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Can smartphones kill Trout? Mortality of memorable-sized Bull Trout (Salvelinus confluentus) after photo-releases
Abstract
Mortality associated with catch-and-release (C&R) fisheries is typically estimated as a single value associated with fish that are immediately released after capture. However, with the widespread use of smartphones by anglers, memorable or rare fish may be subjected to prolonged handling time for photographs and measurements, resulting in increased air exposure and subsequent increased potential for post-release mortality. In situations of overfishing, large fish become rarer and their memorable status may increase. This may create a depensatory cycle of additional handling and mortality. The combination of mortality from prolonged handling, immediate release, and illegal harvest is a cumulative C&R-related cryptic mortality that may have population level effects in high-effort sport fisheries. We investigated the potential post-release mortality of memorable sized (average length of 60 cm) bull trout after simulating prolonged handling (involving photographing and measuring) and immediate release in a controlled angling study at a remote Albertan lake during summer. We found that handling time and air exposure of large bull trout subjected to photography and measurement was long (112 s) and associated post-release mortality was high (10 dead / 30 fish; 33 % after 24 h observation). Immediate release mortality was also high (3 dead / 20 fish; 15 %). These levels of mortality, combined with high angler effort, can potentially lead to population-scale declines at C&R fisheries. The complexity and difficulty of population-scale and field-level measurements of cryptic mortality suggest that adaptive management experiments in reductions in angling effort and improved fish handling may be effective in increasing understanding of sustainable angling.
... Salmonid fishes are an important target of recreational fishers around the world, and the effects of C&R on salmonids has been the focus of extensive research in lake and lotic environments, particularly anadromous species making spawning migrations Joubert et al., 2020;Kerr et al., 2017;Lennox et al., 2015). In contrast, relatively few studies on C&R have looked at the biophysical responses of anadromous salmonids caught in coastal waters (Whitlock et al., 2016). ...
... Air exposure after extended fight times has been shown to increase mortality in O. mykiss and has been demonstrated to be a component of delayed mortality in bull trout Salvelinus confluentus (Suckley 1859) (Ferguson & Tufts, 1992;Joubert et al., 2020). It has also been shown to increase sublethal behavioural impacts in S. salar, measured as downstream movement after release (Thorstad et al., 2003). ...
This study investigated the biophysical responses of sea run brown trout Salmo trutta to catch‐and‐release in the coastal fishery around Gotland, Sweden. It used information recorded on individual angled S. trutta (n = 162) including fight time, handling time, total air exposure time, injury, bleeding, fish length, body condition, spawning status, water temperature, hook location and difficulty of hook removal. Reflex action mortality predictors (equilibrium, operculum beats, tail grab response, body flex response, and vestibular‐ocular response), tests of blood glucose and lactate, and observation of hooking injury to measure the relative impact of the angling event on the fish's physical state and stress experienced. The results of this study suggest low rates of post release mortality and generally limited stress responses to angling events, and relatively high post release survival supported by the recapture of many tagged S. trutta. However, a number of scenarios were identified in which stress responses are likely to be compounded, and where anglers should take additional action to reduce sub‐lethal physiological disturbances and the risk of delayed mortality. Particular care should be taken to limit cumulative total air exposure to <10 s, reduce handling time, and risk of additional injury in angling events with extended fight times, when water temperatures >10 °C, or where S. trutta show evidence of being physically compromised by injury or having recently spawned. The results also indicate the importance of using appropriately sized single hooks, rather than larger treble hooks to reduce hooking injury and handling time during unhooking. This article is protected by copyright. All rights reserved.
... This is reflected in the relationship between respondents favouring release of sea trout and a greater likelihood of them photographing the catch. However, taking a photo has the potential to negatively influence the success of the release through increased handling time and possibly increased air exposure if best practices are not followed (Cook et al., 2015;Joubert et al., 2020). Awareness of possible unintended negative impacts from photographing catches may be another important knowledge gap in this fishery, particularly for anglers that always or often photograph their catches of sea trout. ...
The wide variety of perspectives and actions of individual anglers contribute greatly to success or failure when adopting and implementing fisheries management tools. Catch-and-release (C&R) is one such tool where success is influenced by both variation in human factors, but also species and fishery specific characteristics. In this study, an intercept survey of 94 sea trout anglers in a C&R dominated fishery on the Swedish island of Gotland investigated motivations to release or retain catches, self-assessment of anglers' own ability to release fish, and their rating of the importance of various factors influencing the successful outcomes of C&R. Retention of catches was most strongly motivated by situations where anglers deemed the fish unlikely to survive, however more than half of anglers acknowledged being unaware of delayed mortality in released fish. The spawning status of an individual fish was the primary motivation for release, particularly among anglers that prefer to keep at least some of their catches. The roles of water temperature, using single, and barbless hooks were scored as significantly less important than other components contributing to the success of a release. Anglers that gave a favourable rating to their ability to release sea trout also gave greater importance to various factors influencing the success of release, reported higher catch per unit effort, and released a greater proportion of their catches. These findings are discussed in the context of bridging knowledge and behavioural gaps around best practices for C&R in this fishery.
... PDF p. 32: Under incidental harvest, note that post-release angling mortality can reach 33% from excessive handling and delayed release of large fish (Joubert et al. 2020). Also, it is claimed that scientific sampling is a low-risk threat. ...
Mayhood, D. W. 2020. Comments on the proposed recovery strategy for the bull trout, Saskatchewan River drainage populations. Report prepared on behalf of Timberwolf Wilderness Society, Pincher Creek, Alberta, for Species At Risk Directorate, Department of Fisheries Oceans and the Coast Guard Ottawa, Ontario, iii+23 p. FWR Technical Note No. 2020/07-1 doi:10.13140/RG.2.2.28345.60008
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Canada’s Minister of Fisheries, Oceans and the Coast Guard released a proposed recovery strategy under the Species At Risk Act (SARA) for the designated unit (DU) of Bull Trout (Salvelinus confluentus), Saskatchewan-Nelson rivers populations, in Canada on 1 June 2020. Comments on the document were solicited from the public.
Here I comment on this document on behalf of Timberwolf Wilderness Society and FWR Freshwater Research Limited. The comments focus on
• to what extent the document meets the requirements of the Species At Risk Act (SARA), and
• to what extent the proposals constitute good conservation science that could be expected to
recover the species sufficiently so that it reasonably could be delisted.
In brief, I make the following main points.
• The stated goal does not provide a quantitative target against which progress can be measured, and which can be used to determine objectively when the program has been successful. I make several suggestions about how to correct this problem.
• The definition of residence is limited to only the redd, so does not meet the specifications of SARA section 1(2), which describes residence as “including breeding, rearing, staging, wintering, feeding or hibernating.” Biologically, the lake or stream occupied by the Bull Trout population is its residence.
• The definition(s) of critical habitat are internally contradictory, which will make management difficult and enforcement of SARA protections next to impossible. The entire stream used by the fish at some point in its life history is critical habitat, not just (as described in this document) a few specific, carefully limited features, and not just when those features are used by Bull Trout at carefully limited times. This is the biological reality, and it needs to be stated clearly as the unequivocal definition of instream critical habitat in this recovery strategy.
The document correctly recognizes critical habitat as extending into the terrestrial realm, but only to a highly limited degree: a 30-m wide riparian “buffer” strip on either side of those parts of the channel with the very specific, limited “functions, features, and attributes” identified as inchannel critical habitat. In reality, the watershed as a whole is the true terrestrial portion of critical habitat, and needs to be clearly defined as such in this recovery strategy.
The proposed recovery strategy identifies where critical habitat may be found as extending upstream in the entire watercourse network to the watershed boundary, but again, only to a highly limited degree. In reality, critical habitat includes the entire watercourse network draining to those parts of that network used by Bull Trout during some part of their life history.
• Action plan. Eight years after Bull Trout were formally identified as threatened by the Committee on the Status of Endangered Wildlife in Canada, this recovery strategy proposes to leave an action plan describing in detail the specific actions that will be taken to actually begin recovering Bull Trout populations, for up to five years more. This Bull Trout DU is projected to decline by a further ≥ 30% over the next three generations as of 2012, so it has declined a further 10% by now. This recovery strategy intends to allow the DU to decline by yet another 5% before acting.
• The Fish Sustainability Index (FSI) assessments for individual watersheds lack any evidence supporting them. The problem can be rectified by posting technical reports with the supporting data and analyses on the SARA registry.
• The recovery strategy is designed to work around continued multiple land-uses sanctioned by the Government of Alberta. It is seriously unrealistic to expect to recover already at-risk species, such as threatened Bull Trout, while the lands and waters needed for recovery are subjected to ever-increasing (ab)use from industry, urbanization, grazing, and recreation. The total intensity of land-uses is about to increase by orders of magnitude as the Government of Alberta closes parks, opens most of the Bull Trout critical habitat watersheds to strip mining of coal, and encourages a 30% increase in timber exploitation by 2030. To retain any credibility at all, some recognition of these overwhelming threats to the success of Bull Trout recovery must be acknowledged in the final version of the recovery strategy.
Tässä julkaisussa käsitellään kalastajien suhtautumista kalastuksen säätelyyn ja ohjaustoimenpiteisiin, taimenkannan alkuperäisyyden merkitykseen sekä Oulangan villin taimenen kalastukseen. Aineistona käytetään Oulanka-, Kitka- ja Kuusinkijokien kalastajille kesällä 2020 tehdyn kyselyn tuloksia. Kysely toteutettiin elektronisesti Webropol-alustalla, ja aineiston keruuaikana 1.7.2020-31.9.2020 kyselyyn vastasi yhteensä 376 kalastajaa. Kyselylomaketta jaettiin niin kalastajien internet-foorumeilla kuin sosiaalisen median eri alustoilla.
Kyselyn laatimisessa tehtiin yhteistyötä Metsähallituksen Eräpalveluiden kanssa. Tutkimuksen pohjana oli Itä-Suomen yliopistossa tehtävä ympäristöpolitiikan väitöskirja, jossa tutkitaan kestävää virkistyskalastusta, kalastuksen säätelyä sekä kalastajien suhtautumista erilaisiin säätelytoimiin ja pyynnin kohteena oleviin kalakantoihin. Kyselyä suunniteltiin siten, että siitä saatavia tuloksia pystytään hyödyntämään myös Metsähallituksen Eräpalveluiden johtamassa Karelia CBC -ohjelman Pro Trout -projektissa.
Saatujen tulosten perusteella kalastajat suhtautuvat keskimäärin myötämielisesti nykyistä tarkempaan kalastuksen säätelyyn Oulanka-, Kitka- ja Kuusinkijoella. Aineisto osoittaa, että kalastajien keskuudessa on hyväksyntää sekä koukkujen väkäsrajoituksille että käytettävien koukkujen määrän rajoittamiselle. Kalastuksen järjestävien tahojen on syytä huomioida erilaisten ohjaustoimien mahdollisuus, joilla kalastuskuolleisuutta voidaan laskea ja siten edistää vapautettavien kalojen hyvinvointia. Muun muassa kalastuksen rajoittaminen liian lämpimän veden aikaan sekä vapautettavien kalojen ilma-altistuksen vähentäminen näyttäytyvät toivottuina toimenpiteinä.
Pyydettävien kalakantojen osalta aineisto oli yhteneväinen sen osalta, että harjus oli tärkein ravinnoksi pyydettävä kalalaji. Tulos on huomionarvoinen etenkin harjuksen pyyntimitan ja kiintiöiden seurannan tarvetta ajatellen. Vastaavasti alkuperäinen, Oulangan villi taimen näyttäytyy merkityksellisimpänä elämyksellisen pyynnin kohteena. Aineiston perusteella voidaan todeta, että mikäli villi taimen menetetään Kuusamon joista, alueiden kalastuksellinen vetovoima laskee. Tulosten perusteella villin, luontaisesti lisääntyvän taimenen menettämisestä aiheutuvaa haittaa ei voida kompensoida täysin istuttamalla uusia taimenia tilalle, vaan luontaisesti lisääntyvän ja alkuperäisen taimenen pyynti on kalastajille palkitsevinta.
Alkuperäinen julkaisu / Original publication: https://julkaisut.metsa.fi/assets/pdf/lp/Asarja/a235.pdf
Technology that is developed for or adopted by the recreational fisheries sector (e.g., anglers and the recreational fishing industry) has led to rapid and dramatic changes in how recreational anglers interact with fisheries resources. From improvements in finding and catching fish to emulating their natural prey and accessing previously inaccessible waters, to anglers sharing their exploits with others, technology is completely changing all aspects of recreational fishing. These innovations would superficially be viewed as positive from the perspective of the angler (aside from the financial cost of purchasing some technologies), yet for the fisheries manager and policy maker, technology may create unintended challenges that lead to reactionary or even ill-defined approaches as they attempt to keep up with these changes. The goal of this paper is to consider how innovations in recreational fishing are changing the way that anglers interact with fish, and thus how recreational fisheries management is undertaken. We use a combination of structured reviews and expert analyses combined with descriptive case studies to highlight the many ways that technology is influencing recreational fishing practice, and, relatedly, what it means for changing how fisheries and/or these technologies need to be managed—from changes in fish capture, to fish handling, to how anglers share information with each other and with managers. Given that technology is continually evolving, we hope that the examples provided here lead to more and better monitoring of technological innovations and engagement by the management and policy authorities with the recreational fishing sector. Doing so will ensure that management actions related to emerging and evolving recreational fishing technology are more proactive than reactive.
Westslope cutthroat trout currently occupies no more than 20% of its historical distribution in Alberta. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has designated the species as ‘Threatened’. In the Upper Oldman River drainage, cutthroat trout still occupies most of its historical range; however, detailed information on the current status of the population is insufficient for fisheries management. We conducted a basin‐wide stock assessment to facilitate collection of a rigorous database and to evaluate the need for a catch‐and‐release fishery. We divided the drainage into four strata based on stream size and electrofished a total of 126 stream sections between 2006 and 2007. We calculated fish density and abundance per sample site and then projected values to the entire drainage area using capture‐mark‐recapture and bootstrapping methods.
We captured 9,266 cutthroat trout, the majority of which (95%) were larger than 70 mm
FL. Of the total catch, 52% were of spawning size (> 149 mm fork length), with less than 3% of legal harvest size (> 300 mm total length). We estimated the drainage population of trout (> 70 mm) to be 296,981 individuals, consisting of 125,479 and 2,996 individuals of spawning and legal harvest‐sized fish, respectively. A comparison of fish density, abundance and population structure between the Livingstone River (catchand‐ release fishery) versus the Oldman River (allowable harvest fishery) indicated that the mainstem Oldman River had more than three times as many fish as the Livingstone River. However, the Livingstone River had more than four times as many legal harvest‐sized fish than the Oldman River. In addition, the catch from the Livingstone River had proportionately more legal harvest‐sized fish than that from the Oldman River. Angling harvests may have altered fish population structure and size in the Oldman River, despite hooking damage in the Livingstone River mainstem being more than double that of the Oldman River mainstem (52% vs. 23%). In addition, data from a 2004 creel survey suggested there were more than twice as many anglers in the Upper Oldman River drainage, at 7,185 ± 13.9%, than legal‐size cutthroat trout, leading to potentially high incidences of hooking damage in the stock.
Over the past decade, declines of Canadian populations of boreal caribou (Rangifer tarandus caribou) have received considerable attention from scientists, government agencies, environmental nongovernmental organizations, Indigenous communities, and the forest industry. Boreal caribou (also known as boreal woodland caribou) was listed as a threatened species in Canada when the Species at Risk Act came into force in June 2003. Many boreal caribou populations have been shown to be decreasing, in some cases precipitously, and empirical evidence from adult survival and calf recruitment surveys indicates that the cumulative effect of habitat disturbance, including that which results from industrial development, is a key driver in the decline. Yet, as scientific understanding of the decline has become clearer, and agreement among scientists and governments about habitat management requirements has increased, campaigns of denial have intensified in the public sphere. In this paper, we examine parallels with climate change rhetoric prolific in the 2000s and show that willful ignorance disguised as skepticism has resulted in public uncertainty despite robust scientific evidence. We show how these strategies of manufactured uncertainty used in climate change denial campaigns have seeped into wildlife management debates, with pernicious results. In this case, it has successfully delayed efforts to effectively address the decline of boreal caribou, which is protected under federal, provincial, and territorial legislation, and inhibited meaningful dialogue about socially acceptable conservation solutions. © 2018 The Wildlife Society.
Catch-and-release (C&R) angling is a powerful tool for reducing impacts on recreationally targeted fishes. Although C&R can be mandated in fisheries through regulation, voluntary adoption and informal management are often critical due to minimal enforcement opportunities. Anglers themselves may play a role in increasing C&R adoption through interpersonal sanctioning (i.e., self-policing). To date, little research has examined factors that predict the willingness of anglers to sanction others’ behavior. We present results from surveys (n = 49) with anglers in Argentina to explore their motivations to sanction other anglers within their stakeholder community. Anglers with the strongest intentions to sanction were younger and more open to adopting best practices, identified fishing as important to their lifestyle, and expressed high environmental concern relative to other anglers. Our findings highlight the role that recreational anglers can play in promoting best practices via interpersonal sanctioning and identify barriers that inhibit this type of action.
Background
Estimates of fishing and natural mortality are important for understanding, and ultimately managing, commercial and recreational fisheries. High reward tags with fixed station acoustic telemetry provides a promising approach to monitoring mortality rates in large lake recreational fisheries. Kootenay Lake is a large lake which supports an important recreational fishery for large Bull Trout and Rainbow Trout.
Methods
Between 2008 and 2013, 88 large (≥500 mm) Bull Trout and 149 large (≥500 mm) Rainbow Trout were marked with an acoustic transmitter and/or high reward ($100) anchor tags in Kootenay Lake. The subsequent detections and angler recaptures were analysed using a Bayesian individual state-space Cormack–Jolly–Seber (CJS) survival model with indicator variable selection.
Results
The final CJS survival model estimated that the annual interval probability of being recaptured by an angler was 0.17 (95% CRI [0.11–0.23]) for Bull Trout and 0.14 (95% CRI [0.09–0.19]) for Rainbow Trout. The annual interval survival probability for Bull Trout was estimated to have declined from 0.91 (95% CRI [0.76–0.97]) in 2009 to just 0.46 (95% CRI [0.24–0.76]) in 2013. Rainbow Trout survival was most strongly affected by spawning. The annual interval survival probability was 0.77 (95% CRI [0.68–0.85]) for a non-spawning Rainbow Trout compared to 0.41 (95% CRI [0.30–0.53]) for a spawner. The probability of spawning increased with the fork length for both species and decreased over the course of the study for Rainbow Trout.
Discussion
Fishing mortality was relatively low and constant while natural mortality was relatively high and variable. The results indicate that angler effort is not the primary driver of short-term population fluctations in the Rainbow Trout abundance. Variation in the probability of Rainbow Trout spawning suggests that the spring escapement at the outflow of Trout Lake may be a less reliable index of abundance than previously assumed. Multi-species stock assessment models need to account for the fact that large Bull Trout are more abundant than large Rainbow Trout in Kootenay Lake.
Research of catch-and-release fishing has included air exposure time as a contributing factor in the lethal and sublethal impacts to fish. However, to our knowledge, no studies have observed the amount of time anglers actually expose fish to air when recreationally fishing. We observed 280 anglers on several waters where catch and release was commonly practiced for trout and timed how long they exposed trout to air before releasing them back to the water. We also noted several angling characteristics to evaluate whether they influenced air exposure times, including the type of gear (fly, lure, bait), fishing on foot or from a boat, handling method (hand, net), and a subjective measure of trout size (small, medium, large). The longest continuous interval that anglers exposed trout to air averaged 26.1 s (range, 0-160 s), and only 4%of the anglers held fish out of thewater continuously for >60 s. Total air exposure averaged 29.4 s, ranged from0 to 165 s, and differed from the longest air exposure by only 3.3 s because most of the released trout (78%) were held out of the water only one time. Anglers who handled trout by hand (rather than using a landing net) and used flies (rather than bait or lures) held fish out of water for less time. Larger trout were exposed to air longer (x = 36.0 s) than small (x = 22.5 s) or medium-sized (x = 27.1 s) trout. However, no angling characteristic increased air exposure by more than 14 s. Fight time averaged 53.0 s and ranged from 7 to 128 s.We conclude that from an air exposure perspective, most of the trout released by anglers in our study were not exposed to air for times that would cause mortality or substantively increase sublethal effects from catch and release.
Exposing fish to air following capture influences postrelease survival and behavior. Air exposure causes acute hypoxia and physical damage to the gill lamellae, resulting in physiological stress and physical damage that increases with air exposure duration. Air exposure duration is a relevant and easily quantified metric for both fishers and managers and can therefore provide a definitive benchmark for improving postrelease survival. Yet, fishers are rarely provided with specific recommendations other than simply to “minimize” air exposure. This is a subjective recommendation, potentially causing confusion and noncompliance. Here we discuss and summarize the literature regarding air exposure thresholds in both commercial and recreational fisheries, the factors influencing these thresholds, and identify knowledge gaps limiting our understanding of tolerance to air exposure in captured fish.
The papers in this Special Section of Ecopsychology explore the mechanisms and benefits of confronting antienvironmental (i.e., unsustainable) behaviors as a means to encourage more environmentally friendly behavior. Confronting is important because it is a means of socially regulating behaviors that affect the common good and increases the frequency of proenvironmental (i.e., conservation) behaviors. Studies explore the role of guilt activation in confronting, barriers to confronting, benefits and constraints regarding using praise versus confrontation, and risks of not confronting antienvironmental behavior when it occurs, particularly by people who are expected to be concerned about environmental problems.
Cryptic, not readily detectable, components of fishing mortality are not routinely accounted for in fisheries management because of a lack of adequate data, and for some components, a lack of accurate estimation methods. Cryptic fishing mortalities can cause adverse ecological effects, are a source of wastage, reduce the sustainability of fishery resources and, when unaccounted for, can cause errors in stock assessments and population models. Sources of cryptic fishing mortality are (1) pre-catch losses, where catch dies from the fishing operation but is not brought onboard when the gear is retrieved, (2) ghost-fishing mortality by fishing gear that was abandoned, lost or discarded, (3) post-release mortality of catch that is retrieved and then released alive but later dies as a result of stress and injury sustained from the fishing interaction, (4) collateral mortalities indirectly caused by various ecological effects of fishing and (5) losses due to synergistic effects of multiple interacting sources of stress and injury from fishing operations, or from cumulative stress and injury caused by repeated sub-lethal interactions with fishing operations. To fill a gap in international guidance on best practices, causes and methods for estimating each component of cryptic fishing mortality are described, and considerations for their effective application are identified. Research priorities to fill gaps in understanding the causes and estimating cryptic mortality are highlighted.
Fishery collapses cause substantial economic and ecological harm, but common management actions often fail to prevent overfishing. Minimum length limits are perhaps the most common fishing regulation used in both commercial and recreational fisheries, but their conservation benefits can be influenced by discard mortality of fish caught and released below the legal length. We constructed a computer model to evaluate how discard mortality could influence the conservation utility of minimum length regulations. We evaluated policy performance across two disparate fish life-history types: short-lived high-productivity (SLHP) and long-lived low-productivity (LLLP) species. For the life-history types, fishing mortality rates and minimum length limits that we examined, length limits alone generally failed to achieve sustainability when discard mortality rate exceeded about 0.2 for SLHP species and 0.05 for LLLP species. At these levels of discard mortality, reductions in overall fishing mortality (e.g. lower fishing effort) were required to prevent recruitment overfishing if fishing mortality was high. Similarly, relatively low discard mortality rates (>0.05) rendered maximum yield unobtainable and caused a substantial shift in the shape of the yield response surfaces. An analysis of fishery efficiency showed that length limits caused the simulated fisheries to be much less efficient, potentially exposing the target species and ecosystem to increased negative effects of the fishing process. Our findings suggest that for overexploited fisheries with moderate-to-high discard mortality rates, reductions in fishing mortality will be required to meet management goals. Resource managers should carefully consider impacts of cryptic mortality sources (e.g. discard mortality) on fishery sustainability, especially in recreational fisheries where release rates are high and effort is increasing in many areas of the world.
Numerous groundfish stocks in both the Atlantic and Pacific are considered overfished, resulting in large-scale fishery closures. Fishing, in addition to simply removing biomass, also truncates the age and size structure of fish populations and often results in localized depletions. We summarize recent research suggesting that an old-growth age structure, combined with a broad spatial distribution of spawning and recruitment, is at least as important as spawning biomass in maintaining long-term sustainable population levels. In particular, there is evidence that older, larger female rockfishes produce larvae that withstand starvation longer and grow faster than the offspring of younger fish, that stocks may actually consist of several reproductively isolated units, and that recruitment may come from only a small and different fraction of the spawning population each year. None of these phenomena is accounted for in current management programs. We examine alternative management measures that address these specific issues and conclude that the best and perhaps only way to ensure old-growth age structure and complex spatial structure in populations of groundfish is through interconnected networks of marine reserves.
Regulations designed to protect recreational fisheries from overexploitation can fail. Regulations such as size and bag limits restrict harvest by individual anglers but not angler effort and therefore not total harvest. Even when individual harvest limits are set to zero (i.e., catch and release), a combination of hooking mortality and noncompliance may lead to fishing mortality rates that are not sustainable if angling effort is sufficiently high. These assertions were tested and quantified by using simulation experiments on a size- and age-structured model developed for a fishery on an adfluvial bull trout population. The functions and rates describing the biology and fishery were derived from a variety of sources, including published and unpublished information on bull trout and, where such sources were unavailable, from other salmonid species. The model predicts that a 40-cm minimum size limit for harvest would maintain viable populations at an annual effort up to 4 angler-hours · ha−1 · year−1, a 65-cm minimum size limit up to 10 angler-hours · ha−1 · year−1, and a catch-and-release fishery up to 18 angler-hours · ha−1 · year−1. The quality of the fisheries that developed under these three alternative regulations varied substantially with the amount of angler effort imposed. Uncertainty in the minimum population size necessary to ensure sustainability, recruits per unit stock, catchability, hooking mortality rate, and noncompliance rate modifies quantitative predictions, but the qualitative patterns are general. If anglers respond dynamically to variation in the quality of fishing, then the ability of size limit regulations to sustain fisheries is further compromised. The combination of life history and fishery traits such as slow growth, late age at maturity, low fecundity, longevity, and high catchability render adfluvial bull trout particularly susceptible to overfishing, even within relatively narrow bounds of angler effort.
Rainbow trout (Oncorhynchus mykiss) which were air exposed for 60 s after exhaustive exercise initially had a much larger extracellular acidosis than trout which were only exercised. In both groups, however, plasma pH returned to normal by 4 h. Blood lactate concentrations were also greater in the air-exposed fish and continued to increase throughout the experiment. During air exposure, there was retention of carbon dioxide in the blood, and oxygen tension (Po2) and hemoglobin:oxygen carriage (Hb:O2) both fell by over 80%. After 30 min of recovery, however, blood gases resembled those in fish which were only exercised. Finally, survival after 12 h was 10% in control fish and 88% in the exercised fish but fell to 62 and 28% in fish which were air exposed for 30 and 60 s, respectively, after exercise. These results indicate that the brief period of air exposure which occurs in many "catch and release" fisheries is a significant additional stress which may ultimately influence whether a released fish survives.
In an effort to accelerate the ongoing paradigm shift in fi sheries science from the traditional single-species mindset toward more ecosystem-based approaches, we offer the following "commandments" as action items for bridging the gap between general principles and specifi c methodologies. 1. Keep a perspective that is holistic, risk-averse, and adaptive. 2. Question key assumptions, no matter how basic. 3. Maintain old-growth age structure in fi sh populations. 4. Characterize and maintain the natural spatial structure of fi sh stocks. 5. Characterize and maintain viable fi sh habitats. 6. Characterize and maintain ecosystem resilience. 7. Identify and maintain critical food web connections. 8. Account for ecosystem change through time. 9. Account for evolutionary change caused by fi shing. 10. Implement an approach that is integrated, interdisciplinary, and inclusive. Although the shift in worldview embodied in these commandments can occur immediately without additional funding, full implementation of ecosystem-based fi sheries science will require an expanded empirical basis as well as novel approaches to modeling. We believe that pursuing these action items is essential for productive marine fi sheries to become truly sustainable for present and future generations.
Air exposure has been hypothesized as one of the primary stressors present during catch-and-release angling. However, there are few studies that systematically vary air exposure duration and evaluate the consequences on individual fish. Here, we evaluated the short-term, sublethal effects of exercise (to simulate angling) and air exposure on the swimming performance of hatchery brook trout Salvelinus fontinalis at 10°C. The duration of the angling event (i.e., chasing the fish by hand) was held constant at 30 s, while air exposure duration was systematically varied between 0, 30, 60, and 120 s. The results showed that air exposures of 60 s or less did not affect swimming performance. However, air exposure of 120 s resulted in a dramatic (∼75%) reduction in swimming performance. In fact, nearly half of the fish held out of the water for 120 s were unwilling or unable to swim at all. No mortality was observed after any of the treatments (fish were monitored for 3 months). This work suggests that fish possess air exposure thresholds that, once exceeded, result in performance impairments. Fish released after extended air exposure may become easy prey for predators or could be displaced downstream by flows in fluvial environments. We conclude that air exposure should be restricted to less than 60 s and ideally should be avoided entirely.
Understanding the vulnerability of aquatic species and habitats under climate change is critical for conservation and management of freshwater systems. Climate warming is predicted to increase water temperatures in freshwater ecosystems worldwide, yet few studies have developed spatially explicit modelling tools for understanding the potential impacts. We parameterized a nonspatial model, a spatial flow-routed model, and a spatial hierarchical model to predict August stream temperatures (22-m resolution) throughout the Flathead River Basin, USA and Canada. Model comparisons showed that the spatial models performed significantly better than the nonspatial model, explaining the spatial autocorrelation found between sites. The spatial hierarchical model explained 82% of the variation in summer mean (August) stream temperatures and was used to estimate thermal regimes for threatened bull trout (Salvelinus confluentus) habitats, one of the most thermally sensitive coldwater species in western North America. The model estimated summer thermal regimes of spawning and rearing habitats at
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.
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.
SYNOPSIS. We examine the variation in egg sizes of marine teleosts and evaluate the maternal contribution to this variability. At the species level, egg sizes in 309 North Atlantic fishes range from 0.3 to 18.0 mm diameter (median = 1.1), size at hatching varies directly with egg size, and large adult size is associated with large eggs but the relationship is weak. Within populations, egg sizes are distributed normally with a median coefficient of variation of 4% (n = 56 species). Egg size varied among females in all cases for which female-level data were found. Estimates of the variance components of egg size due to females were found for three species and, as a percentage of total variance, are 71 % for capelin, Mallotus villosus , 46% for winter flounder, Pleuronectes americanus , and 35% for Atlantic cod, Gadus morhua . For cod, which spawn multiple egg batches per year, an additional batches-within-females component was estimated to be 26%. Size at hatching also differs among sibgroups and is generally directly related to egg size at the individual level. We modelled fish growth by allowing individuals to grow at exponential rates from a normal distribution of initial sizes. Comparing size variation in model fish to empirical evidence suggests that variation in initial sizes, propagated by growth, could account for a large fraction of the size variation observed months after hatching in natural populations. We view size variation in young marine fishes to be largely of maternal origin and environmentally modulated, which if true has special consequences for fisheries and aquaculture.
Research by Berkeley et al. and by Bobko and Berkeley has recently demonstrated that older individuals of some fish species produce larvae that have substantially better survival potential than do larvae from younger fishes. These new findings augment established knowledge that larger individuals usually have exponentially greater fecundity. This is important because commercial fisheries and especially recreational fishing often target the larger fish. The protection of larger or older individuals is necessary for the sustainability of species currently exploited by humans.
Steelhead, the anadromous form of rainbow trout (Oncorhynchus mykiss), is one of the most coveted recreationally
targeted salmonids worldwide, and catch-and-release (C&R) is commonly used as a conservation
strategy to protect wild stocks. Nevertheless, little research has examined how wild steelhead respond to capture
and handling. During a summer-run recreational fishery on the Bulkley River in British Columbia, we used nonlethal
blood sampling and radio telemetry to assess the physiological stress response, post-release behaviour, and
survival of wild steelhead exposed to either 0 s, 10 s, or 30 s of air exposure, over a range of water temperatures,
fight times, and landing methods. Steelhead that were air exposed following landing had greater reflex impairment
and moved further downstream immediately following release than fish kept in the water, though there
was no observed difference in movement two weeks after capture. Overall, angled fish had significantly greater
blood lactate levels than baseline levels (obtained from a subsample of fish dip netted from the river) suggesting
a general stress response to angling and handling. Regardless of air exposure treatment, water temperature was
positively associated with blood lactate and negatively associated with blood pH. Other variables such as fish
body size (mm) and fight time (s) had little influence on any of the physiological or behavioural variables.
Estimated 3-day survival of steelhead was 95.5%, with deep-hooking as the primary source of mortality. Overwinter
mortality of caught-and-released fish was estimated at 10.5%, with an estimated total pre-spawn mortality
of 15.0%. This study is the first to evaluate the factors that influence C&R outcomes in wild steelhead in a
recreational fishery. Findings suggest that steelhead anglers should limit air exposure to less than 10 s, and that
anglers should be cautious (minimize handling and air exposure) when water temperatures are warmer.
In many parts of sub-Saharan Africa community water points are provided through external support in the form of enhanced boreholes fitted with hand pumps. The external agency supplying the improved water source commonly provides maintenance training and assists in organising a governance plan for the water point. Despite its apparent virtues the Village-Level Operation and Maintenance model still experiences high levels of water point failures, even where the technical training and material conditions are adequate. There has been relatively little investigation of the institutional factors that may influence the cases where villages successfully maintain their shared water source infrastructure. This research investigated five villages in central Malawi where communities had maintained their water point hand pumps for periods exceeding 10 years. The results point to the importance of informal institutions giving primacy to ad-hoc 'rules-in-use' that suit the local context, and adapting forms of free-rider sanctions that are typically minor, low level and triangulated with local norms and behaviours. The findings highlight collective action that is successful through day-to-day adaption and that serves to institutionalise cooperative behaviour through appeals to norms.
Catch-and-release regulations are among the most common types of fishing regulations. In recent years, concerns have arisen regarding the exposure of fish to air during catch-and-release angling. The purpose of our study was to quantify the length of time angled fish were exposed to air by anglers in a typical catch-and-release fishery and relate it to the lengths of time reported to produce negative effects. In total, 312 individual anglers were observed on the South Fork Snake River, Idaho, from May through August 2016. Fight time varied from 1.1 s to 230.0 s, and average fight time was 40.0 s (SD=36.8). Total air exposure times varied from 0.0 s to 91.8 s and averaged 19.3 s (SD=15.0). Though not statistically significant, a trend in reduced fight times was observed when anglers were guided and increased air exposure times when a net was used and a picture was taken. Results of the current study suggest that anglers expose fish to air for periods that are much less than those reported to cause mortality.
Previous research has shown that social sanctions can catalyze and buttress conservation efforts; however, it is unclear how willing people are to confront (e.g., express verbal or nonverbal approval or disapproval) environmental transgressions. In the present study, willingness to sanction was measured with respect to recycling. Results showed that there was an asymmetry between approval and disapproval. That is, while participants expressed approval for the commission of a positive conservation behavior (recycling), they did not express disapproval for the omission of the same behavior. When asked about their willingness to sanction, participants were more willing to reward than punish and more willing to impose subtle versus overt sanctions. Willingness to impose each type of social sanction was correlated with the perceived effectiveness of that sanction. Overall, results showed that students were hesitant to confront environmental transgressors with social sanctions. It is proposed that creating a culture of conservation requires a willingness to confront and that the hesitation to impose social sanctions is due to a lack of metanorms that support the sanctioning.
Whenever satisfied anglers are an important objective of recreational fisheries management, understanding how trip outcomes influence satisfaction reports is critical. While anglers, generally, prefer high catch rates and large fish, the relative importance of these catch outcomes for catch satisfaction has not been established across species and angler types. We examined relationships between angler specialization, trip outcomes (both catch and non-catch characteristics such as crowding), and catch satisfaction across six freshwater fish species in northern Germany. As expected, catch satisfaction was primarily determined by catch rate and fish size in all fish species; however, the relative importance of these two outcomes varied considerably across species and among angler types that differed by commitment to fishing. We found a diminishing marginal return of satisfaction for increasing catch rate for all but small-bodied cyprinid species, while increasing size of largest retained fish monotonically increased catch satisfaction in all species we examined. Non-catch outcomes (e.g., the number of other anglers seen while fishing) also had a significant negative influence on catch satisfaction, suggesting that non-catch factors are important in establishing expectations and for contextual evaluation of catch outcomes. We also determined that diversified trips made anglers more satisfied and that all else being equal, specialized anglers increased catch satisfaction from travel and fishing time. The results highlight the importance for managers to consider their particular mix of anglers as well as the fish species present when setting regulations aimed at increasing angler satisfaction.
The assumption that animals released from fishing gears survive has frequently been scrutinized by researchers in recent years. Mortality estimates from these research efforts can be incorporated into management models to ensure the sustainability of fisheries and the conservation of threatened species. Post-release mortality estimates are typically made by holding the catch in a tank, pen or cage for short-term monitoring (e.g. 48 h). These estimates may be inaccurate in some cases because they fail to integrate the challenges of the wild environment. Most obvious among these challenges is predator evasion. Stress and injury from a capture experience can temporarily impair physiological capacity and alter behaviour in released animals, a period during which predation risk is likely elevated. In large-scale commercial fisheries, predators have adapted their behaviour to capitalize on impaired fishes being discarded, while in recreational catch-and-release fisheries, exercise and air exposure can similarly impede the capacity for released fish to evade opportunistic predators. Owing to the indirect and often cryptic nature of this source of mortality, very few studies have attempted to document it. A survey of the literature demonstrated that <2% of the papers in the combined realms of bycatch and catch-and-release have directly addressed or considered post-release predation. Future research should combine field telemetry and laboratory studies using both natural and simulated predation encounters and incorporate physiological and behavioural endpoints. Quite simply, predation is an understudied and underappreciated contributor to the mortality of animals released from fishing gears.
Over the past 20 years, there has been a dramatic increase in the use of physiological tools and experimental approaches for the study of the biological consequences of catch‐and‐release angling practices for fishes. Beyond simply documenting problems, physiological data are also being used to test and refine different strategies for handling fish such that stress is minimised and survival probability maximised, and in some cases, even for assessing and facilitating recovery post‐release. The inherent sensitivity of physiological processes means that nearly every study conducted has found some level of – unavoidable – physiological disturbance arising from recreational capture and subsequent release. An underlying tenet of catch‐and‐release studies that incorporate physiological tools is that a link exists between physiological status and fitness. In reality, finding such relationships has been elusive, with further extensions of individual‐level impacts to fish populations even more dubious. A focus of this article is to describe some of the challenges related to experimental design and interpretation that arise when using physiological tools for the study of the biological consequences of catch‐and‐release angling. Means of overcoming these challenges and the extrapolation of physiological data from individuals to the population level are discussed. The argument is presented that even if it is difficult to demonstrate strong links to mortality or other fitness measures, let alone population‐level impacts of catch‐and‐release, there remains merit in using physiological tools as objective indicators of fish welfare, which is an increasing concern in recreational fisheries. The overarching objective of this paper is to provide a balanced critique of the use of physiological approaches in catch‐and‐release science and of their role in providing meaningful information for anglers and managers.
The sport fishery for walleyes Stizostedion vitreum in Alberta, Canada, has declined severely because of high angling pressure relative to the low productivity of northern fisheries. Following extensive public consultation, highly restrictive length and bag limits were implemented on all walleye fisheries, clearly increasing the opportunities and temptations for anglers to illegally harvest fish. An estimate of illegal harvest was derived from data gathered at 29 sport fisheries in Alberta from 1991 to 1998. The technique involved counting protected-length fish in anglers' creels and comparing these numbers to the numbers of protected-length fish released. I avoided anglers' exaggeration of released walleye numbers by comparing the ratios of the lengths of fish caught by test angling to those of fish retained and reported by anglers, as recorded by creel clerks. The average illegal harvest level was high; 18.4% (range = 0.2–68.8%) of protected-length walleyes caught were kept. Illegal harvest was lowest at fisheries with catch-and-release regulations and highest at fisheries managed with slot-length limits. Of particular importance to fisheries managers, illegal harvest was inversely related to catch rate, thereby creating a strong depensatory response to a fishery decline. Other indices of compliance (creel clerks' reports of illegal harvest, the percentage of protected-length fish in anglers' creels, and angler infraction rates) were less useful indicators of illegal harvest. To counteract the negative effects of illegal harvest, managers should (1) avoid using length limits at lakes expected to have high illegal harvest levels, (2) use slot-length limits only at lakes where catch rates are expected to be high, and (3) not rely on low infraction rates or low percentages of protected-length fish in creels to imply high levels of compliance.
Length‐limit regulations and promotion of catch‐and‐release fishing have become increasingly important management approaches for recreational fisheries. We review‐studies on catch‐and‐release (hooking) mortality gathered from the existing fisheries literature and from a survey of fisheries management agencies in all 50 states, the U.S. government, all Canadian provinces, and selected academic and research institutions. We identified hooking mortality estimates for 32 taxa. Most studies dealt with salmonids, centrarchids (especially black basses, Micropterus spp.), and percids (especially walleye, Stizostedion vitreum). Within and among species, differences in percent mortality were reported in association with bait type (artificial vs. natural), hook type (number of hooks, hook size, and barbs), season/ temperature, water depth (depressurization), anatomical location of hook wound, and individual size. Although most hooking mortalities occur within 24 h, the use of initial plus delayed mortality provides a more complete estimate of mortality. Single hooks (especially when used in conjunction with natural baits) resulted in higher mortalities than treble hooks. Environmental conditions (notably high water temperature and low dissolved oxygen) are important to overall mortality related to hooking, playing, and handling. Mortalities were highly variable; occasionally exceeding 30% among red drum (Sciaenops ocellatus), smallmouth bass (M. dolomieu), largemouth bass (M. salmoides), cutthroat trout (Oncorhynchus clarki), and catfishes (Ictaluridae), and 68% among spotted seatrout (Cynoscion nebulosus), bluegills (Lepomis macrocbirus), crappies, (Pomoxis spp.), striped bass (Morqne saxatilis), and coho salmon (O. kisutch). Lake trout (Salvelinus namaycush) and pikes (Esoddae) had mortalities under 15%. The many variables potentially affecting hooking mortality may make optimal management of particular species and water bodies difficult using regional‐level (e.g., statewide) management regulations.
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.
The bull trout Salvelinus confluentus is believed to be among the most thermally sensitive species in coldwater habitats in western North America. We conducted a comprehensive field assessment of thermal habitat associations throughout the southern margin of the species' range. We developed models of thermal habitat associations using two data sets representing a geographically diverse range of sites and sampling methods. In both data sets, maximum temperature was strongly associated with the distribution of bull trout. In spite of the potential biases in these data sets, model predictions were similar. In both cases, the probability of the occurrence of bull trout exceeded 50% when the maximum daily temperature was less than 14-16°C, a result that is consistent with recent laboratory-based thermal tolerances. In one data set, we modeled the association between the distribution of bull trout and environmental variables, including temperature, instream cover, channel form, substrate, and the abundance of native and nonnative salmonid fishes. Only temperature was strongly associated with the distribution of bull trout. Our results and related studies of landscape habitat associations suggest that conservation efforts for bull trout would benefit from a focus on maintaining and restoring large and interconnected coldwater habitats.
A length-categorization system was developed to assess structure of fish stocks with greater precision than is possible using Proportional Stock Density (PSD). Three new size categories - preferred, memorable, and trophy - were developed to accompany previously established stock and quality lengths. Like minimum stock and quality lengths, minimum lengths for the new categories are defined as percentage lengths of the all-tackle, world-record fish. Length ranges from or near which minimum stock, quality, preferred, memorable, and trophy lengths should be selected were computed for all freshwater fish species having a world-record length listed by the International Game Fish Association in 1982. Minimum lengths corresponding to each of the five size categories are proposed for several species. By arraying samples of fish population data or angler catch data according to the five size-group categories, a length-frequency distribution can be easily assessed and verbalized. Relative Stock Density (RSD) or models for catch rates also can be developed to set management objectives that are easily understandable, yet reflect recruitment, mortality, and growth functions of fish populations and communities. Desirable percentages and catch rates for size-group categories may differ among individual waters or geographic regions depending upon management objectives and the capacity to produce the species of interest.
Few studies have assessed catch-and-release mortality of salmonids at water temperatures of 23 degrees C or above, despite predictions of warming stream temperatures due to climate change. The primary objective of this study was to measure the catch-and-release mortality of rainbow trout Oncorhynchus mykiss, brown trout Salmo trutta, and mountain whitefish Prosopium williamsoni in three water temperature treatments, namely, when daily maximum water temperatures were cool (<20 degrees C), warm (20-22.9 degrees C), and hot (>= 23 degrees C). A secondary objective was to assess the catch-and-release mortality of salmonids angled in morning and evening within the water temperature treatments. These objectives were related to Montana Fish, Wildlife and Parks' drought fishing closure policy. Angling (fly-fishing only) occurred in the Gallatin and Smith rivers. All angled fish were confined to in-stream holding cages and monitored for mortality for 72 h. Mortality of rainbow trout peaked at 16% in the Gallatin River and 9% in the Smith River during the hot treatment. Mortality of brown trout was less than 5% in all water temperature treatments in both rivers. Mountain whitefish mortality peaked at 28% in the hot treatment in the Smith River. No mortality for any species occurred in either river when daily maximum water temperatures were less than 20 degrees C. Mortality of rainbow trout peaked at 16% in the evening hot treatment in the Smith River. Mortality rates of brown trout and mountain whitefish were not related to time of day. The catch-and-release mortality rates presented here probably represent fishing mortality given that most anglers in southwestern Montana practice catch-and-release angling. The mortality values we observed were lower than predicted (<30%) given reports in the literature. The difference is probably related to the in situ nature of the study and periods of cooler water temperatures between peaks, which facilitated recovery from thermal stress.
We searched major electronic databases to identify peer-reviewed literature investigating the role of temperature on the stress response and mortality of captured and released fish. We identified 83 studies that fit these criteria, the majority of which were conducted in North America (81%) on freshwater fish (76%) in the orders Perciformes (52%) and Salmoniformes (28%). We found that hook-and-line fisheries (65% of all studies) were more commonly studied than all net fisheries combined (24%). Despite the wide recognition for many species that high water temperatures exacerbate the effects of capture on released fish, this review is the first to quantitatively investigate this problem, finding that warming contributed to both mortality and indices of stress in 70% of articles that measured each of those endpoints. However, more than half (58%) of the articles failed to place the experimental temperatures into a biological context, therefore limiting their broad applicability to management. Integration of survival and sublethal effects to investigate mechanisms of fish mortality was relatively rare (28%). Collectively, the results suggest that capture–release mortality increases at temperatures within, rather than above, species-specific thermal preferenda. We illustrate how knowledge of ecologically relevant high temperatures in the capture and release of fish can be incorporated into management, which will become increasingly important as climate change exerts additional pressure on fish and fisheries.
a b s t r a c t Research on a wide range of fish species has revealed that deep hooking is perhaps the single most important determinant of injury and post-release mortality in recreational fisheries. However, there is little information on the best option for dealing with deeply hooked fish that are to be released; should the line be cut or should the hook be removed? Using bluegill sunfish (Lepomis macrochirus) as a model we investigated sublethal (e.g., swimming performance, physiological condition, injury levels) and lethal consequences associated with removal of deeply ingested hooks versus cutting the line and leaving the hook embedded in the esophagus, relative to shallowly hooked controls. Neither hook retention nor deep hook-removal altered the swimming performance of the fish in this study relative to controls. However, there was evidence of short-term physiological disturbance. For example, hematocrit was reduced for fish that had hooks removed, consistent with visual observations of bleeding. In addition, blood glucose levels tended to be higher and plasma Na + levels tended to be lower in deeply hooked fish that had hooks removed indicating stress and ionic imbalance even 24 h after capture. During holding experiments we noted the highest mortality levels in fish for which the hook was removed (33% after 48 h and 44% after 10 days). Mortality rates were lowest for the controls (0% after 48 h and 4% after 10 days) and intermediate for the line-cut treatment (8% after 48 h and 12.5% after 10 days). After 48 h, 45.5% of the fish from the line-cut treatment group were able to expel the hook originally embedded in their esophagus, and at the end of the 10 day study, 71.4% had expelled the hook. Even with the hook left in the esophagus, fish were able to feed although at lower rates than controls during the first 48 h of holding. By 10 days post-capture, there were no differences in feeding rates as evidenced by growth patterns among the treatment groups, nor were there differences in the hepatosomatic index. Collectively, the findings from this study demonstrate that cutting the line is a more effective release method than removing the hook when fish are deeply hooked. As such, angler education efforts should focus on disseminating this message to anglers as well as encouraging the use of gear and techniques that minimize incidences of deep hooking (e.g., circle hooks, non-organic bait).
Relative body size has long been recognized as a factor influencing repro-ductive success in fishes, but maternal age has only recently been considered. We monitored growth and starvation resistance in larvae from 20 female black rockfish (Sebastes melan-ops), ranging in age from five to 17 years. Larvae from the oldest females in our experiments had growth rates more than three times as fast and survived starvation more than twice as long as larvae from the youngest females. Female age was a far better predictor of larval performance than female size. The apparent underlying mechanism is a greater provisioning of larvae with energy-rich triacylglycerol (TAG) lipids as female age increases. The volume of the oil globule (composed primarily of TAG) present in larvae at parturition increases with maternal age and is correlated with subsequent growth and survival. These results suggest that progeny from older females can survive under a broader range of environmental conditions compared to progeny from younger females. Age truncation commonly induced by fisheries may, therefore, have severe consequences for long-term sustainability of fish populations.
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.
The literature on common property-based resource management comprises many important studies that seek to specify the conditions under which groups of users will self-organize and sustainably govern resources upon which they depend. Using three of the more comprehensive such studies, and with an extensive review of writings on the commons, this paper demonstrates that the enterprise of generating lists of conditions under which commons are governed sustainably is a flawed and impossibly costly research task. For a way out, the paper examines the relative merits of statistical, comparative, and case study approaches to studying the commons. It ends with a plea for careful research design and sample selection, construction of causal mechanisms, and a shift toward comparative and statistical rather than single-case analyses. Such steps are necessary for a coherent, empirically-relevant theory of the commons.
At present, there is a reasonable understanding of the independent effects of catch-and-release (C&R) angling stressors, such as air exposure and water temperature, on endpoints such as physiological disturbance, behavioural impairment and mortality. However, little is known about the multiplicative or interactive nature of these different C&R stressors. This study used bluegill (Lepomis macrochirus) as a model to evaluate the combined effects of water temperature and air exposure on fish behaviour, equilibrium status and short-term mortality following C&R. Experiments were replicated over 3 days with different ambient water temperatures (18.3, 22.8 and 27.4 °C). On each day, fish were captured by standard angling techniques, exposed to a range of air exposure durations (0, 30, 60, 120, 240, 480 and 960 s), and subsequently monitored for behavioural changes (within the first 300 s) and short-term (48 h) delayed mortality. Additional fish were captured by seine net for use as controls. There was an interactive effect of temperature and air exposure, whereby fish exposed to the highest temperature and longer air exposure durations lost equilibrium more often and had depressed ventilation rates relative to fish exposed to minimal air exposure and the lowest temperature. Immediate mortality at the lowest temperatures was negligible. However, significant delayed mortality (up to 80%) was noted at the highest water temperature (27.4 °C) in fish exposed to the three longest air exposure groups. In addition, at 27.4 °C, mortality among fish exposed to 480 and 960 s occurred at a faster rate than in any other treatment group. These results indicate that at low to moderate water temperatures, extended air exposure for bluegill may result in little mortality. However, at high water temperatures, short-term mortality (within 48 h) can be substantial, especially for fish that experience extended air exposure durations. Anglers and managers must recognize that C&R stressors can interact to have more dire consequences than when applied independently.
This study challenges the oversimplified way in which abstract and bureaucratic 'design principles' derived from resource management literature are translated into development policy and practice, in pursuit of robust and enduring institutions. Drawing on research in the Usangu Basin, Tanzania, it explores the socially embedded nature of institutions for common property resource management and collective action. The concept of 'institutional bricolage' is outlined; a process by which people consciously and unconsciously draw on existing social and cultural arrangements to shape institutions in response to changing situations. Contrary to much theory, this study shows that institutions formed through bricolage are a dynamic mixture of the 'modern' and 'traditional', 'formal' and 'informal'.
Sustained swimming at 0.9 BL s(-)(1), where BL is fork body length, following a bout of exhaustive exercise enhanced recovery of metabolite and acid-base status in rainbow trout compared with fish held in still water. The most striking effect of an active recovery was a total absence of the elevation cortisol concentration typically associated with exhaustive exercise. In fish swimming at 0. 9 BL s(-)(1), plasma cortisol levels averaged 20-25 ng ml(-)(1) throughout the 6 h recovery period. In contrast, plasma cortisol increased to a peak level of 128.4+/-11.2 ng ml(-)(1) (mean +/- s.e. m., N=6) in fish recovering in still water. Muscle glycogen was completely resynthesized and lactate cleared within 2 h of exercise in swimming fish compared with more than 6 h required in the fish held in still water. Similarly, blood lactate level and acid-base status were restored more quickly in the swimming fish. These observations suggest that the prolonged recovery usually associated with exhaustive exercise in rainbow trout is due to elevations in plasma cortisol concentration and that the stimulus for cortisol release is not exercise per se, but rather post-exercise inactivity.
Bull Trout Conservation Management Plan 2012-17. Alberta Sustainable Resource Development, Species at Risk Conservation Management Plan No
ASRD, 2012. (Alberta Sustainable Resource Development). Bull Trout Conservation
Management Plan 2012-17. Alberta Sustainable Resource Development, Species at
Risk Conservation Management Plan No. 8. Edmonton, AB. pp. 90 pp.
Standards for the Ethical Use of Fishes in Alberta
AESRD, 2013. Standards for the Ethical Use of Fishes in Alberta. Retrieved December
2018. https://open.alberta.ca/dataset/a14f1a76-6ba7-4df8-99e4-b7fc489f5f46/
resource/8eae46f1-4067-4046-83ef-50c88629ebd0/download/standardethicaluseoffishesinalberta-may2013a.pdf.