Effects of angling and manual handling on pike behaviour investigated by high‐resolution positional telemetry

Human disturbances such as angling and manual handling may have long‐term effects on the behaviour of pike, Esox lucius L., an ecologically important species. Using continuous high‐resolution positional telemetry, this study compared the swimming activity of handled and unhandled pike in a small lake. Pike pre‐equipped with acoustic transmitters were angled and exposed to a handling protocol including measurements of length and mass. Pike not recaptured constituted an unhandled control group. Results demonstrated that the handling protocol caused temperature‐dependent changes in pike activity, with higher temperatures leading to lower activity of the recaptured pike. The effects, however, were transitory and not detectable after 48‐h post‐release. These findings indicate that pike are relatively resilient to handling and quickly resume pre‐handling activity.     

Depth-based barotrauma severity,reflex impairment and stress response in two species of ice-angled fish

Barotrauma is a frequent event in fish captured from depth, and anglers often attempt to remedy this problem by venting fish. Barotrauma has been frequently assessed in fish during the warm water season, but no work has been done during winter ice angling, and the need and/or effectiveness of venting for ice-angled fish has not been quantified. To answer these questions, bluegill Lepomis macrochirus Rafinesque and black crappie Pomoxis nigromaculatus (Lesueur) were angled through the ice, barotrauma assessed, and the effect of venting on reflex responsiveness and blood glucose levels after 1 or 2.5 h of holding were determined. Greater capture depths resulted in more severe barotrauma, with bluegill experiencing symptoms at shallower depths than black crappie. Bluegill reflex action mortality predictor (RAMP) scores improved more than black crappie scores following venting. These results suggest barotrauma impacts fish in winter fisheries in a similar fashion to fish in warmer conditions, with species-specific differences in their susceptibility to barotrauma and their response to venting.     

Recreational anglers as citizen scientists can provide data to estimate population size of pike,Esox lucius

Catch‐per‐unit‐effort is often used as an approximation of population size. However, for the management and conservation of populations, information about the number of individuals is fundamental. Pike, Esox lucius L., is a popular fish species for recreational anglers. In this study, data in the form of journal keeping by anglers were used: date; place; and photographs of the captured fish; pike were identified based on their natural markings in combination with length measurements. The data were analysed by spatial capture–recapture (SCR) models. Results showed that a small and densely vegetated lake (6.7 ha) in south‐eastern Sweden had a population size of 91 (±22 SE) pike ≥60 cm. On one occasion, 10 individuals were caught, that is 11.1% of the population, highlighting that angling may potentially have a substantial impact on the population size. Hopefully, this study can inspire angler–manager collaborations for conservation of fish stocks.     

Largemouth bass use prior experience,but not information from experienced conspecifics,to avoid capture by anglers

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.     

Voluntary angler logbooks reveal long‐term changes in a lentic pike,Esox lucius,population

Sixty‐two years of voluntarily collected angling logbook data from a large natural Danish lake were used to study variation in pike, Esox lucius L., CPUE (catch per unit effort), expressed as no. of captured pike per boat trip, as an index of stock size. Pike CPUE was positively related to pike release rate by anglers and negatively affected by certain commercial fishers. The stocking of young‐of‐the‐year pike and a fishery‐dependent index of perch, Perca fluviatilis L., abundance (which may be pike prey or predator depending on size) did not correlate with pike CPUE. Analyses of the size distribution of pike, based on sizes of annual record trophy pike captured by anglers, confirmed the negative impact of commercial pike fishing and revealed a positive influence of air temperature. It is concluded that high‐quality angler logbooks that record effort and catch can be a cost‐effective tool to inform lake fisheries management by revealing long‐term population trends. Further, state space modelling, a statistical technique not yet seen in recreational fisheries science, is recommended as a tool to model proxies for population dynamics from angler logbook data.     

Socially induced stress and behavioural inhibition in response to angling exposure in rainbow trout

It is well known that fish can learn to avoid angling gear after experiencing a catch‐and‐release event, that is, after a private hooking experience. However, the possible importance of social information cues and their influence on an individual's vulnerability to angling remains largely unexplored, that is, social experience of a conspecific capture. The effects of private and social experience of hooking on the stress response of fish and subsequent catch rates were examined. Hatchery‐reared rainbow trout, Oncorhynchus mykiss (Walbaum), were implanted with heart rate loggers and experimentally subjected to private or social experience of hooking. Private and social experience of angling induced an increased heart rate in fish compared with naïve control fish. While private experience of hooking explained most of the reduced vulnerability to capture, no clear evidence was found that social experience of hooking affected angling vulnerability in fish that had never been hooked before. While both private and social experiences of angling constitute significant physiological stressors for rainbow trout, only the private experience reduces an individual's vulnerability to angling and in turn affecting population‐level catchability.     

Effects of catch and release angling on Atlantic salmon, Salmo salar L., of the Conne River, Newfoundland

The effects of catch and release angling on survival of Atlantic salmon, Salmo salar L., at Conne River, Newfoundland, were investigated by retaining angled ( n =49; experimental group) and trap-caught ( n =20; control group) fish in holding cages for up to 40 days. Samples were obtained from 8 June to 4 July, 2000, and partitioned among four water temperature strata. Apart from not being angled, control fish were handled, tagged, and transferred to holding cages in a manner similar to angled salmon. Water temperatures and discharge were monitored throughout the duration of the study. Overall, 8.2% of salmon caught and released died, but 12% died among salmon angled in water temperatures ≥ 17.9 °C. No control fish died. There were no significant differences in time associated with angling, exposure to air, tagging, transfer to holding cages, nor total handling time between salmon that survived vs. those that died. Results of the study should encourage managers to continue to use catch and release as a viable tool in the management of Atlantic salmon stocks.     

Fish life history,angler behaviour and optimal management of recreational fisheries

To predict recreational‐fishing impacts on freshwater fish species, it is important to understand the interplay between fish populations, anglers and management actions. We use an integrated bioeconomic model to study the importance of fish life‐history type (LHT) for determining (i) vulnerability to over‐exploitation by diverse angler types (generic, consumptive and trophy anglers), who respond dynamically to fishing‐quality changes; (ii) regulations [i.e., minimum‐size limits (MSLs) and licence densities] that maximize the social welfare of angler populations; and (iii) biological and social conditions resulting under such socially optimal regulations. We examine five prototypical freshwater species: European perch (Perca fluviatilis), brown trout (Salmo trutta), pikeperch (Sander lucioperca), pike (Esox lucius) and bull trout (Salvelinus confluentus). We find that LHT is important for determining the vulnerability of fish populations to overfishing, with pike, pikeperch, and bull trout being more vulnerable than perch and brown trout. Angler type influences the magnitude of fishing impacts, because of differences in fishing practices and angler‐type‐specific effects of LHT on angling effort. Our results indicate that angler types are systematically attracted to particular LHTs. Socially optimal minimum‐size limits generally increase with LHT vulnerability, whereas optimal licence densities are similar across LHTs. Yet, both regulations vary among angler types. Despite this variation, we find that biological sustainability occurs under socially optimal regulations, with one exception. Our results highlight the importance of jointly considering fish diversity, angler diversity and regulations when predicting sustainable management strategies for recreational fisheries. Failure to do so could result in socially suboptimal management and/or fishery collapse.     

Environmental determinants of fish community structure in gravel pit lakes

Gravel pit lakes are increasingly common, and there is an urgent need to better understand the functioning of these artificial and disconnected ecosystems. However, our knowledge of the environmental determinants of fish community structure within these types of lakes remains poor. In this study, we quantified the taxonomic diversity, fish species and life‐stage composition in 17 gravel pit lakes sampled in 2012 and 2013 located in south‐west France to determine the potential role of environmental variables (i.e. lake morphology, productivity, water quality and human‐use intensity) as drivers of fish community structure and composition. Our results demonstrated that fish community structure significantly differed between gravel pit lakes, and we notably found that lakes managed for angling hosted higher levels of taxonomic diversity. We also found that young and large lakes supported higher native species biomass and were dominated by native European perch (Perca fluviatilis). Older, smaller and more productive lakes, located closer to the main urban area, supported a higher biomass of non‐native species such as largemouth bass (Micropterus salmoides). Native and non‐native sport fishing species such as northern pike (Esox lucius), pikeperch (Sander lucioperca), common carp (Cyprinus carpio) and cyprinid prey species were positively associated with fishery management effort, suggesting that management practices play also a critical role in shaping fish species composition. Overall, our study demonstrated that fish community composition followed a predictable shift along environmental gradients associated with the maturation of gravel pit lakes and the associated human practices.     

Impacts of domestication on angling vulnerability of common carp,Cyprinus carpio: the role of learning,foraging behaviour and food preferences

Domestication in fish selection increases vulnerability to angling. Two common garden‐reared genotypes of common carp, Cyprinus carpio L., differing in degree of domestication (highly domesticated mirror carp and less domesticated scaled carp) were exposed to fishing in two environments (i.e. ponds and laboratory tanks) to quantify vulnerability to angling. Foraging behaviour and food preferences were quantified to explain variation in angling vulnerability in a mechanistic manner. Domesticated mirror carp were more vulnerable to angling gear than scaled carp in both environments, which was related to greater food intake and bolder‐foraging behaviour. Independent of genotype, catchability decreased and time until first capture increased over fishing time, indicating learned hook avoidance. No differences were observed in food preferences among genotypes, rendering bait‐selective feeding an unlikely explanation for differential vulnerability to angling. It was concluded that vulnerability to angling has a genetic basis in carp and that boldness plays a paramount role in explaining why more domesticated genotypes are more easily captured by angling.     

Seasonal and diel effects on the activity of northern pike studied by high‐resolution positional telemetry

Abstract – Temperate lakes can be ice covered for several months each year, yet little is known about the behaviour and activity of the fish during the cold season. As northern pike represents the top of the food web in many northern temperate lakes and may structure the ecosystem both directly and indirectly, a detailed understanding of the behaviour of this species during winter is important. We continuously monitored the activity of adult northern pike (Esox lucius) in a small temperate lake from late summer to winter for two consecutive years using an automatic acoustic positional telemetry system. Four subsample periods representing different temperature regimes from each year were chosen for further investigation. The results revealed that pike activity was similar between seasons. In all periods, a distinct diel pattern, showing increased activity during day as compared to night, was evident. Our findings indicate that the fish component of temperate lentic ecosystems can be more active during the cold season than previously assumed. This may have implications for the structuring effect of pike on the lower trophic levels.     

Non‐indigenous fish in protected spaces: Trends in species distribution mediated by illegal stocking

相似文献   

Ice fishing reveals size structure but not abundance of Eurasian perch in small boreal lakes

Management of inland recreational fisheries would benefit from stock abundance and size structure data. Feasibly standardised angling methods such as ice fishing could produce representative catch-per-unit-effort (CPUE) information on the abundance of different-sized fish in small lakes. Here, we first used standard Nordic multimesh gillnets to obtain number-per-unit-effort (NPUE), biomass-per-unit-effort (BPUE) and size structure data on Eurasian perch (Perca fluviatilis) stocks in 11 small boreal lakes in summer. Second, the same lakes were ice-fished by voluntary anglers using a pre-defined, loosely standardised protocol to obtain angling-based NPUE, BPUE, and length frequency distributions. Effects of environmental variables such as water oxygen concentration and light penetration on angling catch rates were controlled statistically. Neither perch Nordic gillnet NPUE nor BPUE corresponded to ice-fishing CPUEs. However, the length distribution of the catch did not differ between methods. Our results imply that traditional ice fishing applying natural baits is relatively unselective for fish size and could produce valid length-based indicators for management purposes while angling CPUE was poorly related to Nordic gillnet CPUE.     

Effects of different angling practices on post-release behaviour of nest-guarding male black bass, Micropterus spp.

Abstract  This study evaluated how different angling practices affect the short-term post-release behaviour of nest-guarding male black bass, Micropterus spp. Male largemouth bass, M. salmoides (Lacepède), and smallmouth bass, M. dolomieu (Lacepède), were angled from their nests and subjected to treatments designed to simulate a variety of common angling practices associated with catch-and-release angling, including fishing tournaments. In addition, some nests had broods reduced (removal of the majority of the eggs or fry from the nest) during the angling treatments to simulate predation of offspring during the angling event. Fish subjected to procedures simulating fishing tournaments (including a 1-h livewell confinement and release 100 m from the nest) exhibited significantly longer rest periods prior to returning to their nest than did other treatment groups. This rest period was longer for largemouth bass than smallmouth bass. Brood removal and air exposure increased abandonment rates compared with controls. These results show that sublethal stressors inherent in some angling practices (such as air exposure and livewell confinement) may delay the return of male black bass to their nest. In the presence of nest predators, the delay in return time could result in increased nest abandonment.     

Effect of catch-and-release angling on growth of largemouth bass, Micropterus salmoides

Catch‐and‐release angling is popular in many parts of the world and plays an increasingly important role in management of recreational fisheries. Although the magnitude of catch‐and‐release mortality is well documented for many species, potential sublethal effects have been little studied. An experiment was conducted to assess directly the effects of catch‐and‐release angling on growth of largemouth bass, Micropterus salmoides Lacépède. Angling mortality was 0.00 ± 0.092% for largemouth bass caught on plastic grubs. There was no difference (P = 0.57) in weight gain between caught and uncaught fish over a 40‐day angling and recovery period. Although catch‐and‐release angling appears to have no effect on largemouth bass growth, previous studies documented sublethal effects on growth and reproduction in other species, suggesting that the occurrence and magnitude of sublethal effects vary among species.     

Effects of air exposure on mortality and growth of undersized pikeperch, Sander lucioperca, at low water temperatures with implications for catch-and-release fishing

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.     

Effects of hook and release on Atlantic salmon in the River Alta, northern Norway

The purpose of the study was to collect information on angling procedures and the effects of hook and release on Atlantic salmon in the River Alta, northern Norway, covering both grilse and multi-sea-winter salmon in a non-artificial setting with real anglers. Information on the angling procedure, handling of the fish and the condition of the fish at release was collected for individual salmon in catch logs (n=543, mean body length 82 cm), whereas physiological stress was studied in a sub-sample (n=15, mean body length 77 cm). To study post-release behaviour, survival and recapture rates, salmon were tagged with radio transmitters (n=30, mean body length 83 cm) and anchor T-tags (n=353, mean body length 79 cm). To evaluate the effects of the hook and release programme on the salmon population, number of spawning redds were recorded from a helicopter in 6 years during 1989–2000.

The results showed that at water temperatures 10.0–14.5 °C, a high proportion of the radio tagged salmon (97%) survived hook and release and stayed in known spawning areas during the spawning period. However, the behaviour after release seemed to be affected by hook and release. Only a small proportion (4%) of the anchor T-tagged salmon was caught more than once within the same season. Increased playing time, increased number of runs during the angling event, hooking in the throat, bleeding at the hook wound, increased handling time, air exposure and water temperature were factors that affected hooked and released Atlantic salmon negatively, either indicated by a poor condition at release, increased stress levels or unnatural behaviour after release. Number of spawning redds were more than doubled after the introduction of compulsory release of all angled salmon in Sautso (the upper 16% of the watershed inhabited by salmon) in 1998, which indicates that hook and release can be an effective management tool to enhance declining Atlantic salmon populations.     

Vegetative substrates used by larval northern pike in Rainy and Kabetogama Lakes,Minnesota

Our objective was to identify characteristics of aquatic vegetative communities used as larval northern pike nursery habitat in Rainy and Kabetogama lakes, glacial shield reservoirs in northern Minnesota. Quatrefoil light traps fished at night were used to sample larval northern pike in 11 potential nursery areas. Larval northern pike were most commonly sampled among floating‐leaf burreed Sparganium fluctuans, common burreed Sparganium eurycarpum, sedges Carex spp., hybrid cattail Typha × glauca and wild rice Zizania palustris. A negative binomial model of light‐trap catches using the presence/absence data for 2012 from all 11 bays included water elevation and the presence of cattail as significant variables. Ultimately, the species of vegetation may not be as important as the physical quality or form of the vegetation in supplying feeding and hiding cover. The aquatic plant species and structural forms encountered by larval northern pike suggest they use nearly any vegetated cover available in early spring. Water‐level regulations that change availability of aquatic vegetation are likely to influence recruitment of northern pike to larger sizes.     

Short-term mortality of Australian bass, Macquaria novemaculeata, after catch-and-release angling

Abstract  Australian bass, Macquaria novemaculeata Steindachner, is angled in large numbers from coastal impoundments and rivers throughout south-eastern Australia. Many are released in the belief that most survive with few negative short-term impacts. This assumption was investigated in three experiments involving a range of conventional angling scenarios. A total of 313 Australian bass were angled and then released along with appropriate controls into either land-based tanks or floating cages, where they were monitored for up to 5 days. No controls died. Short-term mortalities of angled fish were low (0–6%) and attributed to the effects of bait type, hook location and fish size ( P  <   0.05). Specifically, fish that ingested hooks or were caught with natural baits were more likely to die than those that were mouth-hooked or caught on lures. Mortality negatively correlated with fish size. The results supported previous assertions that Australian bass is a resilient, hardy species that should tolerate short-term impacts associated with catch-and-release angling. However, other sublethal physiological impacts that could contribute towards delayed mortalities or reduced reproductive output warrant further investigation, particularly in relation to native populations in coastal rivers that form gauntlet fisheries during their annual spawning season.     

Quantitative estimates of freshwater fish stocking practices by recreational angling clubs in France

Although freshwater fish stocking is widely used by managers, quantitative assessments of stocking practices are lacking in many countries. The general objective of the present study was to determine the quantity and characteristics of fish stocking in metropolitan France. Using a survey-based approach, stocking practices for 2013 by recreational angling clubs in France were quantified, which represented the bulk of fish stocking undertaken in that year. Stocking was found to be practiced by 88.6% of angling clubs in France, representing, on average, 65% of their annual budget. Overall, 22 species were stocked, including 13 native and nine non-native species, with strong variations among species in terms of life stages and body sizes used for stocking. Using Bayesian modelling, a total biomass of 2.029 t, representing approximately 90 million fishes, was estimated to be stocked in France in 2013. In terms of biomass, the most widely stocked species were rainbow trout Oncorhynchus mykiss (Walbaum), brown trout Salmo trutta L., roach Rutilus rutilus (L.), common carp Cyprinus carpio L. and northern pike Esox lucius L. A stocking volume of approximately 60 fishes or 1.5 kg of fish biomass per angler per year seems commonplace in industrialised countries for which data are available.