cascades, trait-mediated effects). As a third category, impacts re-lated to the angling activity per se are distinguished (habitat modifications, wildlife disturbance, nutrient inputs, loss of fishing gear). Although the main threats to fish often are localized outside recreational fisheries, there is growing evidence that angling and angling associated activities can lead to a decline of fish populations and affect aquatic ecosystems in various ways provided that the degree of the fishing mortality is high and the selective exploitation is intensive. In conclusion, management implications for sustainable recreational fisheries and areas for future research are outlined.
Article
1In models of size-structured predator–prey systems, the effects are evaluated of gape-size limited predation on prey population growth and density when predators are non-interacting, cannibalistic, interfering, and cannibalistic and interfering.2Predation from non-interacting predators markedly reduces prey density, compared with prey densities in the absence of predation. When density-dependent cannibalism between predators is introduced, predator density and therefore total functional response decrease, resulting in a decrease in predation pressure and higher prey densities.3Size- and density-dependent interference between predators substantially decreases functional responses in the predators, and the prey population is thus allowed to grow more dense. Allowing for cannibalism between interfering predators also decreases predator density, but here the decreased number of predators does not have the releasing effect seen in solely cannibalistic predators. The interference between predators decreases with predator density, and per capita functional responses increase and compensate for the decrease in predator density.4These theoretical results are compared with results from natural systems with pikeperch and northern pike. Both species are cannibalistic, and pike are also kleptoparasitic, mirroring the models. Results from introductions of the different piscivores into natural systems corroborate the outcome of the models, since introduction or increased densities of pikeperch have shown to have severe and long-lasting effects on prey, while pike have only initial, decreasing over time effects on prey stock. Thus, predator behaviour may seriously affect predator impact on prey, and size- and density-dependent interactions between predators may be a major key to the understanding of predator–prey dynamics and community composition in lakes.
Article
The composition and abundance of Northern pike (Esox lucius L.) populations in four shallow waters was monitored during a 4–5 year period, using mark-recapture methods. In general, the populations were sampled by using a combination of fishing gear but pike that completed their first growing season (0+ pike) are captured quantitatively by electrofishing (3 kw, DC) exclusively. Within the length range of 0–54 cm fork length, the biomasses of 0+ pike appeared to be negatively correlated with those of larger pike. It is suggested that intraspecific predation is mainly responsible for these relations. The standing stock of <54-cm pike was found to be determined by the amount of aquatic vegetation and more especially so if the different habitat preference of 0+ pike, 0+ < pike < 41 cm and 41 cm ≤ pike < 54 cm was taken into account.
Article
Abstract  The behaviour and survival of pike, Esox lucius L., released with a retained lure in the mouth was studied relative to control fish, which simulated line breakage prior to landing. Behaviour was monitored during the first hour post-release with the aid of visual floats attached to the fish, and longer-term for 3 weeks, by means of externally attached radio transmitters. Lure-treated pike were less mobile during the first hour post-release, but exhibited greater mobility and travelled further distances from the release area in the first 24 h after release than controls. From the second day after release, the behaviour of lure-treated pike was similar to control fish. No mortality occurred in a 3-week monitoring period. These results are indicative of only short-term behavioural impairments resulting from a retained lure and rapid resubmission of normal behaviour after simulated break-offs.
Article
Abstract As undersized fish have to be released after capture in most recreational fisheries, the potential mortality associated with this practice is of interest to managers and anglers. The objective of this study was to assess the effects of air exposure on mortality and growth in pikeperch, Sander lucioperca (L.), <500 mm (total length) at low water temperatures (around 10 °C). Fish were exhaustively exercised by manual chasing for 120 s, exposed to air for 0, 60, 120 or 240 s, and afterwards stocked into two ponds to measure mortality and growth rates. Neither mortality nor growth was statistically significantly different among different durations of air exposure. However, mortality was the lowest in both ponds for fish with no air exposure, which suggested that air exposure adversely affected survival. Mortality was inversely related to length and body mass of pikeperch in one of the two ponds. From a management perspective, it is suggested to avoid air exposure in angled pikeperch that are to be released.
Article
The northern pike (Esox lucius) is a selective and important predator in lake ecosystems. Prey size in pike is limited by pike gape size, which is a linear function of pike body length. Here we show that the absolute gape-size limit in pike is greater than previously considered, and that maximum ingestible prey size is limited by prey body depth. Further, we experimentally show that pike prefer shallow-bodied roach before deeper-bodied common bream, and small prey sizes within each prey species. Handling time in pike increases with prey body depth, and since common bream are deeper-bodied than roach, handling time is longer for bream than for roach of the same length, but equal considering body depth. Prey handling time is suggested to be a major cost to the pike, since it increases the risk of losing the prey, as well as exposure to predation, kleptoparasitism and cannibalism. Consequently, prey vulnerability is determined by risk of predation and intraspecific interactions, and behavioural preferences in the pike, and not by pike gape-size limits. The consequences for natural populations is evaluated by analysing size structures of predator and prey fish populations in a eutrophic lake.
Article
Abstract  This paper summarises recent peer-reviewed literature addressing the effects of catch-and-release angling on black bass, Micropterus spp., to facilitate management and conservation of these fish. Traditionally, the effects of catch and release have been evaluated by measuring mortality. Many recent studies have measured sublethal effects on physiology and behaviour. There is also greater emphasis on adding more realism to sublethal catch-and-release experiments through angler involvement in research activities and by conducting studies in the field rather than in laboratory environments. Owing to these advances, there have been a number of recent findings, which are summarised here, related to air exposure, gear (e.g. circle hooks) and the weigh-in procedure that are particularly relevant to black bass anglers, tournament organisers and fishery managers. Additional research is particularly needed for: (1) population-level effects of angling for nesting fish; (2) population-level effects of tournament-associated mortality; (3) effectiveness of livewell additives for enhancing survival; (4) consequences of fish displacement in competitive events; (5) effects of weigh-in procedures and other organisational issues on fish condition and survival; and (6) reducing barotrauma.
Article
In northern industrialized countries, the inland fisheries sector has long been dominated by recreational fisheries, which normally exploit fish for leisure or subsistence and provide many (poorly investigated) benefits to society. Various factors constrain the development and existence of inland fisheries, such as local user conflicts, low social priority and inadequate research and funding. In many cases, however, degradation of the environment and loss of aquatic habitat are the predominant concerns for the sustainability of inland fisheries. The need for concerted effort to prevent and reduce environmental degradation, as well as conservation of freshwater fish and fisheries as renewable common pool resources or entities in their own right is the greatest challenge facing sustainable development of inland waters. In inland fisheries management, the declining quality of the aquatic environment coupled with long-term inadequate and often inappropriate fisheries management has led to an emphasis on enhancement practices, such as stocking, to mitigate anthropogenic stress. However, this is not always the most appropriate management approach. Therefore, there is an urgent need to alter many traditional inland fisheries management practices and systems to focus on sustainable development.
Article
Abstract The practice of catch and release (CR) as a fisheries management tool to reduce fishing mortality is widely applied in both freshwater and marine fisheries, whether from shifts in angler attitudes related to harvest or from the increasing use of harvest restrictions such as closed seasons or length limits. This approach assumes that for CR fishing policies to benefit the stock, CR will result in much lower mortality than would otherwise occur. There are many challenges in the design of CR studies to assess mortality, and in many practical settings it is difficult to obtain accurate and precise estimates. The focus of this article is on the design and quantitative aspects of estimating CR mortality, the need for a comprehensive approach that explicitly states all components of CR mortality, and the assumptions behind these methods. A general conceptual model for CR mortality that is applicable to containment and tagging-based studies with a slight modification is presented. This article reviews the design and analysis of containment and tagging studies to estimate CR mortality over both the short and long term and then compares these two approaches. Additionally, the potential population-level impacts of CR mortality are discussed. A recurring theme is the difficulty of designing studies to estimate CR mortality comprehensively and the need for additional research into both statistical model development and field study design.
Article
The spatial distribution of individual animals may both cause and be caused by intra- and/or interspecific interactions. This work aims primarily on effects of intraspecific interactions. Agonistic and unequally strong interactions among conspecifics should make the within-population distribution of individuals to be characterised by spatial avoidance of potentially risky conspecifics, according to the individual risks perceived. This process should affect individual performance and involve individual tradeoffs, as failing to adequately avoid risky conspecifics could incur unnecessary costs, while, at the same time, successful conspecific avoidance may reduce access to patches favourable for e.g. foraging or sheltering. Intraspecific agonistic behaviours, such as cannibalism and competition, are likely to have prominent effects in size-structured populations. It is therefore reasonable to assume spatial avoidance of intraspecific risks according to individuals’ size relationships in such populations. With this field investigation I show that individuals of northern pike spatially avoid larger conspecifics. This avoidance creates a size-influenced and spatially clumped distribution pattern among pike individuals. At low pike densities, however, distances between individuals increase, allowing for an even distribution pattern to appear. The spatial distribution patterns among piscivore individuals should affect both the individual performance of predators and the potential for spatial anti-predatory responses of their prey, and hence be a factor in consumer–resource interactions.
Article
Abstract  Because of low fishing mortality that results from catch-and-release angling for carp, Cyprinius carpio L, it is counterintuitive that voluntary catch-and-release (vC&R) of this species induces conflicts within the angling community. Originally motivated by animal welfare concerns, vC&R is today probably as or more strongly criticised within the angling community itself than it is intersectorally. This study reviews the institutional treatment of C&R in Germany and explores within a sociological conflict model the conflicting views surrounding vC&R, specifically in specialised carp angling. It is argued that the intrasectoral (i.e. among angler groups) conflicts around vC&R fishing may divide the recreational angling community, which in turn may weaken the coherence of the entire angling sector. Restricting the opportunity to practice vC&R also can have important social and biological implications, which suggest a rethinking on the current treatment of vC&R recreational angling in Germany.
Article
In the northern hemisphere, pike (Esox lucius Linnaeus) is one of the most important recreational fisheries resources, and regulatory or voluntary catch-and-release angling is common. No information is available about the potential sublethal impacts on pike that catch-and-release fishing may cause, such as behavioural alterations and changes in habitat choice after release. Radio telemetry with N=20 pike was used to test the hypothesis that fish modify behaviour by reducing movement as a reaction to a catch-and-release event in a previously unfished, slightly eutrophic lake, having an area of 25ha and located in northeastern Germany. During a 7-month tracking period, activity of pike was monitored for consecutive 24h every week. Minimum displacement per hour (m) and distance to shore (m) were significantly lower upon the first post release tracking compared to tracking before the capture. Two tracking events after capture, both movement and distance to shore were similar to those measured during pre-angling. There were no significant relations between the change in movement and distance to shore and size of pike. In terms of habitat choice, pike significantly selected for reed and avoided the pelagic area over the whole study period that was not influenced by catch-and-release angling. The results indicated that catch-and-release induces short-term behavioural alterations in pike, probably explained by physiological disturbances and facilitated by evolved anti-predation behaviours. Such alterations, however, seem to be of short duration and reversible suggesting sublethal catch-and-release impacts on pike behaviour are limited.
Article
A brief review is provided in some advances in understanding the ecology of pike Esox lucius Linnaeus over the last 10 years. Based on long-term studies and manipulative, often short-term experiments (laboratory, field and mesocosms) several established theories have been supported, as well as new concepts developed. Despite their wide distribution pike show low levels of polymorphism and divergence indicative of a recent common ancestral population. Recent genetic studies, however, indicate a single refugium in North America compared to several refugia in Europe. Pike are found in rivers, lakes and weakly saline waters. Variables such as growth and mortality are mainly affected by factors such as temperature, water transparency, productivity, availability of prey and density of pike and other predators. In choice of habitat pike have been shown to support the ideal free-distribution theory. The importance of macrophyte habitat in the life history of pike has been reconfirmed and pike have been shown to be flexible in response to water clarity. Pike are extremely ‘plastic’ in choice of prey types, prey size and in response to prey behaviour (e.g. they are unaffected by shoal size). Predation by pike not only affects abundance and biomass of prey (including younger and smaller pike through cannibalism which plays a major role in population dynamics, other fishes and invertebrates) but also evolution and adaptation of their morphology (in particular body shape) and behaviours. There appears to be no relationship between stock and recruitment. Recruitment is influenced by several abiotic factors in lakes and rivers. Pike play a major role in structuring freshwater communities and have been used in stocking programmes to improve water quality (biomanipulation). Many new concepts have been developed in pike behaviour in maximizing these stocking programmes both in biomanipulation and fisheries management. Despite many recent advances in understanding the ecology of pike, particularly at the individual level, developments in quantifying and modelling the role of pike as a top predator in large ecosystems have been limited, probably due to the difficulties of sampling natural populations.