Article

Stocking Trends: A Quantitative Review of Governmental Fish Stocking in the United States, 1931 to 2004

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Abstract

This article provides a quantitative review of the type, number, and estimated weight of the fish stocked by the 50 state agencies and the U.S. Fish and Wildlife Service in the United States in 2004. I examined trends in the light of data from earlier reports dating back to 1931. Among other things, this analysis shows that 1.7 billion fish were stocked by these agencies in 2004, representing 104 types of fish weighing an estimated 19.8 million kg. This was the largest number of types of fish (species, subspecies, and hybrids) and the largest total weight of fish ever stocked for those years for which information was available. Because many fish are being stocked at larger sizes, the total number of fish stocked in 2004 was in fact lower than in the first half of the twentieth century. Reflecting a long-term trend, most of the stocking was done by state agencies. The majority of the fish stocked (by estimated weight) were in western states and the most commonly stocked fish by this measure were coldwater sportfish, especially rainbow trout (Oncorhynchus mykiss).

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... Therefore, in practice it is difficult to maintain records of the stocking practices conducted by hundreds to thousands of local angling clubs, and the mandatory record-keeping of stocking practices is lacking in many countries (Aas et al., 2018). In this context, survey-based studies can provide a quantitative assessment of freshwater fish stocking practices at a national scale (e.g., Halverson, 2008;Hunt & Jones, 2018;Mickiewicz, 2013), and such studies are needed to provide basic data on the scope of the stocking practice. ...
... In Germany, in 2010, the stocking volume per angler was approximately 53 fishes, or 2.5 kg fish/angler/year . In the USA, it was estimated that 1.7 billion fishes (19.800 t) were stocked in 2004 (Halverson, 2008). There are 27.641 million anglers in the USA , leading to stocking of 62 fish species and 0.7 kg/recreational angler/ ...
... In Australia, the amount of fish stock was 12 million fishes and 131 t/year (Hunt & Jones, 2018). With 3.36 millions anglers , stocking was estimated to be 3. Stocking trends in the USA suggest that managers increasingly rely on larger fish sizes (Halverson, 2008), presumably because it was found that smaller fishes usually produce poorer stocking outcomes (Johnston et al., 2018). In general, the amount of fish stocked in France was variable among species, and within species there were variations in the biomass and in the number of individuals stocked. ...
Article
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.
... An estimated 1.75 × 10 9 fishes, weighing 20 × 10 6 kg, were stocked by the state and federal governments in the United States in 2004 (Halverson, 2008). These included fishes as fry, fingerling and larger fishes and were primarily freshwater or anadromous. ...
... From an aquaculture perspective, O. mykiss readily feed on pellets throughout their life and tolerate hatchery and rearing facilities well. Between 1931 and 2004, the number of fishes stocked has been reduced by 80% or more, but the size of the fishes has increased (Halverson, 2008). Halverson (2008) further indicated that stocking programmes in the first half of the 20th century were originally intended to support recreational and commercial fisheries. ...
... Between 1931 and 2004, the number of fishes stocked has been reduced by 80% or more, but the size of the fishes has increased (Halverson, 2008). Halverson (2008) further indicated that stocking programmes in the first half of the 20th century were originally intended to support recreational and commercial fisheries. Of the current 104 species he described, however, 37 were considered threatened, endangered or species of special concern. ...
Chapter
Freshwater fisheries in the United States are structured from three driving influences: fish diversity, habitats and human users. The United States has over 1200 species of fishes, many of which are endemic to North America, such as members of the Centrarchidae (black basses and sunfish) family, while other classifications (e.g. Salmonidae) transcend political and geographical boundaries and are more ubiquitous. The specific diversity of fishes in the United States varies by geographical region, typically related to physical habitat, including rivers, streams, ponds, lakes and reservoirs. Cool- and coldwater fisheries are found along the northern states and mountain areas, while warmwater fisheries encompass much of the rest of the country. Historical use of these fishes was for consumption, with harvest coming from subsistence and commercial fishing activities. Increases in the demand for fishes and a denigration of water quality readily apparent in the beginning of the 20th century threatened the sustaining fisheries benefit. In the past 100 years, a scientific approach towards this resource has provided stewardship, particularly as recreational fishing has become popular. Contemporary management tenets are multidimensional and take on the holistic ecosystem approaches needed for successful management of these diverse fisheries resources.
... In addition, if the responsible approach assessment is supported with fish stocking data analyses, which are also often lacking in fish stocking discussions, it provides an even more powerful review opportunity. Data including species types, sizes of fish, and stocking water types encompassing spatial and temporal trends (see Halverson, 2008 for an example) are particularly useful as these are often highly debated aspects of fish stocking. To the authors' knowledge, no studies attempt to combine the approaches, particularly over broad jurisdictional areas such as an entire country. ...
... Ingram et al. (2011) also stated that 71% of Murray cod stocked since 2000/01 in the Murray-Darling Basin were stocked into impoundments. Halverson (2008) conducted similar analyses for USA fish stocking between 1931 and 2004 and also found in a reduction of salmonids stocked but increases in weight over time. Consistent with the current study, Halverson (2008) cited reasons for the changes in stocking practices to include the preference to plant fish rather than establish populations, and increased survival from larger fish. ...
... Halverson (2008) conducted similar analyses for USA fish stocking between 1931 and 2004 and also found in a reduction of salmonids stocked but increases in weight over time. Consistent with the current study, Halverson (2008) cited reasons for the changes in stocking practices to include the preference to plant fish rather than establish populations, and increased survival from larger fish. These studies support the trends reflected in the current study and collectively highlight the importance of considering the large-scale changes in fish stocking over time to inform future fish stocking practices and debates. ...
Article
Full-text available
Fish stocking is commonly used in developed countries and aims to improve recreational fish stocks and rebuild threatened species populations. Fish stocking is often contentious due to its high investment, limited scientific evaluation, and typically divided opinion from key stakeholders. Debates over the efficacy and effects of fish stocking continue to occur in the absence of key information about current and past practices, and their degree of alignment with the accepted responsible approach previously published in platform papers. Consequently, using Australia as a case study, this paper presents a framework for assessing fish stocking practices. First, recent fish stocking practices were benchmarked by compiling freshwater fish stocking statistics from every state and territory in Australia. Over 84 million fish were found to have been stocked in Australia between 2009 and 2015, with recreational species, both native and salmonid, comprising the majority of numbers and weight of fish stocked, respectively. Second, historical trends in fish stocking were assessed over a 106 year period across one major jurisdiction, finding significant changes in practices including a strong move toward native species, and a reduction in the number of salmonids stocked, but an increase in size. Third, a literature review was conducted to evaluate Australia's fish stocking practices and found they could be generally considered responsible, however improvements could be made in areas highlighted. This study provides a valuable framework to assess fish stocking practices, aiding our understanding, informing future discussion, and fostering better outcomes from this popular fisheries management tool.
... Stocking remains a popular, though increasingly controversial, management in- tervention. For example, in the United States, more than 171 million "coldwater sport fish" were stocked by state and federal agencies in 2004 (Halverson 2008). Stocking has introduced trout and char species into many areas where they were not indigenous, often resulting in robust populations of wild-reproducing, nonnative fish, which sometimes have had unintended consequences on native fauna. ...
... Fish introductions tracked the expansion of the rail network (Luton 1985;Krueger and May 1991). Many of these early exotic introductions were made by public citizens groups or by the U.S. Fish Commission, precursor to the U.S. Fish and Wildlife Service (Halverson 2008). Brown Trout and Brook Trout were moved from east to west, and Rainbow Trout were moved west to east (MacCrimmon 1971;Crawford and Muir 2008). ...
... The continual restocking of wild fish populations with hatchery reared fish plays a major role in conserving recreational fisheries for trout (e.g. Halverson, 2008). However, the extent to which restocking enhances fisheries that include both wild and hatchery produced fish is often poorly understood, due to difficulties in accurately identifying the origin of fish caught during recapture surveys. ...
... Worldwide, many rivers and lakes that currently have standing stocks of rainbow and brown trout are replenished with hatchery reared fish to help enhance recreational fishing (e.g. Halverson, 2008). However, if suitable habitat ranges alter or constrict, the distribution and abundances of many freshwater species will change as well (Ficke et al., 2007;Wade et al., 2013). ...
Article
Suitable habitat for many temperate freshwater species of salmonids is predicted to dramatically decline, yet many hatcheries still release millions of juvenile salmonids into rivers and lakes annually with little or no post release monitoring. This is, in part, because marking of hatchery reared fish is often not compulsory and currently available marking methods are either costly, cause high mortalities, are inconvenient to apply, or have poor long-term retention rates. To help overcome these limitations, we tested two recently validated stable isotope mass marking methods for Atlantic salmon (larval and egg immersion), to determine if a suitable low cost, easy to apply, fish friendly marking method could be achieved for two of the most widely stocked freshwater salmonids worldwide: brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss. Egg immersion using 1000μgL⁻¹ of ¹³⁷Ba and ¹³⁶Ba over a 2h period did not create detectable marks in the otoliths of brown or rainbow trout. In contrast, larval immersion using 100μgL⁻¹ of ¹³⁷Ba and ¹³⁶Ba over a 24h period returned a 100% mark-success rate in the otoliths of brown and rainbow trout at an estimated marking cost of $US 0.004 per fish. Larval immersion marks were clearly definable in the otoliths, with isotope ratios in marked fish 11 times greater than ratios measured in control fish. Furthermore, the process of marking was easy to apply, with <0.5% mortality during marking. We conclude that larval immersion marking is a suitable method for long-term monitoring of restocking success of hatchery-reared trout. If adopted, the method would enable hatcheries to cost effectively and accurately assess the real contribution of restocked fish to wild populations.
... In addition to responsibilities for restoration of species listed as threatened or endangered under the Endangered Species Act, the U.S. Fish and Wildlife Service (USFWS) is responsible for mitigating the effects of federal water improvement projects on fishing opportunities and produces substantial numbers of sport fish to be stocked and caught by anglers. In 2004, the USFWS stocked more than 40.5 million sport fish and 62.2 million salmon and steelhead (Halverson 2008). Recreational fishing supported by these federal programs is associated with $544 million in retail sales, $903 million in industry output, 13.5 million anglerdays, and more than 8,000 jobs (Charbonneau and Caudill 2010). ...
... The effect of state stocking programs on recreational fishing is substantially greater because of significantly larger stocking programs. In 2004, state agencies stocked nearly 1.39 billion sport fish and more than 230 million salmon and steelhead (Halverson 2008). ...
Article
Resource allocation for fisheries management and conservation in the United States has not grown substantially in recent years, and there is ongoing debate over how limited resources should be used to create, maintain, or restore fisheries. Hatcheries have been in existence in North America since 1848, but their organization and role in fisheries management are not widely understood or appreciated. The continuing debate about hatcheries has painted them in broad strokes, with critics suggesting that hatcheries are altogether ineffective, unnecessary, or too costly to operate or do more harm than good to wild populations. Such characterizations fail to articulate the diversity of hatchery operations and do not acknowledge the hatchery reform initiatives of the past 20 years or public expectations and legal requirements that influence the production and use of hatchery‐origin fish. In this paper, we describe the current number and distribution of fish hatcheries operated for public purposes in North America, provide insights on the costs and benefits of hatcheries operated for public use and other public trust purposes, provide initial cost comparisons to habitat rehabilitation or restoration, and consider the role of hatcheries into the future as a fisheries management tool. This article is protected by copyright. All rights reserved.
... Catchable-sized hatchery trout (hereafter, catchables) serve as an important component of many coldwater fisheries management programs throughout North America. In 2004 alone, nearly 60% of the ~80 million non-anadromous Rainbow Trout Oncorhynchus mykiss stocked by state and federal management agencies across the United States were released as catchables (>152 mm TL; Halverson 2008). While the overall number of trout stocked in the United States has declined since 1973, the total weight of stocked trout has increased (Halverson 2008), indicating that fisheries management agencies have shifted their stocking programs by providing anglers with fewer, larger trout. ...
... In 2004 alone, nearly 60% of the ~80 million non-anadromous Rainbow Trout Oncorhynchus mykiss stocked by state and federal management agencies across the United States were released as catchables (>152 mm TL; Halverson 2008). While the overall number of trout stocked in the United States has declined since 1973, the total weight of stocked trout has increased (Halverson 2008), indicating that fisheries management agencies have shifted their stocking programs by providing anglers with fewer, larger trout. Due to their size, catchables provide immediate fisheries once they are stocked and are especially important for coldwater fisheries that cannot support wild trout populations or where wild trout catch rates are low. ...
Article
Catchable‐sized hatchery trout (hereafter, catchables) have become a staple component of many fisheries management programs throughout North America. Due to their size, catchables create immediate fisheries once they are stocked, and fisheries managers have gradually shifted towards stocking fewer, larger trout. However, the cost of growing larger fish may reduce the efficiencies of catchable stocking programs overall. We grew catchable‐sized Rainbow Trout Oncorhynchus mykiss to two target average sizes (254 and 305 mm total length) at a production scale, while tracking feed expenditures to examine the costs and benefits associated with increased size‐at‐stocking. Although larger catchables cost 31% more in feed expenditures than those reared to a smaller average size, catch (by anglers) of larger fish increased by 100% relative to smaller fish. Consequently, if target stocking size was changed from 254 to 305 mm and feed costs were held constant by reducing the total number of fish stocked, anglers would benefit by catching larger and more fish, despite the reduction in number of fish stocked. In lentic systems, larger catchables were reported by anglers more quickly than smaller fish, so managers must consider interactions between stocking size and residence time for lentic systems supported by catchables. In lotic systems, overall catch by anglers was much lower than catch at lentic waterbodies, and all catchables were either reported by anglers quickly or failed to be reported at all regardless of size‐at‐stocking. Producing larger catchables for hatchery‐supported fisheries serves to benefit angling and would likely increase angler satisfaction while improving efficiencies associated with hatchery catchable stocking programs.
... By contrast, habitat enhancement activities were found to be the least prevalent management measures in German angling clubs (Fig. 2), used intensively by selected types of clubs only ( Table 1). The situation mirrors conditions in the USA (Halverson, 2008;Sass et al., 2017). ...
... In some German states, there are also public hatcheries (e.g., at Lake Constance), similar to those widespread in North America (Halverson, 2008). Some German angling clubs have also built their own hatcheries (Harisson et al., 2018). ...
Article
Social-ecological systems are characterized by interconnections between social (e.g., angler communities) and ecological systems (e.g., fish populations in lakes and rivers). One means by which human actions feedback on ecosystems is through management actions, some of which are controversial due to the possible downsides for biodiversity and ecosystem functioning. In complex systems, sub-optimal management strategies may become entrenched. In such cases, leverage points must be identified to escape undesirable stable states. Based on a review of published and grey literature about the management practice of fish stocking in German inland recreational fisheries, we describe key pathways characterizing social-ecological interactions and resulting outcomes. The pathways we review suggest that missing or dysfunctional information feedbacks predispose privately governed fisheries-management systems typical of Germany to develop stocking as a panacea in operational management. Similar outcomes are likely in open access recreational fisheries. Three key feedback cycles reinforce each other to maintain stocking in the manager's toolbox. The first is that the lack of dedicated monitoring in many fisheries and ignorance of research results breaks a feedback signal from the management measure of stocking to the evaluation of outcomes. The lack of ability of those involved in stocking to conclusively learn when stocking works and when it fails to deliver additive effects reinforces personal norms by managers and anglers that stocking may be necessary to sustain fisheries. A related second feedback is that stocking may increase catch rates in the short-term, which increases angler expectations for catch and stocking as a safeguard of the catch, in turn fostering linear cause-and-effect mental models and the emergence of a pro-stocking social norm among anglers. A third key feedback is among hatchery operators and fisheries managers in fishing clubs, where hatchery operators are often key informants about stocking practices while concurrently having commercial interests to sell fish for stocking. This creates economic incentives that perpetuate stocking. The amount of resource investments by angler communities through stocking is additionally fostered and maintained by monetary resource availability, size and type of ecosystem that is managed and governance processes as well as political inertia. Thus, the maintenance of stocking as a panacea is intimately linked to a range of psychological, social, economic and governance drivers. We use our case study to illustrate how information-related feedback loops can trap natural resource management strategies into a suboptimal basin of attraction, and provide recommendations on leverage points to possibly break these loops. Collaborative active adaptive management of natural resources and reducing the temptation to rely on economic incentives by hatcheries may be needed to introduce possibilities for learning and thereby avoid the entrenchment of stocking and related activities as a panacea. The lessons learned around stocking are applicable to a range of social-ecological issues in recreation and planning whenever feedback flows of information are critical to direct management and when these flows are either distorted by disinformation, wrong incentives or not present at all. Management Implications The study has several implications for fisheries and natural resource management: -Establishment of regular monitoring systems that are trusted by stakeholder can be recommended and is key to break dysfunctional information feedbacks and move social-ecological systems, such as recreational fisheries, on more sustainable trajectories. -Changing fish stocking under private fishing right systems can happen either through bottom-up approaches based on co-production of knowledge and using principles of adaptive management or from the top-down by implementing hard constraints on the possibility for self-organized stocking policies. -The former strategy will be more time-consuming and may fail in some situations, but is likely to create less conflicts and more durable outcomes from a social perspective. -Alternative to fish stocking, such as improvement of habitats or harvest constraints, should be considered whenever feasible.
... Brown trout are a keystone species within their natural range, have been translocated across the globe (Halverson, 2008;Hunt and Jones, 2018;Hasegawa, 2020), and have great socioeconomical value (Elliott, 1989;Liu et al., 2019). Because of their value and often high exploitation rates, restocking and stockenhancement are a common management practice for brown trout populations (Aas et al., 2018;Cucherousset et al., 2021). ...
... Restocking and stock enhancement is a taxonomically and geographically widespread. For conservation purposes, stocking is frequently done at larval or early juvenile stages (Halverson, 2008;Hunt and Jones, 2018), and a growing body of work provides evidence for sex-specific life histories in salmonid larvae and juveniles. We demonstrated that this is also true in the case in brown trout, with females starting sex differentiation earlier than males when raised under laboratory conditions. ...
Article
Full-text available
Salmonids are a socioeconomically and ecologically important group of fish that are often managed by stocking. Little is known about potential sex-specific effects of stocking, but recent studies found that the sexes differ in their stress tolerances already at late embryonic stage, i.e., before hatchery-born larvae are released into the wild and long before morphological gonad formation. It has also been speculated that sex-specific life histories can affect juvenile growth and mortality, and that a resulting sex-biassed demography can reduce population growth. Here we test whether juvenile brown trout (Salmo trutta) show sex-specific life histories and whether such sex effects differ in hatchery- and wild-born fish. We modified a genetic sexing protocol to reduce false assignment rates and used it to study the timing of sex differentiation in a laboratory setting, and in a large-scale field experiment to study growth and mortality of hatchery- and wild-born fish in different environments. We found no sex-specific mortality in any of the environments we studied. However, females started sex differentiation earlier than males, and while growth rates were similar in the laboratory, they differed significantly in the field depending on location and origin of fish. Overall, hatchery-born males grew larger than hatchery-born females while wild-born fish showed the reverse pattern. Whether males or females grew larger was location-specific. We conclude that juvenile brown trout show sex-specific growth that is affected by stocking and by other environmental factors that remain to be identified.
... Rainbow Trout (Oncorhynchus mykiss Walbaum) have been stocked on six continents for the creation of sport fisheries and are one of the most widely distributed invasives worldwide (MacCrimmon, 1971;Stankovic, Crivelli, & Snoj, 2015). In the United States alone, Halverson (2008) calculates State and Federal agencies released approximately 9.96 × 10 6 kg of Rainbow Trout in 2004. Despite the wide distribution and invasive nature of Rainbow Trout, little is known about its effects on the native fauna and flora, especially in North America. ...
Article
Full-text available
Due to widespread stocking, Rainbow Trout (Oncorhynchus mykiss Walbaum) are perhaps the most widely distributed invasive species in the world. Nonetheless, little is known about the effects of stocked Rainbow Trout on native non‐game species. We conducted experiments in an artificial stream to assess the effects of hatchery Rainbow Trout on home range and behaviour of Warpaint Shiners (Luxilus coccogenis Cope), a common minnow frequently found in stocked Southern Appalachian streams. We used the LoCoH algorithm to generate polygons describing the home ranges used by Warpaint Shiners. When a stocked trout was present Warpaint Shiners: (a) increased home range size by 57%, (b) were displaced into higher velocity mesohabitats, and (c) reduced mean overlap between the home ranges of individual warpaint shiners. Rainbow Trout did not significantly affect the edge/area ratio of Warpaint Shiner home ranges. Warpaint Shiner density (two and five fish treatments) did not significantly affect any response variable. Displacement from preferred microhabitats and increases in home range size likely result in increased energy expenditure and exposure to potential predators (i.e., decreased individual fitness) of Warpaint Shiners when stocked trout are present.
... Lotic trout (family Salmonidae) fisheries are among the most popular and valuable in the United States (USFWS and USCB 2011) but are also among the most dependent on hatcheries as a result of numerous factors, including loss of habitat from anthropogenic activities, overexploitation, and the popularity of and public demand for angling opportunities. Understanding the ecology and life history of hatchery-reared trout in natural environments was fundamental to assessing the efficacy of captive breeding and stocking programs (e.g., Needham andSlater 1944, 1945;Miller 1952Miller , 1953 and is increasingly necessary to manage fisheries as the reliance on stocking activities increases (Heidinger 1999;Halverson 2008;Trushenski et al. 2010). High mortality and low returns to the creel for stocked individuals resulted in early research on stocking larger fish as a management practice, and stockings of catchable-sized trout have been well documented to increase creel returns relative to smaller fish (Needham 1959;Cresswell 1981;Wiley et al. 1993a;Walters et al. 1997). ...
Article
Stream trout fisheries are among the most popular and valuable in the United States, but many are dependent on hatcheries to sustain fishing and harvest. Thus, understanding the ecology of hatchery‐reared trout stocked in natural environments is fundamental to management. We evaluated the growth, condition, and trophic relations of Brook Trout Salvelinus fontinalis, Brown Trout Salmo trutta, and Rainbow Trout Oncorhynchus mykiss that were stocked in southern Appalachian Mountain streams in western North Carolina. Stocked and wild (naturalized) trout were sampled over time (monthly; September 2012–June 2013) to compare condition and diet composition and to evaluate temporal dynamics of trophic position with stable isotope analysis. Relative weights (Wr) of stocked trout were inversely associated with their stream residence time but were consistently higher than those of wild trout. Weight loss of harvested stocked trout was similar among species and sizes, but fish stocked earlier lost more weight. Overall, 40% of 141 stomachs from stocked trout were empty compared to 15% of wild trout stomachs (N = 26). We identified a much higher rate of piscivory in wild trout (18 times that of stocked trout), and wild trout were 4.3 times more likely to consume gastropods relative to stocked trout. Hatchery‐reared trout were isotopically similar to co‐occurring wild fish for both δ13C and δ15N values but were less variable than wild trout. Differences in sulfur isotope ratios (δ34S) between wild and hatchery‐reared trout indicated that the diets of wild fish were enriched in δ34S relative to the diets of hatchery‐reared fish. Although hatchery‐reared trout consumed prey items similar to those of wild fish, differences in consumption or behavior (e.g., reduced feeding) may have resulted in lower condition and negative growth. These findings provide critical insight on the trophic dynamics of stocked trout and may assist in developing and enhancing stream trout fisheries.
... Rainbow trout (Oncorhynchus mykiss) is a commonly stocked species in the lakes and rivers of North America and around the world for the purposes of recreational fishing, enhancing natural populations, and commercial aquaculture production (Halverson 2008;Bailey and Sumaila 2012). Despite their widespread occurrence, both throughout their natural range and through stocking globally, there exists limited data on variation in seasonal and diel activity of rainbow trout in nature, especially without the effects of interspecific competition. ...
Article
Full-text available
The fine-scale behavioural activities of rainbow trout (Oncorhynchus mykiss) in nature are not well understood, but are of importance for identifying interactions with the ecosystem and of interest to conservationists and recreational anglers. We have undertaken a high-resolution acoustic telemetry study to identify the distinct movement patterns of 30 rainbow trout in a freshwater lake, specifically examining swim speed, area of movement, and site preference in both summer and winter. Activity levels were reduced in winter compared with summer across all fish, but ranking of individuals was consistent. In summer, 16/30 fish displayed diel movement, in which they travelled to a different area of the lake at dawn and returned at dusk, while other fish maintained their site preference regardless of the time of day or swam more randomly throughout the lake. These patterns were minimized in winter, where there was a reduction in cross-lake movement under ice and only 4/30 fish displayed diel movement. Winter conditions may limit the capability (physiological limitations) and (or) motivation (prey availability) for diel behaviours observed in summer.
... What are the most important problems arising from fish stocking? Stocking modifies aquatic ecosystems, changes nutrient cycles in lakes and causes population declines and a loss of genetic diversity (Cowx 1999;Halverson 2008). In Mexico, native and endemic freshwater fish have deteriorated because of basin degradation and introduction of exotic species (Alvarez-Torres et al. 2002). ...
Book
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Pursuing a multidisciplinary approach, this book highlights current challenges in, and potential solutions to, environmental water management in Mexico. It includes an essential review of current literature and state of the art research, providing a one-stop resource for researchers, graduate students and environmental water managers alike. The result of a cooperation between 35 researchers from seven Mexican academic institutions, two Federal Commissions and one international organization, the book links science to practice for living organisms and their environment, while also addressing anthropogenic effects on our water ecosystems. Particularly the book addresses the following subjects: Biodiversity in inland waters, physical and chemical characterization of inland waters, physico-chemical characterization of Mexican coastal lagoons, microbiota in brackish ecosystems, diversity associated with southern Mexico’s pacific coral reefs, fry fish stockings in aquatic epicontinental systems, a review of tuna fisheries in Mexico, fishery resource management challenges stemming from climate change, aquatic invasive alien species, harmful algal blooms, and aquatic protected areas, related ecological and social problems and the importance for fisheries’ yield.
... What are the most important problems arising from fish stocking? Stocking modifies aquatic ecosystems, changes nutrient cycles in lakes and causes population declines and a loss of genetic diversity (Cowx 1999;Halverson 2008). In Mexico, native and endemic freshwater fish have deteriorated because of basin degradation and introduction of exotic species (Alvarez-Torres et al. 2002). ...
Chapter
The proliferation of dams in Mexico between the 1940s and 1970s enabled the development of culture-based fisheries, especially those of exotic species, in order to increase the availability of cheap protein for the poorer social classes. This chapter describes the fishery policies and the stocking situation over the last 15 years for seven geo-economic regions, as well as from 1974 to 2013 on a national scale, based on official information provided by the Mexican government (Federal Fisheries Agency, National Commission on Aquaculture and Fisheries, CONAPESCA). The present fishery production in Mexico accounts for c. 1.7 million tonnes/year, of which 10.3% is derived from inland waters. Up to 2003, most of this production (±85%) corresponded to fisheries based on fish stocking. However, this trend changed over the last decade, and at present, the production of intensive systems is almost equal to extensive systems. Intensive systems increased production over the past 5 years, and in 2014, their production is close to extensive systems. This change is the result of the government policies of the last administrations in Mexico, and it took place without a formal cost/benefit analysis of fish stocking. Under this scenario, we mean to respond to the following questions: What species have been used in stocking freshwater areas in Mexico? Is fish stocking related to yield? What are the strategies the Mexican government has followed for fisheries based on fish stocking? What is the general tendency of fisheries based on fish stocking in Mexico?
... Inland freshwater food webs have been particularly influenced by species invasions (Welcomme 1992) due to prevalent intentional and unintentional stocking of forage and game fish species (Gozlan 2008;Halverson 2008;Gozlan et al. 2010). The White Perch Morone americana is an originally anadromous species that is native to the Atlantic coast of North America, which has greatly expanded its range inland over the past three decades (Boileau 1985;Feiner et al. 2012). ...
Article
The detrimental impacts of invasive species often occur through deleterious trophic interactions (e.g., competition) with native species. However, the potential for competitive interactions between species may vary among systems, seasons, or throughout species’ ontogeny, requiring a thorough examination of trophic niches to determine whether overlap exists, and elucidate the likelihood of competition. Black Crappie Pomoxis nigromaculatus is a popular game fish species across the United States, but recent invasions of White Perch Morone americana, which exploit a similar trophic niche, into southern reservoirs represent a major concern for the continued sustainability of Black Crappie fisheries. We examined the trophic niches of these species throughout their ontogeny in two North Carolina reservoirs in 2009 and 2010 using a combination of diet content and stable isotope analyses. Extensive and significant similarities in diet composition and isotopic niche overlap existed between Black Crappie and White Perch throughout their ontogeny and across seasons in both systems. Overlap was particularly high between smaller (<200 mm), invertivorous Black Crappie and all sizes of White Perch. This overlap suggests that, should invertebrate resources be limited, competition during the juvenile stage could reduce growth rates and survival of young Black Crappie. By evaluating variation in the trophic niches of each species among seasons, body sizes, and reservoirs, we conclude that the potential for competitive interactions between White Perch and Black Crappie is high in southern reservoirs. Management options to either reduce White Perch abundance or prevent their spread to novel habitats may be necessary to sustain native and supplemented Black Crappie populations that are potentially vulnerable to White Perch invasions. This article is protected by copyright. All rights reserved.
... The benefits from stocking large fish in both naturally reproducing and non-reproducing situations that we found in our model are generally consistent with other models , Camp et al. 2014) and empirical studies (e.g., Wiley et al. 1993, Yule et al. 2000, Meyer et al. 2012. Our model supports the trend seen in some countries to stock increasingly larger fish including catchable fish in stock-enhancement efforts (Halverson 2008), which is likely a response to fry and small fingerlings rarely producing sustained outcomes for ecological reasons. However, the more successful stock-enhancement efforts in naturally reproducing stocks become, the more likely these efforts are to replace the wildstock component (Rogers et al. 2010, van Poorten et al. 2011, and potentially increase angling impacts by attracting increased fishing pressure (Baer et al. 2007), thereby creating a fundamental trade-off among fisheries benefits and conservation (Amoroso et al. 2017. ...
Article
Fish stocking and harvest regulations are frequently used to maintain or enhance freshwater recreational fisheries and contribute to fish conservation. However, their relative effectiveness has rarely been systematically evaluated using quantitative models that account for key size‐ and density‐dependent ecological processes, and adaptive responses of anglers. We present a new integrated model of freshwater recreational fisheries where the population dynamics of two model species affect the effort dynamics of recreational anglers. With this model we examined how stocking various fish densities and sizes (fry, fingerlings, and adults) performed relative to minimum‐length limits using a variety of biological, social and economic performance measures, while evaluating trade‐offs. Four key findings are highlighted. First, stocking often augmented the exploited fish population, but size‐ and density‐dependent bottlenecks limited the number of fry and fingerlings surviving to a catchable size in self‐sustaining populations. The greatest enhancement of the catchable fish population occurred when large fish that escaped early bottlenecks were stocked, but this came at the cost of wild‐stock replacement, thereby demonstrating a fundamental trade‐off between fisheries benefits and conservation. Second, the relative performance of stocking naturally reproducing populations was largely independent of habitat quality and was generally low. Third, stocking was only economically advisable when natural reproduction was impaired or absent, stocking rates were low, and enough anglers benefitted from stocking to offset the associated costs. Fourth, in self‐sustaining fish populations, minimum‐length limits generally outperformed stocking when judged against a range of biological, social and economic objectives. By contrast, stocking in culture‐based fisheries often generated substantial benefits. Collectively, our study demonstrates that size‐ and density‐dependent processes, and broadly the degree of natural recruitment, drive the biological, social and economic outcomes of popular management actions in recreational fisheries. To evaluate these outcomes and the resulting trade‐offs, integrated fisheries‐management models that explicitly consider the feedbacks among ecological and social processes are needed. This article is protected by copyright. All rights reserved.
... Poor recruitment and overfishing may be mitigated by implementing a stocking program to improve recreational fisheries by restoring or enhancing natural populations (Kerr 2011). Collectively, these programs stock millions of Sauger; for instance, in 2004 nearly 28 million Sauger were stocked in the US (Halverson 2008). However, due to the high costs associated with any stocking program, it is imperative to assess stocking success by observing the contribution of hatcheryraised fish to the wild population. ...
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Sander canadensis (Sauger) once supported a viable fishery in many of the reservoirs throughout Tennessee; however, these populations have experienced widespread declines. To improve population numbers, the Tennessee Wildlife Resources Agency began stocking Sauger in 1992 in Tennessee and Cumberland river impoundments. Here we examine the percent contribution of hatchery-stocked Sauger to the wild population in Old Hickory Lake, a mainstem impoundment on the Cumberland River. We determined the contribution of hatchery-stocked Sauger using microsatellite markers and a categorical allocation-based parentage analysis. We also evaluated measures of genetic diversity, including estimates of heterozygosity and effective population size. Genetic variation was comparable to other stocked populations of percids. However, estimates of effective population size were low and the contribution of hatchery-reared Sauger to natural populations was moderate, averaging 25.8% across sampled year classes. Despite high genetic diversity, the Sauger population in Old Hickory Lake may be declining, and hatchery efforts to supplement Sauger numbers are contributing little to recovery of the population.
... In contrast, freshwater resident populations, commonly referred to as rainbow trout, are not protected, even though many populations are native and have lost anadromy due to human habitat alteration (Clemento, Anderson, Boughton, Girman, & Garza, 2009). In an ironic twist of fate, freshwater resident rainbow trout has become the most widely distributed freshwater fish in the world due to human introductions, and these invasive rainbow trout originate largely from California hatchery stocks (Crawford & Muir, 2008;Halverson, 2008;Stanković, Crivelli, & Snoj, 2015). ...
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Human-driven evolution can impact the ecological role and conservation value of impacted populations. Most evolutionary restoration approaches focus on manipulating gene flow, but an alternative approach is to manipulate the selection regime to restore historic or desired trait values. Here we examined the potential utility of this approach to restore anadromous migratory behavior in coastal California steelhead trout (Oncorhynchus mykiss) populations. We evaluated the effects of natural and anthropogenic environmental variables on the observed frequency of alleles at a genomic marker tightly associated with migratory behavior across 39 steelhead populations from across California, USA. We then modeled the potential for evolutionary restoration at sites that have been impacted by anthropogenic barriers. We found that complete barriers such as dams are associated with major reductions in the frequency of anadromy-associated alleles. The removal of dams is therefore expected to restore anadromy significantly. Interestingly, accumulations of large numbers of partial barriers (passable under at least some flow conditions) were also associated with significant reductions in migratory allele frequencies. Restoration involving the removal of partial barriers could be evaluated alongside dam removal and fishway construction as a cost-effective tool to restore anadromous fish migrations. Results encourage broader consideration of in situ evolution during the development of habitat restoration projects. This article is protected by copyright. All rights reserved.
... Numerous state and provincial agencies in North America use hatchery trout as a means to create or enhance fisheries, stocking either fingerlings for put-and-grow fisheries or catchable-sized trout for putand-take fisheries. Over time, many agencies have gradually stocked fewer fingerling trout, switching their production largely to catchablesized fish (Cresswell, 1981;Halverson, 2008), because larger trout survive better and return to creel at higher rates (Leitritz, 1970;Wiley et al., 1993;Yule et al., 2000) than do smaller trout. Catchable-sized hatchery trout (herein, catchables) have become an important component of many fisheries management programs in coldwater habitats, because they provide instantaneous fisheries once they are stocked. ...
... Additionally, some invasive species which are valuable for recreation purposes (i.e., hunting and fishing) are moved into new locations to augment or create new populations for recreation. For example, rainbow trout are often moved into new watersheds to support the fishing industry 6 , and ungulates are moved across county, state, and national borders for hunting 7,8 . Sometimes these introductions are not conducted by management agencies, but by individuals acting illegally 9 . ...
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Population dynamics of species that are recently introduced into a new area, e.g., invasive species and species of conservation concern that are translocated to support global populations, are likely to be dominated by short-term, transient effects. Wild pigs (Sus scrofa, or wild boar) are pulsed-resource consumers of mast nuts that are commonly introduced into new areas. We used vital rate data (i.e., survival and fecundity) for wild pigs in Germany under varying forage conditions to simulate transient population dynamics in the 10-years following introduction into a new environment. In a low forage environment (i.e., conditions similar to their native range), simulated wild pig populations maintained a stable population size with low probability of establishment, while in environments with better quality forage (i.e., conditions similar to parts of their invasive range), high juvenile fecundity and survival facilitated rapid population growth and establishment probability was high. We identified a strategy for simulating population dynamics of species whose reproduction and survival depend on environmental conditions that fluctuate and for predicting establishment success of species introduced into a new environment. Our approach can also be useful in projecting near-term transient population dynamics for many conservation and management applications.
... The popularity of Walleye has resulted in situations where demand exceeds supply, which has led to the development and implementation of stocking programs across the USA and Canada to establish new populations and supplement current populations (Barton 2011). In 2004, U.S. Walleye stockings were nearly 1.1 × 10 9 (Halverson 2008). However, Walleye stocking programs can have highly variable stocking success (Kerr 2007) that can result in weak year-classes (Willis and Stephen 1987;Johnson et al. 1996;Nate et al. 2000). ...
Article
Age‐0 Walleye Sander vitreus are stocked to achieve several management objectives. However, stocked Walleye are exposed to numerous handling‐ and transport‐related stressors that can negatively influence disease resistance, survival, year‐class strength, and fisheries management objectives. The objective of this study was to evaluate relationships between Walleye transport duration with changes in water chemistry, whole‐blood glucose and plasma cortisol concentrations, and short‐term (48‐h) mortality. Walleye were transported between 3.5 and 6.0 h and stocked into holding cages located at one of seven sites. Water quality and stress (via whole‐blood glucose and plasma cortisol) and mortality were evaluated prior to, during, and at 0, 2, 24, and 48 h posttransportation. During transport, water temperatures generally decreased, while carbon dioxide concentrations fluctuated between 2.7 and 22.5 mg/L. Walleye whole‐blood glucose and plasma cortisol concentrations varied by site and time since transport. Changes in carbon dioxide concentrations were associated with changes in whole‐blood glucose concentrations. However, cumulative survival rates and plasma cortisol concentrations were not associated with water quality or transportation duration. Understanding Walleye tolerance to transportation‐induced stress has the potential to enhance stocking programs by providing the opportunity for managers to make informed transport decisions.
... Fish are stocked in freshwater and marine systems worldwide with the aim of reintroducing or re-establishing species to restore aquatic environments to a more natural state and create recreational and commercial fishing opportunities (Hol c ık 1991; Halverson 2008). The issue with stocking remains that we are often unaware of the fates of these fish after stocking due to difficulty in monitoring them. ...
Article
Telemetry studies often assume the lack of adverse effects caused by tag attachment and presence in various species and size classes, which may lead to inaccurate conclusions about fish behaviour in field studies. Studies that examine the effects of tagging are typically performed on salmonids and adult fishes rather than the small fishes that are becoming increasingly the focus of telemetry studies. The objectives of this study were to assess the effects of intracoelomic acoustic tagging on growth, condition, survival, and tag retention in sub‐adult hatchery Bloaters Coregonus hoyi (a focal species for restoration efforts in the Laurentian Great Lakes) and to determine the maximum tag burden below which tag effects are reduced. Fish were either tagged with one of three dummy acoustic transmitters (Vemco: V6, n = 50; V7, n = 50; V9, n = 50) or were followed as controls (n = 50, anaesthesia, PIT tag and handling only) and sham individuals (n = 49, anaesthesia, surgery, suturing and PIT tags but no tag implanted). Tags represented 1.3 to 9.0% of body mass. All fish were tagged with a passive integrated transponder (PIT) tag for individual identification throughout the 6‐month (November 2014 – May 2015) monitoring period. Survival exceeded 90% in all treatment groups and tag retention rate was 100%. All surviving fish appeared healthy and in excellent condition at the conclusion of the experiment. The results of this study suggest that sub‐adult Bloater, a small laterally compressed pelagic fish, can successfully be implanted intracoelomically with acoustic transmitters of ≤9% tag to body mass ratio with no adverse effects. This article is protected by copyright. All rights reserved.
... In recreational fisheries, releases of hatchery-reared fish can augment naturally recruiting populations (Bell et al., 2006), improve angler catch rates and provide a range of socioeconomic benefits in theory (Camp et al., 2014). Freshwater fisheries enhancements have been well established in fisheries management and often comprise a substantial fraction of management budgets (Johnson et al., 1995;Ross and Loomis, 1999;Loomis and Ng, 2012;Patterson and Sullivan, 2013;US DOI, 2016), perhaps due to its popularity among stakeholders (Halverson, 2008). Past enhancement attempts in freshwater and marine systems, however, have largely failed to meet fisheries objectives and often have unintended ecological or genetic impacts on wild populations (Hilborn and Eggers, 2000;Leber, 2002;Tringali et al., 2008;Lorenzen, 2014). ...
... In addition to raising fish that are directly marketed for human consumption, many aquaculture facilities produce fish that are used to support stocking efforts in public and private fisheries. In 2004, the US government had stocked 1.75 billion fish of 104 species throughout the waters of the USA (Halverson 2008). In aquaculture facilities, increased stocking density can lead to amplification of parasite life cycles (Born-Torrijos et al. 2016). ...
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Digenean trematodes have complex life cycles and control of these flatworms can be accomplished by eliminating immature parasite stages from intermediate hosts. In aquaculture systems, presence of trematode metacercariae can negatively impact fish health and lead to economic losses. Posthodiplostomum minimum is a parasite of birds that uses bluegill sunfish (Lepomis macrochirus) as the intermediate host and is commonly found in fish used to stock waterways for recreational purposes. In this study, we evaluated killing of P. minimum metacercariae by injectable praziquantel in naturally infected bluegills. Using propidium iodide staining and motility assessment, we found that 5 mg/kg administered intramuscularly was effective for parasite killing. However, metacercarial death was not apparent until day 7 post-treatment. Our results demonstrated that propidium iodide staining is an effective method for detecting death in metacercariae recovered from treated fish. This method was at least as sensitive as objective motility scoring and provided quantitative assessment of parasite death. Future studies involving treatment of metacercariae in fish with praziquantel may need to be carried out over a period of weeks in order to accurately assess parasite killing and would benefit from using the propidium iodide method.
... hatcheries), with limited genetic input from wild populations (Bilio, 2007;Teletchea and Fontaine, 2012). Captive propagation and release programs are commonly operated with the intent to bolster declining wild populations (Araki and Schmid, 2010;Brown and Day, 2002), support commercial or sport-fishing activities (Halverson, 2008), or produce fish for biological control of pest species (Chandra et al., 2008;Swanson et al., 1996). Growing focus has been given to whether captive-propagated fish provide the socio-economic or ecological services associated with wild fish (Ham and Pearsons, 2001;Pearsons and Hopley, 1999;Pister, 2001). ...
Article
Trophic interactions are an enduring framework for ecological thought. Broad and growing evidence for contemporary evolution has demonstrated that ecology and evolution dynamically interact on similar time scales. In this dissertation, I seek to understand how genetic and plastic trait change in human-influenced systems shape trophic dynamics, how such trait changes are constrained by inherent tradeoffs, and the broad implications of such trait change for ecological communities. I advance the premise that competition-defense tradeoffs are the essential mechanism behind many eco-evolutionary trophic dynamics that can reshape multi-trophic communities. In support of this view, I assess the presence of ecologically relevant genetic evolution along a competition-defense tradeoff in a model species. I also employ models and experiments to quantify how the particularly strong genetic and plastic trait changes in population phenotypes generated by humans can rearrange ecological communities by altering trophic interaction strengths.
... Instead, marine fish stocking is heavily focused on species that are either of commercial or recreational value or both (Bartley and Bell, 2008;Taylor et al., 2017;Kitada, 2018). Marine fisheries stock enhancement has been implemented for numerous species such as crabs, eels, salmon prawns and sharks (Feunteun, 2002;Halverson, 2008;Pratt and Threader, 2011;Lee et al., 2015;Taylor, 2017). The restocking of marine species that are listed as 'threatened species', through either translocation or release from breeding programs, is seldom done; however, there are some examples of restocking for threatened marine invertebrates (Baldacconi et al., 2010;Rogers-Bennett et al., 2016;Cabaitan and Conaco, 2017). ...
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The White’s seahorse Hippocampus whitei was listed as an Endangered species in 2020 on Australian state and federal legislation, as a result of population declines across its range attributed to habitat loss over the past decade. A captive-bred reintroduction program has been implemented as a possible management tool for species recovery, however, the viability of such a reintroduction program for seahorses has not been assessed to date. This study implemented a pilot captive-breeding program using adult H. whitei from Sydney Harbour, Australia, as brood stock. A total of 90 captive-bred seahorses were released into the wild on two different artificial habitat types (“seahorse hotels” and protective swimming net). Following release, a monthly post-release monitoring program was implemented for 12 months that involved underwater visual census surveys of the tagged seahorses. Sightings of captive-bred seahorse numbers were found to gradually decline over the 12-month period, with fewer seahorses found on the swimming net compared to the seahorse hotels and higher resighting probability of captive-bred animals on the seahorse hotels. After 12 months, 20% of the captive-bred seahorses were detected on the seahorse hotels, whilst two individuals were still observed 18 months after release on the hotels. Only 2% of captive-bred seahorses were observed on the swimming net after 12 months, with two individuals still detected on the net after two years. Nine of the captive-bred seahorses were found to reproduce in the wild, with two individuals observed mating with the wild population. This pilot study indicates that captive-bred seahorses can survive for up to two years in the wild, as well as contribute to local population recovery through reproductive success. However, while conservation stocking shows promise as a potential management tool to assist with threatened seahorse species recovery, there are several factors such as existing threats to the species that need to be addressed before such a program is implemented.
... Fish stocking is a fisheries management tool that particularly requires cost-effectiveness evaluation, due to its common application and heavy investment both economically and socially. Economic investment is seen in the large sums of often public money used to annually stock billions of fish worldwide (Welcomme and Bartley, 1998;Halverson, 2008;Lorenzen, 2014). In some cases, stocking programs are reported to constitute the http://dx.doi.org/10.1016/j.fishres.2016.09.003 0165-7836/© 2016 Elsevier B.V. All rights reserved. ...
... Currently, many stocking programs worldwide focus on the total number of individuals that are released into waterways every year (Halverson 2008; Victorian Fisheries Authority 2020), rather than specific attributes of the fish and the environmental conditions at the stocking locations. The present study emphasises that there should also be a focus on producing individuals that have the highest chance of surviving. ...
Article
Stock enhancement is an important tool used to rebuild depleted fish populations or enhance recreational fishing. Hatchery-reared individuals can express trait differences, such as growth, which may affect later survival. However, there is little understanding of how early life growth variation affects stocking success. We examined early life growth of golden perch Macquaria ambigua and assessed how growth within hatcheries affects the survival of stocked fish. We measured daily otolith increment widths at 10, 20 and 30 days after hatching, but before stocking into lakes in south-eastern Australia. Mean growth decreased with age, but variation in growth increased. We then compared the early life growth of these individuals to those recaptured after 2 years at liberty (age-2+). Faster individual growth between 20 and 30 days was positively correlated with increased length at stocking. Mean growth between 20 and 30 days of age-2+ fish was higher than that of young-of-year fish, but among-individual variation in growth did not differ between the two groups. These results suggest that individuals with fast hatchery growth have increased survival to 2 years. We propose that enhancing growth within hatcheries may increase the survival of stocked fish, and thus the cost-effectiveness of fish stocking.
... Working with tribes, lake associations, angler groups, and stake- (WDNR, 2020). Developing accept or direct strategies, like changing regulations for warmwater species to promote those fisheries or implementing habitat projects that maintain ecosystem function, will have to overcome the investments in fish hatchery infrastructure, the loss of aquaculture jobs, and long-held assumptions that stocking can overcome ecosystem deficiencies to provide desirable fishing opportunities (Halverson, 2008;Sass et al., 2014Sass et al., , 2017. ...
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Decision-makers in inland fisheries management must balance ecologically and socially palatable objectives for ecosystem services within financial or physical constraints. Climate change has transformed the potential range of ecosystem services available. The Resist-Accept-Direct (RAD) framework offers a foundation for responding to climate-induced ecosystem modification; however, ecosystem trajectories and current practices must be understood to improve future decisions. Using Wisconsin’s diverse inland fisheries as a case study, management strategies for recreational and subsistence fisheries in response to climate change were reviewed within the RAD framework. Current strategies largely focus on resist actions, while future strategies may need to shift toward accept or direct actions. A participatory adaptive management framework and co-production of policies between state and tribal agencies could prioritize lakes for appropriate management action, with the goal of providing a landscape of diverse fishing opportunities. This knowledge co-production represents a process of social learning requiring substantial investments of funding and time.
... Fish stocking is among the most ubiquitous management strategies in North America and globally (e.g., Halverson 2008;Lorenzen et al. 2012;Lorenzen 2014). Like many other jurisdictions, the state of Michigan has a long history of fish stocking and currently stocks numerous species across hundreds of sites throughout the state. ...
Article
Evaluation of fisheries management actions are critical but can be challenging when management actions are applied at broad spatial scales. Likewise, evaluations can be limited if monitoring data are not available for comparison. One widely applied management strategy that can be difficult to evaluate at broad spatial scales is the stocking of fish. We used presence/absence data collected by 209 surveys of the Michigan Stream Status and Trends Program, a standardized statewide stream monitoring project, for Brown Trout Salmo trutta over 20.3 cm total length and landscape‐scale site predictor variables to generate a random forest model of Brown Trout presence or absence. The model had an overall error rate of 19% and was used to predict the presence and absence of Brown Trout in all Michigan stream segments (n = 68,123 stream segments). We evaluated model predictions using an independent data set containing 773 validation surveys. Validation surveys where Brown Trout were predicted present had catch rates 30% higher than validation surveys occurring at sites where Brown Trout were predicted absent, indicating biological relevance of model predictions. Comparisons with model predictions and recent Brown Trout stocking sites revealed that since 2002 Michigan has stocked nearly 9 million Brown Trout in streams our classification model predicted to be absent of Brown Trout over 20.3 cm, suggesting that field evaluation of those sites may be warranted to avoid ineffective use of resources. The model we developed can be used as a screening tool to identify the potential suitability of future stocking sites and prioritize existing stocking sites for field validation surveys to ensure efficient deployment of agency resources.
... These results may reflect inlandcoastal and western-southern differences in meanings of, and contexts for, aquaculture and corresponding variability in how respondents perceived Step 9 ("Make aquaculture an important ally"). Aquaculture has a long history in inland fisheries management through hatchery-based stocking programs (e.g., black bass, trout; Table 1), particularly those that are operated by state freshwater fisheries agencies (Halverson 2008), which may help explain inland-coastal differences observed herein. Aquaculture also has a rich history in the southern USA, where it may already be viewed as a central component of fisheries management (i.e., it has already been "made an ally"), or it may be viewed as an agricultural practice separate from fisheries management. ...
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(read-only version: https://onlinelibrary.wiley.com/share/author/5KWZUPEPKC4RUVWP2YCS?target=10.1002/fsh.10695) The Ten Steps to Responsible Inland Fisheries are global recommendations to address the subordinate position of inland fisheries in sustainability dialogues. Regional and local perspectives are essential for implementing global initiatives. Hence, we surveyed state fisheries agency administrators and American Fisheries Society Governing Board members about the importance, funding, and achievability of the Steps. Respondents rated Science, Communication, and Assessment as highly important, well funded, and achievable steps, unlike Aquaculture and a global Action Plan. Nutrition was rated the most inadequately supported yet achievable step, highlighting an opportunity to promote nutritional contributions of inland fisheries. Opinions were similar between administrators and Governing Board members across U.S. regions, suggesting a foundation for incorporating underemphasized steps into management programs by building multi-organizational partnerships and applying lessons from better integrated steps (e.g., Science, Assessment). Overall, the Steps can advance freshwater science and management in the United States while increasing the visibility of inland fisheries that are rarely prioritized globally.
... Another example is the escape of captive organisms from aquaculture. Intentional introductions may be done within a legal framework, such as governmental stocking of fisheries species (Halverson, 2008) or biocontrol agents (Pipalova, 2006) or outside of a legal framework, such as aquarium or pet release (Padilla & Williams, 2004), sportfish release by anglers (Rahel, 2004) or ceremonial release (Magellan, 2019). There is a strong link between human activity and the number and extent of non-native species colonizations (Calderon-Aguilera et al., 2012). ...
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Biodiverse and productive, tropical wetlands sustain large human populations globally. However, the extent of their use makes them vulnerable to introductions of nonnative species. Whether intentional or accidental these introduced species have the potential to become invasive and cause significant biotic change through mechanisms including competition, predation, hybridization, disease transmission, and ecosystem engineering. The societal impacts of invasive species can be similarly extensive, including loss of amenity, income and damage to health. Tropical wetland invaders take many forms, and some of the most damaging include plants: water hyacinth Eichhornia crassipes, giant salvinia Salvinia molesta, and melaleuca tree Melaleuca quinquenervia; invertebrates: golden apple snail Pomacea canaliculata, red swamp crayfish Procambarus clarkii and Australian redclaw crayfish Cherax quadricarinatus; and vertebrates: Nile tilapia Oreochromis niloticus, cane toad Rhinella marina, and Burmese python Python bivittatus. These examples exhibit a wide range of impacts and warrant diverse management options to control them, with varying outcomes. In large wetland systems, biological invasions often interact alongside a number of other anthropogenic impacts. Using three wetland case studies—the Greater Everglades Ecosystem (GEE) in North America, Kafue Flats in Africa, and the Lower Mekong Basin (LMB) in Asia—we illustrate the cost and complexity of invasion biology and management at this scale.
... Supplemental stocking is one of the most ubiquitous fisheries management strategies in North America (Halverson 2008). This approach is commonly used to mitigate anthropogenic disturbances (e.g., dams, overharvest, habitat degradation) by artificially increasing the abundance of recreationally or commercially valuable species (Jackson et al. 2004). ...
Article
Brook Trout Salvelinus fontinalis have faced significant declines throughout their native range and have been stocked in Midwestern waters since the late 1800s to offset such losses. Several studies have investigated the genetic effects of these stockings, but these efforts have been confined to relatively small spatial scales. In this study, we compiled 8,454 Brook Trout microsatellite genotypes from 188 wild Midwestern populations and 26 hatchery strains to provide novel insights of broadscale population structure, regional patterns of genetic diversity, and estimates of hatchery introgression for inland Wisconsin populations. Our results indicate high levels of differentiation among our study populations, a lack of hydrological population structuring, lower estimates of genetic diversity in the Driftless Area, and that hatchery introgression has been largely confined to regions of inland Wisconsin that have been heavily affected by anthropogenic disturbances (i.e., the Driftless Area). We also provide evidence that populations may be able to purge hatchery‐derived alleles, discuss possible mechanisms behind this phenomenon, and consider their relevance to accurate estimation of hatchery introgression. Collectively, these results summarize the genetic effects of over a century of anthropogenic disturbance on native Brook Trout populations and emphasize the importance of integrating historical data into contemporary genetic research of intensively managed species.
... Many fisheries have also introduced restocking efforts, where fish or shellfish are raised in aquaculture environments from eggs to juvenile life stages, and then released into the wild (reviewed in e.g. Halverson 2008;Taylor et al. 2017). In order to distinguish hatchery-reared individuals from wild ones in later life stages, a variety of different methods have been used, including different types of staining (Camp et al. 2013) and electronic tags (Nzau Matondo et al. 2019). ...
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The European lobster ( Homarus gammarus ) forms the base of an important fishery along the coasts of Europe. However, stocks have been in decline for many years, prompting new regulations in the fishery and also restocking efforts. An important feature of any restocking effort is the assessment of success in the number of released juveniles that stay and become adult over time. Here, we tested the power of a single nucleotide polymorphism (SNP) DNA marker panel developed for population assignment to correctly infer parentage on the maternal side of lobster larvae, in the absence of known fathers, using lobsters included in a current restocking effort on the Swedish west coast. We also examined the power to reconstruct the unknown paternal genotypes, and examined the number of fathers for each larval clutch. We found that the 96-SNP panel, despite only containing 78 informative markers, allowed us to assign all larvae to the correct mother. Furthermore, with ten genotyped larvae or more, confident paternal genotypes could be reconstructed. We also found that 15 out of 17 clutches were full siblings, whereas two clutches had two fathers. To our knowledge, this is the first time a SNP panel of this size has been used to assess parentage in a crustacean restocking effort. Our conclusion is that the panel works well, and that it could be an important tool for the assessment of restocking success of H . gammarus in the future.
... The U.S. aquaculture industry produces approximately 5,634 metric tons of hybrid Striped Bass annually (USDA 2013), most of which are sold in live markets or whole on ice. State and federal hatcheries produce an additional 25 metric tons of hybrid Striped Bass annually for stocking into public waters (Halverson 2008), and there are reportedly 17 private farms that produce hybrid Striped Bass for the express purpose of supporting recreational fishing (USDA 2013). Per Kohler (2004), the production of hybrid Striped Bass as a food fish and sport fish is one of the fastest growing segments of U.S. aquaculture. ...
Article
Understanding fatty acid requirements in multiple taxa is necessary to determine the degree to which dietary fish oil can be reduced or replaced with less costly, more abundant lipid sources. The polyunsaturated fatty acid (PUFA) requirements of hybrid Striped Bass Morone chrysops × M. saxatilis are currently reported as 0.5‐1.0% EPA (eicosapentaenoic acid, 20:5n‐3) and/or DHA (docosahexaenoic acid, 22:6n‐3). This requirement does not account for n‐3 PUFA essentiality on an individual fatty acid basis and does not address possible requirements for n‐6 PUFA, i.e., linoleic acid (18:2n‐6) or ARA (arachidonic acid; 20:4n‐6). Accordingly, hybrid Striped Bass were fed diets containing selected individual n‐3 and n‐6 C18 polyunsaturated fatty acids (C18 PUFA), n‐3 and n‐6 long chained polyunsaturated fatty acids (LC‐PUFA), or combinations thereof to determine the essentiality or expendability of these nutrients. These experimental feeds were compared to feeds containing only saturated fatty acids (negative control) or menhaden fish oil (positive control). Growth performance and ratios of 22:5n‐6 : 22:6n‐3 observed in tissue fatty acid profiles suggested dietary provision of 22:6n‐3 was adequate to satisfy physiological demand for LC‐PUFA. However, reductions in FCR and numeric improvements in growth suggest dietary provision of 20:4n‐6 is also important. Results of this study indicate provision of C18 PUFA alone is insufficient to avoid essential fatty acid deficiency and support optimal growth of this fish. To ensure essential fatty acid requirements are met and performance is optimized, diets for hybrid Striped Bass should be formulated to contain 22:6n‐3 and 20:4n‐6, if not a full complement of n‐3 and n‐6 LC‐PUFA.
... For example, fish stocking began in the United States in the mid-1800s and was central to the strategy of the U.S. Fish Commission, which was established in 1871 (Pister 2001). Though controversial (Cowx 1994), stocking has remained an important component of U.S. freshwater fisheries management, where it is implemented largely by state agencies (Halverson 2008) and is used to subsidize recreational fisheries and rehabilitate endangered or threatened fish populations. By contrast, marine stock enhancement has been rare and more controversial (Grimes 1998;Hilborn 1998): Red Drum Sciaenops ocellatus is the only fully marine species with a stock enhancement program in the USA (implemented by state agencies in Texas, Florida, and South Carolina). ...
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Ecosystem‐based fisheries management (EBFM) is an application of ecosystem‐based management in which abiotic, biotic, and socio‐economic interactions are considered when managing fisheries. The primary objectives of this study were: (1) to understand how state fishery scientists define EBFM; (2) to identify the perceived implementation of EBFM components within state agencies; and (3) to identify potential barriers in implementing EBFM at the state level. The uniformity across inclusion responses indicated that there was a shared definition of EBFM among state fishery scientists. The most frequently implemented component was engaging stakeholders, and the least frequently implemented component was accounting for uncertainty in ecosystems. Overall, the most frequently cited barriers were stakeholder engagement in the New England region and regulatory barriers in the mid‐Atlantic region. These findings can help identify where potential human and fiscal resources should be allocated for successful implementation of EBFM at the state level.
... Walleye have historically been or are currently stocked in a majority of states and provinces in North America, with recent estimates of 700 million to 1 billion walleye stocked on an annual basis (Fenton et al. 1996, Halverson 2008, Kerr 2008. Despite extensive stocking efforts, stocking success of walleye is highly variable and relatively unpredictable among systems and years (Ellison andFranzin 1992, Jennings et al. 2005). ...
Article
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Walleye (Sander vitreus) occur naturally or through extensive introductions in many inland lakes (i.e., non-Laurentian Great Lakes) throughout North Central North America. Persistence of walleye in these systems is influenced by factors including habitat, species interactions, exploitation, and stocking. Managers have expressed concerns about recent declining walleye recruitment and abundance in many inland populations, despite various conservation efforts (e.g., stocking, regulations). Therefore, we synthesized the scientific literature to provide information on how habitat influences successful natural recruitment and stocking. Historical and more recent studies indicate walleye are most successful in coolwater, mesotrophic, intermediate-to-large (>100 ha) lakes and that they spawn close to shore, in shallow water, and predominately over gravel and cobble substrates. Recent studies suggest that age-0 recruitment bottlenecks are likely occurring between hatching and midsummer. Relatedly, survival of stocked walleye tends to be higher for large fingerlings over fry or small fingerlings. Modeling studies indicate walleye declines may be attributed to warmer water and increasing water clarity, especially in smaller lakes or those with higher Centrarchidae or northern pike (Esox lucius) abundance. Important future walleye research includes connecting spawning habitat quality and quantity with hatching and recruitment success and continued evaluation of influential factors in the first year and later life stages. Management should focus on identifying and protecting high quality lakes and important habitats (e.g., spawning), along with understanding habitat and biological factors to determine whether walleye populations can be improved (e.g., habitat projects, stocking, regulations) or in some cases not managed for altogether (e.g., too warm).
Article
Age‐0 Walleye Sander vitreus are stocked throughout North America to maintain and supplement populations. Predation has been implicated as a factor limiting survival of stocked age‐0 Walleye; however, timing, duration, and extent of post‐stocking predation remains uncertain. Our objectives were to estimate the abundance of predators in areas adjacent to stocking locations, estimate temporal variation in the proportion of stocked age‐0 Walleye (98‐287 mm) in predator diets, and estimate the total proportion of stocked age‐0 Walleye that were consumed. Largemouth Bass Micropterus salmoides, Northern Pike Esox lucius, and adult Walleye diets were collected from East Okoboji and West Okoboji, Iowa, USA before and after age‐0 Walleye stocking and bioenergetics models were used to estimate the number of age‐0 Walleye consumed from stocking through ice‐up. During both years, Largemouth Bass had the highest densities in West Okoboji, whereas densities of all other predators was similar in East Okoboji. The highest proportions of age‐0 Walleye in predator diets (up to 1.0) generally occurred within 14 days after the most recent stocking event, with the proportion of age‐0 Walleye in predator diets decreasing thereafter. Northern Pike (0.12 ± 0.32 age‐0 Walleye per individual) had the highest mean proportion (± SD) of age‐0 Walleye in their diets followed by Largemouth Bass (0.11 ± 0.30 age‐0 Walleye per individual) and adult Walleye (0.04 ± 0.20 age‐0 Walleye per individual). At the end of 2016, the estimated proportion (± 95% confidence interval) of age‐0 Walleye consumed in East Okoboji was 0.15 (± 0.08) and 0.29 (± 0.13) in West Okoboji. At the end of 2017, the estimated proportion of age‐0 Walleye consumed was 0.47 (± 0.16) in East Okoboji and 0.64 (± 0.02) in West Okoboji. Overall, predators consumed large proportions of stocked Walleye, suggesting that alternative stocking practices should be considered.
Article
Strain performance evaluations are vital for developing successful fishery management and restoration strategies. Here, we utilized genotypes from 36 microsatellites to investigate hatchery strain contribution to collections of naturally produced lake trout sampled across Lake Michigan. Strain composition varied by area, with recoveries of Seneca Lake strain exceeding expectations based on stocking records in northern Lake Michigan but performing similarly to other strains in southern Lake Michigan. Interstrain hybrids were present at moderate frequencies similar to expectations based on simulations suggesting that strains are interbreeding randomly. We hypothesize that the superior performance of the Seneca Lake strain in northern Lake Michigan is partially due to adaptive advantages that facilitate increased survival in areas with high mortality from sea lamprey predation such as northern Lake Michigan. However, when this selective pressures is lessened, the Seneca Lake strain performs similarly to other strains. Our study demonstrates that strain performance can vary across small spatial scales and illustrates the importance of conducting thorough strain evaluations to inform management and conservation.
Article
The USA and Japan differ in their approaches to managing inland recreational fisheries. The USA uses a public property rights regime whereby access rights are assigned to the states, which manage the fishery resource for the public good. Japan uses a common property rights regime whereby access rights for waterways are assigned to fishery unions, which manage the resource for the benefit of their members. Members of fishery unions are likely to develop an emotional attachment to the fishery that results in few regulation violations or illegal fish introductions. The USA would benefit from actions that promote such a caretaker attitude toward the environment. Habitat improvement is a major activity in the USA but is less prevalent in Japan where stocking is the dominant management activity. Catch-and-release angling, size restrictions, and employment of professional fisheries biologists are more prevalent in the USA compared to Japan. The USA has a tax on fishing equipment that funds management activities whereas such a funding source is lacking in Japan. Despite differences in management regimes, both countries face similar challenges in recruiting new anglers and meeting the conflicting mandates to enhance sport fisheries while conserving native species.
Article
Stocking and electrofishing occurrence and abundance data for northern pike Esox lucius L. in >3800 km of French rivers across 7 years were compared to assess the effect of recreational fisheries stocking programmes on wild pike populations. A positive relationship was found between the additive effect of stocking and the size of the stocked pike. However, the stocking programmes implemented in France by recreational fishery managers from 2008 to 2013 increased the probability of pike occurring in the river network, without increasing abundance in well‐established pike populations, because pike stocked in their early‐life stages were used in most of the stocking programmes.
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The European lobster ( Homarus gammarus ) forms the base of an important fishery along the coasts of Europe. However, stocks have been in decline for many years, prompting new regulations in the fishery and also restocking efforts. An important feature of any restocking effort is the assessment of success in the number of released juveniles that stay and become adult over time. Here, we tested the power of a SNP DNA marker panel developed for population assignment to correctly infer parentage on the maternal side of lobster larvae, in the absence of known fathers, using lobsters included in a current restocking effort on the Swedish west coast. We also examined the power to reconstruct the unknown paternal genotypes, and examined the number of fathers for each larval clutch. We found that the 96-SNP panel, despite only containing 78 informative markers, allowed us to assign all larvae to the correct mother. Furthermore, with 10 genotyped larvae or more, confident paternal genotypes could be reconstructed. We also found that 15 out of 17 clutches were full siblings, whereas two clutches had two fathers. To our knowledge, this is the first time a SNP panel of this size has been used to assess parentage in a crustacean restocking effort. Our conclusion is that the panel works well, and that it could be an important tool for the assessment of restocking success of H. gammarus in the future.
Article
In addition to accidental aquaculture escapees, an increasing number of freshwater fish expressing different domestication levels are voluntarily released into the wild primarily as stocking supplement for fisheries and for conservation programmes. Because domestication modifies individual traits and because subtle changes in intraspecific variability can impact ecological dynamics, we argue that these purposeful introductions of domesticated fish may impact the functioning of recipient ecosystems. We posit that purposely introduced domesticated fish could be considered as native invaders and be investigated and managed using frameworks developed for biological invasions. Studies identifying the relative importance of the different ecological mechanisms leading to these ecosystems impacts and quantifying how the intensity of introduction and the level of domestication modulate their ecosystem impacts are needed. This will lead to a better appreciation of how the benefits from releasing domesticated fish are offset by the ecological costs on freshwater ecosystem functioning caused by human‐induced local modification of intraspecific diversity patterns.
Article
While the potential effects of pathogens spread from farmed fish to wild populations have frequently been studied, evidence for the transmission of parasites from wild to farmed fish is scarce. In the present study, we evaluated natural bacterial and parasitic infections in brown trout ( Salmo trutta m. fario ) collected from the Černá Opava river (Czech Republic) as a potential source of infections for rainbow trout ( Oncorhynchus mykiss ) reared in a flow-through farm system fed by the same river. The prevalence of bacterial and protozoan infections in farmed fish was comparable, or higher, than for riverine fish. Despite this, none of the infected farmed fish showed any signs of severe diseases. Substantial differences in metazoan parasite infections were observed between wild and farmed fish regarding monogeneans, adult trematodes, nematodes, the myxozoan Tetracapsuloides bryosalmonae found in riverine fish only, and larval eye-fluke trematodes sporadically found in farmed fish. The different distribution of metazoan parasites between brown and rainbow trout most probably reflects the availability of infected intermediate hosts in the two habitats. Despite the river being the main water source for the farm, there was no significant threat of parasite infection to the farmed fish from naturally infected riverine fish.
Article
Many inland fisheries are supported by stocking of hatchery‐produced fish, and fisheries managers often face difficult decisions regarding strain selection. Stocking evaluations designed to quantify differences in strain performance provide valuable data for designing stocking programs. Here, we use genetic tools to investigate capture rate of two strains of Muskellunge stocked in Wisconsin lakes. We genotyped a total of 1,011 Muskellunge at 13 microsatellites and used data from five reference populations to assign fish stocked in four Wisconsin lakes to their strain of origin. The strains stocked in these lakes were derived from Wisconsin populations in the Upper Chippewa and Wisconsin River drainages and from Leech Lake, Minnesota. Leech Lake Muskellunge demonstrated much lower capture rates than the Wisconsin strain, but results were variable, with a 10% capture rate of Leech Lake strain fish in Lake Monona and 2% capture rate in Lake Wissota despite similar stocking rates (~25%) in both lakes. We hypothesize that the higher capture rates of Wisconsin strain Muskellunge could be due adaptative advantages of the Wisconsin strain in these waters and suggest that managers continue to stock the nearest native (i.e. Wisconsin) strain to achieve the highest return on investment.
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1.Captive propagation can lead to phenotypic change in fish populations, but the broader community‐level consequences of captive phenotypes remain largely unknown. 2.We investigate the degree to which captive propagation alters the phenotypes and ecological roles of fish stocked into wild communities. We focus on captive propagation of western mosquitofish (Gambusia affinis) for biocontrol, which represents one of the largest‐scale production efforts for any fish released into the wild. 3.Captive propagation in mosquitofish consistently generated novel mixtures of morphological and behavioural traits that deviate from those of wild populations. 4.A mesocosm experiment showed that mosquitofish from captive propagation facilities differ from wild fish in their effects on aquatic community structure by shifting their consumption to less‐mobile, benthic prey. 5.Synthesis and applications. Captive‐propagated and translocated wild fish stocks not only differ in phenotype, but can have substantially different ecological effects on the communities into which they are introduced. Therefore, captive propagation programs involving continual release should expand their concerns beyond altered phenotypes and fitness to include whether propagated fish actually provide the intended ecological roles and services associated with their wild counterparts. Infusions of wild alleles and captive environments that mimic wild conditions are recommended strategies to retain the desired ecological role of captive‐propagated fish. This article is protected by copyright. All rights reserved.
Article
Distinguishing hatchery‐reared fishes from wild conspecifics can be required to quantify the success of augmentation programmes. This study estimated the probability of identifying calcein‐marked, hatchery‐reared Colorado pikeminnow Ptychocheilus lucius Girard from external and internal structures. Both control and marked fish held in the laboratory were correctly identified 80% of the time after 300 days. A fluorometer was more accurate 180 days post‐marking, whereas visual observation was more discriminating at 300 days. There were no differences in detection rates among structures in laboratory fish, and for most structures of fish held outdoors, detection rates were <20%. Overall, a strong negative effect of light on mark persistence was observed. Also, an initial positive effect of fish size on mark fluorescence and a negative effect of fish growth were detected. These results suggest the potential use of calcein as a batch‐marking tool would be aided by future studies that better quantify light exposure and calcein mark persistence in both field and experimental settings.
Article
Hydropower production is one of the greatest threats to fluvial ecosystems and freshwater biodiversity. Now that we have entered the Anthropocene, there is an opportunity to reflect on what might constitute a ‘sustainable’ Anthropocene in the context of hydropower and riverine fish populations. Considering elements of existing practices that promote favorable social-ecological outcomes (i.e., ‘bright spots’) is timely given that there are plans to expand hydropower capacity in previously undammed rivers, intensify dam development in some of the world’s largest river systems, and re-license existing facilities. We approach this from a pragmatic perspective: for the foreseeable future, hydropower will likely remain an important source of renewable electricity. To offer support for moving toward a more ‘sustainable’ Anthropocene, we provide syntheses of best practices during the siting, design, construction, operation, and compensation phases of hydropower development to minimize impacts on inland fish. For each phase, we offer positive examples (or what might be considered ‘bright spots’) pertaining to some of the approaches described within our syntheses, acknowledging that these projects may not be viewed as without ecological and (or) societal detriment by all stakeholders. Our findings underscore the importance of protecting critical habitat and free-flowing river reaches through careful site selection and basin-scale planning, infrastructure designs that minimize reservoir effects and facilitate safe passage of fish, construction of hydropower plants using best practices that minimize long-term damage, operating guidelines that mimic natural flow conditions, and compensation that is lasting, effective, inclusive, and locally relevant. Learning from these ‘bright spots’ may require engagement of diverse stakeholders, professionals, and governments at scales that extend well beyond a given site, river, or even basin. Indeed environmental planning that integrates hydropower development into broader discussions is important for conserving regional biodiversity and ecosystem services.
Article
Hybridization can profoundly affect the genomic composition and phenotypes of closely related species, and provides an opportunity to identify mechanisms that maintain reproductive isolation between species. Recent evidence suggests that hybridization outcomes within a species pair can vary across locations. However, we still don't know how variable outcomes of hybridization are across geographic replicates, and what mechanisms drive that variation. In this study, we described hybridization outcomes across 27 locations in the North Fork Shoshone River basin (Wyoming, USA) where native Yellowstone cutthroat trout and introduced rainbow trout co‐occur. We used genomic data and hierarchical Bayesian models to precisely identify ancestry of hybrid individuals. Hybridization outcomes varied across locations. In some locations, only rainbow trout and advanced backcrossed hybrids towards rainbow trout were present, while trout in other locations had a broader range of ancestry, including both parental species and first‐generation hybrids. Later‐generation intermediate hybrids were rare relative to backcrossed hybrids and rainbow trout individuals. Using an individual‐based simulation, we found that outcomes of hybridization in the North Fork Shoshone River basin deviate substantially from what we would expect under null expectations of random mating and no selection against hybrids. Since this deviation implies that some mechanisms of reproductive isolation function to maintain parental taxa and a diversity of hybrid types, we then modeled hybridization outcomes as a function of environmental variables and stocking history that are likely to affect prezygotic barriers to hybridization. Variables associated with history of fish stocking were the strongest predictors of hybridization outcomes, followed by environmental variables that might affect overlap in spawning time and location. This article is protected by copyright. All rights reserved.
Article
Stocking is a management tool that provides fish directly to anglers and can partly address concerns over low catch rates. Although stocking is recognized as an effective management tool for addressing low catch rates, stocking fish represents a considerable investment. Stocking may not be a viable option if fish do not persist within targeted areas, are not accessible to anglers, or pose a potential risk to sensitive species. The goal of this study was to assess the survivorship, movement, and persistence of stocked Rainbow Trout Oncorhynchus mykiss (RBT) within the walk‐in section of Lees Ferry, Colorado River, Arizona in order to evaluate the efficacy of targeted stocking for this fishery. To meet this goal, we used acoustic telemetry to monitor stocked trout and assess movement out of the management area. A multi‐state model was used to distill spatiotemporal telemetry data into a multinomial state response, the spatial zones of our study area, to evaluate the efficacy of targeted stocking. The 3‐month survival estimate of RBT that remained within the walk‐in section without transitioning was 37.3 – 68.1% based on the 95% confidence interval (CI). Persistence, which accounts for movement, of RBT within the walk‐in section after 3‐months was estimated to be 29.6 – 33.5% of the original stocked population. Three‐month transition rates downstream out of the walk‐in section (12.8 – 15.8% CI) were higher than upstream transition rates out of the walk‐in section (7.7 – 10.0% CI). These findings suggest that targeted stocking can effectively supplement the fishery at the walk‐in section of Lees Ferry based on the relatively high persistence of stocked RBT within the targeted area. However, managers will need to weigh stocking densities, transition probabilities, and catch rate goals to determine an acceptable level of risk to the native populations while addressing management goals.
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In 1996, fishery administrators from every U.S. state were surveyed about an array of coldwater management topics ranging from the composition of coldwater fishery resources, to threats facing resources, to expertise and strategies employed by the agency. Administrators in 49 states returned completed surveys and provided information on the general challenges facing coldwater fishery resources and the conditions under which these resources are managed. For example, 47 states managed coldwater fisheries. Of these, 38 cited habitat-related problems as the most commonly identified obstacles to maintaining self-sustaining trout or salmon populations. Yet in spite of this observation, funding for aquatic habitat programs through fishery management agencies was generally but a fraction of their budgets. In contrast, the states cumulatively operated 369 coldwater hatcheries, which consumed sizable portions of their annual budgets, and licensed an additional 1,200 private coldwater facilities nationwide. Twelve states had assessed the environmental impacts and 11 states the economic impacts of their facilities. In terms of resource planning, 25 states managed coldwater resources under the umbrella of a strategic plan, and 10 managed on an ecosystem-or watershed-based approach. Ultimately, these and other facts suggest a misalignment between the problems facing many coldwater fisheries and management programs in use by some state agencies to counter these problems. This disconnect is likely due to a mix of our profession's institutional history, the way agencies are funded, and public expectation; therefore, overcoming this disconnect will require an objective presentation of facts and open dialogue among professionals and stakeholders regarding management goals and the tools used to reach these goals.
Article
The use of cultured fishes by fisheries agencies is a long-standing management technique. In recent decades, however, potential negative impacts of fish stocking programs have received increased attention, particularly as they affect native fish communities and the genetic integrity of wild fish populations. In 1994, a facilitated workshop was organized to develop recommended procedures for the use of cultured fishes that would be compatible with these broader environmental concerns. We administered a survey to state and provincial fisheries management agencies in the United States and Canada to determine the current status of fish culture and stocking programs and assess progress toward adoption of these procedures. With 54 of 62 agencies reporting, our results indicated that stocking programs continue to be an integral part of management programs, but that substantial progress has been made toward addressing concerns about potential negative effects of cultured fishes. The percentage of responding agencies reporting use of management plans in which stocking was considered as part of a larger management program more than doubled in the years since 1980. Consistent with this finding, agency emphasis on alternative management approaches was evidenced by a twofold greater increase in expenditures on habitat management programs relative to culture programs in six agencies that provided budget figures. The percentage of responding agencies evaluating appropriateness of stocking through the use of formal criteria on at least half the waters where cultured fish were used tripled since 1980, and decisions not to stock due to potential impacts on biodiversity or the genetic integrity of recipient fish communities were reported to be four times more likely today than in 1980. Emphasis on the use of native fishes in stocking programs since 1980 was reported to have increased for more than half the agencies responding to our survey, and the number of agencies reporting development of broodstock plans for at least some of the species they cultured also doubled since 1980. Agency perceptions of angler attitudes concerning the importance of stocking indicated that the percentage of anglers who believed that stocking was the primary or only solution to low fish abundance remained high, at 61%, a decline of only 27% from reported attitudes in 1980. While positive strides have been made by agencies toward more careful evaluation of the appropriateness of stocking for achieving management objectives and in the institution of programs to minimize impacts of cultured fishes, these policies have not been adopted by all agencies, nor are they routinely used on all stocked waters by the agencies that have them. To make continued progress, agencies may be required to make difficult decisions regarding allocation of funding, and a more concerted effort to educate anglers and reduce public pressure for stockings will be needed to create an atmosphere where reduced emphasis on stocking is possible. The American Fisheries Society should play a continuing role in providing opportunities for scientists and policy makers to interact and discuss prevailing and emerging issues relative to the use of propagated fishes in resource management.
Article
This is an account of nineteenth-century efforts to naturalize alien freshwater and anadromous fish in California. Between 1871 and 1896, government and private groups imported and released twenty-one species. Of these, fourteen became established, and at least seven are still important sport or food fish (see Table 1). No other state made a comparable effort during this period. The counterflow of native fishes to other regions was much smaller; only two Pacific slope species, the Chinook salmon (Oncorhynchus tshawytscha) and the rainbow trout (Salmo gairdneri), were transported out of their native range before 1900. This one-sided exchange of fishes and the attendant transformation of fisheries was one aspect of a worldwide process that peaked in the nineteenth century, one that Alfred Crosby described as 'biological imperialism,' in which European biota, both domestic and wild, colonized the temperate world. As illustrated in this study, a variant of this movement took place during the internal colonization of North America. Only two European species came to California, the carp (cyprinios carpio) and the brown trout (Salmo trutta). The rest of the migrants were native to the eastern United States. Like Europeans, Americans were eager to naturalize familiar species in their new homelands, but less enthusiastic about the movement of 'new' plants and animals back to their old homes.
Article
Further tagging experiments in Michigan with spring and fall plantings of brook trout (Salvelinus f. fontinalis, brown trout (Salmo trutta), and rainbow trout (Salmo gairdnerii irideus) from which recoveries were made during the 1942 trout season confirmed the conclusion that spring release of adult or near adult hatchery-reared brook trout and rainbow trout is more desirable than the fall planting of fish of a similar size. In some instances fall stocking of brown trout may furnish as good fishing in the following seasons as does spring planting.Recoveries of planted fish past the first season of availability ranged from 0.0 to 2.5 per cent in the second season and from 0.0 to 0.5 per cent in the third season.In either spring or fall planting of legal-sized fish, no advantage was gained by scattering the fish widely over the stream areas stocked.Eighty five per cent or more of the planted trout recovered were caught within 10 miles of the point of release, regardless of the season or method of planting. Brown trout moved the least and rainbow trout the most. About one-fourth of the brook trout tended to move 3 to 10 miles downstream, and the majority of the remainder were caught within 3 miles of the locality of release. More rainbow trout than any other species were recaptured 10 or more miles from the point of release.Fall plantings of adult brook trout in lakes were recovered at the rate of 56.7 per cent (range, 13.0 to 88.1 per cent). Unfortunately, a small percentage of the anglers removed an average of 89.4 per cent of the total catch during the opening weeks of the trout season. The average recovery from two spring plantings of brook trout in East Fish Lake in Michigan was 68.5 per cent.A brief review of the literature substantiates the conclusions reached as a result of the Michigan experiments. Differences in experimental procedure are pointed out, and some reasons are offered for the failure of fish planted in streams in the fall to survive the winter season.
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Greenback cutthroat trout recovery plan better roles for fish stocking in aquatic resource management. Pages 527- 547 in Uses and effects of cultured fishes in aquatic ecosystems
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