Trout Fishery Research Articles

Imagination, Reality, and Reproduction: Comparing Perceptions of Coastal Sea Trout Anglers, Real Catches, and Sea Trout Spawning Activity

ABSTRACTSustainable management of recreational fisheries requires balancing angler attitudes and behaviour with fisheries' biological potential. Herein, we investigated the balance in the sea‐run brown trout (Salmo trutta) fishery around the Swedish island of Gotland using data collected through a creel survey, test fishing, and spawning returns to selected streams. Anglers accurately anticipated catches of large fish but underestimated the role of natural reproduction in supporting the stock. Female sea trout entering spawning streams and post‐spawn sea trout caught on the coast were significantly larger than spawning males and non‐spawned fish, and were particularly important for the fishery. Larger sea trout also faced a higher level of harvest pressure than other sizes. Small changes to angler preferences, harvest rates, or regulations could significantly influence characteristics and sustainability of this fishery. The scale and direction of these changes merit further investigation.

COVID-19 Pandemic Effects on Angler Effort and a Brown Trout Population in a Driftless Area Stream in Southeast Minnesota

Abstract Early opinions of the COVID-19 pandemic included equivocal notions of whether the pandemic would result in more or less angler effort and harvest in recreational fisheries. Early papers also suggested using changes in angling license sales to infer changes in angler effort but expressed concern about adequate assessment of pandemic effects on fisheries because of interruptions to routine assessment programs. To assess pandemic effects on angler effort at a stream trout fishery, a trail camera was installed, immediately prior to implementation of a statewide stay-at-home order, at a representative stream trout angling site that is part of a long-term fish monitoring program. The trail camera was deployed through the trout harvest angling season from the peak pandemic year of 2020 through cessation of most restrictions in 2022. Statewide sales of angling licenses and trout stamps were assessed through this time to compare with angler effort measured with the trail camera. Annual trout population assessments were examined for pandemic effects in conjunction with angler effort. Anglers were present on 84% of days in 2020, 66% in 2021 and 69% in 2022. Following the pandemic peak of 603 angler-hours in 2020, angler-hours declined by -23% between 2020 and 2021, and by -16% between 2020 and 2022; whereas statewide sales of licenses and trout stamps only declined by -4% between 2020 and 2021 and -11% between 2020 and 2022, suggesting more angler pressure at the study site than could be inferred by changes in license or trout stamp sales. Higher pressure during the pandemic was due in part to more anglers younger than 20 years old. Despite higher angler pressure in 2020, there was no long-term effect on the Brown Trout population, as adult abundance in 2021 and 2022 exceeded abundance in every year from 2017 to 2020. These data add to a limited number of similar field-based pandemic studies coupling changes in angler use with fish population responses and should provide further insight into the broader assessment of COVID-19 pandemic effects.

Declining geomorphic diversity and potential adaptive management opportunities on a highly regulated reach of the Bighorn River, Montana

ABSTRACT Rivers downstream from dams often experience decreased flow variability and disrupted sediment transport. We investigated a highly regulated 35.5-kilometre reach of the Bighorn River, downstream from Yellowtail Dam, emplaced in 1965. This dam created a thriving trout fishery, but more recently, side channel networks and habitat diminished. We document how the Bighorn River's anabranching morphology responded to flow regulation and a near cessation of sediment supply. Geomorphic diversity drastically decreased since 1939 and the Bighorn River abandoned numerous side channels. By 1980, geomorphic loss slowed, and the river became laterally static. The 1980 river and side channel network could represent the maximum areal extent of a downscaled morphology, maintained through restoration and adaptive management. However, side channel restoration alone will not return natural alluvial processes to this river reach. The Bighorn River needs sediment to reinstate dynamic lateral movement, even within a downscaled morphology. Sediment augmentation is an option, but more complex to implement on rivers where potential downstream impacts and landowners must be considered. The decline of geomorphic diversity and potential adaptive management solutions on the Bighorn River has wide applicability to numerous dammed rivers, where similar changes to the flow and sediment transport regime are common.

Benthic macroinvertebrate community structure in nutrient‐rich, spring‐fed streams recently invaded by non‐native New Zealand mud snails

Abstract Ecological roles of non‐native species can vary over space and time due to abiotic factors and characteristics of the invaded communities. For instance, nutrient availability, temperature, and flow regime can influence invasion outcomes in freshwaters. This variability makes it challenging to predict non‐native species' effects in newly introduced areas. New Zealand mud snails (Potamopyrgus antipodarum; NZMS) are among the most widespread aquatic invasive species globally and have recently been detected in highly productive, spring‐fed streams in the upper mid‐west U.S.A. that are important trout fisheries. We hypothesised that the nutrient‐rich, thermally stable groundwater‐fed streams would provide favourable conditions for NZMS populations, potentially amplifying their effects on native communities. We surveyed benthic macroinvertebrate community structure at 10 streams representing a gradient of NZMS densities in the Driftless Area of southern Wisconsin. At five of the streams, we quantified temporal variation in NZMS and other benthic macroinvertebrates over three seasons. NZMS populations varied considerably across sites and over time, ranging from a few hundred to over 70,000 snails/m2. NZMS numerically represented as much as 97% of the invertebrate community at the highest density sites. At two sites, NZMS increased in population density by 50‐fold and 22‐fold over the survey duration, while at other sites their densities were relatively constant. Based on a principal components analysis summarising stream environmental variables, NZMS densities were negatively associated with stream discharge and positively associated with nitrogen and phosphorus concentrations. The total density and biomass of all benthic invertebrates, and Ephemeroptera and Amphipoda in particular, were negatively associated with NZMS density and biomass. Based on multivariate analyses, overall benthic community composition differed based on NZMS invasion status, as well as across seasons. These results suggest that the environments of southern Wisconsin spring‐fed streams provide favourable conditions for NZMS populations, allowing them to dominate some benthic communities. NZMS effects are likely to vary strongly across streams and over time within streams, highlighting the importance of future work to mechanistically test biotic and abiotic factors influencing their abundance.

Angling party persistence and visitation in a recreational Lake Trout fishery: Relative influence of travel distance and fuel costs

AbstractObjectiveCormack–Joly–Seber (CJS) mark–recapture analysis was used to estimate the effect of travel distance and fuel costs on angling party persistence (i.e., survival = probability of remaining in the Lake Trout Salvelinus namaycush fishery from year‐to‐year) and visitation (i.e., detection = probability of detection at the access point) over a 14‐year period (2006–2019) for the Lake Trout recreational fishery in Lake Opeongo, Ontario, Canada.MethodsBoat identification numbers, positioned near the bow and present by law, were used as “tags” in the CJS analysis. Complete trip creel interviews at the sole access point provided information on trip characteristics.ResultThe long‐term mark–recapture analysis of individual angling parties showed travel distance had a significant negative effect on party persistence among years and visitation within years. The distance effect was strongest for visitation, with visitation having a more negative relationship with distance than persistence. Persistence in the Lake Trout fishery was insensitive to fuel costs while the fuel cost covariate had a small though significant and negative effect on visitation. Time‐varying CJS models were ranked low with little model weight indicating the distance effect estimated for Lake Opeongo was a general phenomenon and not year dependent.ConclusionCormack–Joly–Seber mark–recapture analysis cleanly separated effects of travel distance and fuel cost between visitation versus persistence for Lake Trout angling parties. Prior to this analysis, travel costs were typically associated with visiting a recreational fishery, while here we have shown that travel costs can be associated with persisting as anglers in a fishery independent of visitation patterns. Long‐term monitoring of angling parties provides unique insights into angling patterns that can aid in travel cost estimation.

Using state‐space models to estimate recreational angling effort and infer processes that regulate angler dynamics

AbstractObjectiveState‐space models are a flexible modeling approach and are often fit to ecological time series data exhibiting temporal autocorrelation. Traditionally, angler effort data collected using on‐site creel surveys are analyzed using design‐based methods. With some exceptions, state‐space models are rarely used to model creel survey data that are also generally a time series of temporally autocorrelated counts.MethodsIn this study, we demonstrated how to fit state‐space models to a time series of angler counts in 11 sections of three trout fisheries in Idaho. The basic model was extended to make inference about processes that may regulate angling dynamics, such as “population growth rate” of angling effort and recreational carrying capacity.ResultEstimated angling effort varied from 21,179 h in the lowermost section of the Henrys Fork Snake River to 199,457 h in the uppermost section of the South Fork Snake River. The finite population growth rate of angling effort was 1.82 when transitioning from a weekday to a weekend, suggesting that angling effort was 1.82 times greater, on average, on Saturdays than on Fridays, and the population growth rate was 0.38 (i.e., 0.38 times smaller) when transitioning from a Sunday to a Monday. Estimated carrying capacity among fishery sections varied from 129 daily hours of angling effort on the Big Lost River to 693 h on the middle section of the South Fork Snake River. Carrying capacity was 1.88 times higher on fishery sections that had ≥0.5 access points/km than on sections with <0.5 access points/km.ConclusionThe state‐space models used in this study can be modified or extended to fit a variety of data types or can be used to evaluate additional hypotheses regarding the angling process.

Spatiotemporal and multispecies comparisons between a citizen science platform and recall surveys in recreational fisheries

Smartphone applications for anglers that function as citizen science platforms are an alternative to the traditional survey methods that are used to collect data from recreational fisheries. Comparisons between these two methods are needed to understand the impacts of the biases associated with data generated from smartphone applications. However, such comparisons are uncommon, especially for multiple fisheries over time and across space. In this study, we compared catch and effort data from an electronic citizen science platform for anglers with an offsite web-based recall survey for consecutive (i) 3-month periods in a spatially distinct (i.e., the Danish island of Funen) sea trout (Salmo trutta) fishery (2017–2020), (ii) 6-month periods in coastal sea trout and coastal/offshore cod (Gadus morhua) fisheries across eight ICES management areas (2016–2020), and (iii) 6-month periods in a freshwater pike (Esox lucius) fishery (2016–2020). Catch and effort data from the two surveys were, in most cases, consistently similar over time for the Funen sea trout and Danish freshwater pike fisheries. In contrast, we found that the recall survey estimates were consistently 100–200% larger than the citizen science platform for both sea trout and cod in ICES areas. Our findings suggest that the applicability of electronic citizen science platforms for anglers can be fishery-specific, and that systematic bias may occur.

Popular solunar tables fail to predict fishing success in North American recreational freshwater trout fisheries

The solunar theory proposes that the position of the sun and moon can be used to predict activity rates in fish and game species. Several free and premium services use this theory to provide tables predicting optimal dates and times for fishing and hunting success. The efficacy of these services was tested by comparing catch per unit effort (CPUE) in a recreational freshwater trout fishery with daily solunar values and coincidence of fishing trips with peak solunar times. CPUE was also compared to environmental variables including lunar phase, lunar illumination, and wind speed. Values predicted by each of the solunar services were strongly correlated to each other and to lunar phase, however, no significant relationship was found between CPUE and any of the solunar values tested, lunar phase, or lunar illumination. Ambient air temperature showed a positive relationship with CPUE, and was a more effective predictor of fishing success than any of the solunar tables tested.

The lesser of two evils: the role of an instream barrier to control the distribution and invasive potential of non-native fish species in the Mooi River, South Africa

Context Recreational angling has a history of species introductions causing significant loss of native biodiversity. Despite this, it represents a large economy supporting many livelihoods. The Mooi River, South Africa, supports trout fisheries in its upper reach. A weir was constructed to mitigate the loss of a natural barrier, now inundated by a large impoundment. Aims We evaluated the Inchbrakie Weir’s efficacy in restricting movement of non-native fish. Methods We evaluated the weir as a fish barrier by using fish surveys. We used species distribution modelling to assess the potential for bass to invade the upper reaches should they make their way past the barrier. Key results Our surveys detected three bass species in the study area, including Micropterus salmoides upstream of the fish barrier. Micropterus dolomieu was the main concern with the highest invasion potential, but was not found upstream of the fish barrier. Distribution modelling showed that suitable habitat was available for all three detected bass species, with M. salmoides showing the greatest potential in the upper Mooi River. Implications Invasion by Micropterus spp. concerns the local trout fishery and native fauna persistence. We suggest a long-term continuous monitoring plan to detect the early invasion of M. dolomieu and that a pre-emptive management plan is in place.

Reflections on a Career Unplanned

Sometimes life takes unexpected turns. I never planned to be a marine biologist; yet, after a long and unpredictable journey, that’s exactly where I found myself. After obtaining my B.S. in Fishery Biology from Colorado State University, I found myself meandering from job to job like a golden retriever following some vague scent. At first, I was hired by the Wyoming Game and Fish Department to work seasonally in Grand Teton National Park on the freshwater trout fisheries. Soon thereafter, I found myself cultivating oysters, clams, and other shellfish in California. The skills I developed there as an algologist led to my subsequent employment developing a Spirulina culture facility near Santa Cruz, CA. My next position, which ultimately shaped my career, was helping to establish the Caicos Conch Farm in the Turks and Caicos. I was subsequently hired to help develop a conch research program for the State of Florida. Thus began 35 years focusing on hatchery—based stock replenishment, ecological dynamics, reproductive ecology, ecotoxicology, metapopulation dynamics, gene expression, and other issues impacting conch distribution and recovery from local overexploitation. Simultaneously, the diverse aquatic and terrestrial ecosystems in Florida were rapidly changing due to a changing climate superimposed on an expanding human footprint. This provided opportunities work on crafting adaptation solutions for both ecosystems and societies. In 1996, I was offered a leadership position in the Gulf and Caribbean Fisheries Institute, a role within which I remain active. Taken as a whole, these positions have been rich in both scientific explorations and policy development. Despite my best efforts at retiring, the opportunities to explore new research approaches and to develop new programs conspire to keep me pursuing new and exciting projects.

Analysis of a Catch‐and‐Harvest Fishing Contest for Brown Trout Spanning 50+ Years: Long‐Term Trends Influenced by Fisheries Management Actions and Angler Behavior

AbstractLong‐term effects of evolving fisheries management, changing angler practices, and stream habitat development on stream trout fisheries in southeastern Minnesota, USA, were examined by analyzing data on >1,000 weekly winners from a single‐watershed, catch‐and‐harvest Brown Trout Salmo trutta fishing contest spanning 54 years. The weights of winning fish declined significantly across the period examined. No‐entry weeks increased within the past two decades, corresponding to expanding catch‐and‐release fishing. The streams that produced winning fish shifted as stream access increased, degraded stream habitat was improved, and various angling restrictions were instituted. Most winning fish were caught with live or preserved bait, although the proportion of winners caught with artificial lures doubled from the 1960s to the 2010s. The interpretation of contest results must consider various angling regulations (e.g., protected slot lengths, artificial lures only, catch and release only) that were placed on some reaches during and after the 1980s, increasing voluntary catch‐and‐release practices of contemporary anglers, and expanding stream access and habitat improvements within the watershed.

A travel cost recreation demand model examining the economic benefits of acid mine drainage remediation to trout anglers.

Acid mine drainage (AMD) is a global environmental problem which has well-documented effects on the physical, chemical, biological, and ecological characteristics of waterways. Less well examined are the economic benefits generated by costly AMD remediation efforts. This research examines trout angler willingness-to-pay (WTP) to maintain fisheries quality benefits resulting from AMD remediation on the North Branch of the Potomac River (NBPR), Maryland. The NBPR has a history of severe AMD-related degradation previously rendering the waterbody unsuitable for many outdoor recreational activities such as trout fishing. However, extensive NBPR AMD remediation activities including nine automated limestone dosers that neutralize acidic water and improve water quality have been critical to developing and maintaining a high quality recreational trout fishery with hatchery-raised stocked trout and naturally reproducing populations of wild trout. To examine trout angler WTP to maintain current NBPR trout fishing quality and hence avoid plausible fishing quality reductions associated with the elimination of nine NBPR limestone dosers, a travel cost recreation demand model of trout angler fishing site choice was developed using data from a survey of Maryland non-tidal anglers. Model results reveal that annual Maryland trout angler WTP to maintain current NBPR trout stocking levels and wild trout abundance, relative to the elimination of the NBPR as a trout fishing site, is about $850,000. These economic benefits to a single stakeholder group - Maryland trout anglers - exceeds the total estimated $340,000 in annual operations and maintenance costs associated with all Maryland limestone dosers. While the positive net economic benefits produced by limestone dosers provide a justification for continuing annual limestone doser expenditures, it's important to note that total economic benefits are likely much higher, as many non-trout fishing benefits remain unaccounted for in this analysis. The approach in this manuscript can serve as a model for practitioners regarding the use of fisheries data and recreational fisher site choice to estimate fishing-related economic benefits from past or for future AMD remediation activities. Given anticipated substantial investments in AMD remediation, additional research in this area is much needed to evaluate past and guide future remediation activities.

Field-Based Selenium Partitioning Coefficients and Trophic Transfer Factors for Cutthroat Trout Fisheries from Four Montane Lakes, Colorado, USA

La mayoría de los estudios sobre la bioacumulación de selenio (Se) y la transferencia trófica en hábitats de agua dulce se han enfocado principalmente en lugares lóticos y lénticos en regiones seleníferas elevadas. En contraste con los reportes anteriores, nos propusimos investigar la fragmentación del Se en el agua a los niveles tróficos posteriores en lagos montañosos oligotróficos, utilizando concentraciones en agua, sedimento, perifiton, algas filamentosas, contenido estomacal y tejidos de trucha degollada (Oncorhynchus clarkii), analizados mediante Espectrometría de Masas con Plasma Acoplado Inductivamente (ICP-MS por sus siglas en inglés). Los valores indicadores del nivel uno (partículas en agua) de los coeficientes de partición (Kd) o factores de enriquecimiento (EF) fueron mayores a 1,641,000 (L/kg de peso seco) y menores a 14,843. Los valores de los coeficientes de partición del lago Upper Sand Creek en el Great Sand Dunes National Park and Preserve, fueron 36,529 en sedimentos, 28,000 en algas filamentosas y 1,641,000 en perifiton. En el lago Lower Sand Creek, los coeficientes de partición fueron de 14,843 en sedimentos, 17,250 en algas filamentosas y 32,415 en perifiton. Los valores en el nivel dos (partículas en invertebrados del contenido estomacal de las truchas) para la función de transferencia trófica promedio de los invertebrados del lago Upper Sand Creek fue de 1.18, del lago Lower Sand Creek de 1.31 y del lago Louise de 1.77. Los valores del indicador de nivel tres (invertebrados en tejidos de trucha) en el lago Louise, los lagos Lower y Upper Sand Creek y el lago Trappers variaron según el tipo de tejido. En los cuatro lugares de Colorado, el rango de las funciones de transferencia trófica en el hígado de la trucha fue de 2.31–5.25, óvulo-ovario de 1.30–2.64, y músculo epaxial de 0.28–1.08. Propusimos escenarios no lineales de exposición a la red alimentaria para tres lagos subalpinos. Comparamos las funciones de transferencia trófica de Colorado en las truchas con las de las truchas de río de los lugares lénticos de Se-richer en British Columbia, Canadá. Concluimos que las concentraciones históricas (50 años o menos) de los sedimentos superficiales podían utilizarse para generar coeficientes de fragmentación adecuados en lagos oligotróficos de montaña. Las concentraciones de selenio en el contenido del estómago parecieron ser representativas de una variedad de invertebrados transmitidos por la dieta de la trucha.

The Importance of Phenology and Thermal Exposure to Early Life History Success of Nonnative Smallmouth Bass in the Yellowstone River

AbstractKnowledge of potential spread by introduced species is critical to effective management and conservation. The Smallmouth Bass Micropterus dolomieu is an example of a fish that has been introduced globally, often spreads after introduction, and has substantial predatory impacts on fish assemblages. Nonnative Smallmouth Bass in the free‐flowing Yellowstone River, Montana, have expanded from warmer, downstream sections of river into colder, upstream sections containing socio‐economically valuable trout fisheries. We sought insight into mechanisms controlling upstream spread by evaluating whether progressively colder upstream climates physiologically constrained successful recruitment by limiting age‐0 growth and preventing overwinter survival (i.e., population establishment). We documented the phenology, growth, and overwinter survival of age‐0 Smallmouth Bass across a temperature gradient leading to their upstream extent in the Yellowstone River. The upstream extent of population establishment did not appear limited by water temperature alone. Age‐0 body size at the onset of winter did not differ significantly between colder, upstream reaches and warmer, downstream reaches. Instead, the earlier hatch timing exhibited by some age‐0 individuals in upstream sections allowed them to experience longer growing seasons than many individuals in downstream sections. This counter‐intuitive hatching phenology mediated much of the expected decreases in growth in colder, upstream climates. Furthermore, evidence of successful overwinter survival and simulations of age‐0 starvation mortality indicated that age‐0 individuals at the upstream extent of their distribution successfully recruited to the age‐1 year‐class during four consecutive years. However, age‐0 individuals were rare or absent throughout the uppermost upstream distribution of adults, suggesting that something other than temperature limits or discourages reproduction farther upstream. Taken together, our results suggest that Smallmouth Bass have not yet reached the thermal limit of their upstream distribution in the Yellowstone River and that future spread may challenge fisheries managers tasked with management of coldwater trout fisheries in this river.

The Diet of Two Sympatric Great Cormorant Phalacrocorax carbo Subspecies Wintering at Freshwater Fishery Sites in England and Wales

The recent increase in Cormorant numbers in the UK and the increasing use of inland feeding sites by the birds have created conflicts at many freshwater fisheries. Information on the prey composition of Cormorants foraging at such sites is important in understanding these conflicts and in providing a sound basis for management. Two subspecies of Great Cormorant, the continental subspecies Phalacrocorax carbo sinensis and the Atlantic subspecies Phalacrocorax carbo carbo occur in the UK and forage sympatrically. This study presents information on the winter diet of over 1400 Cormorants shot at inland fishery sites over an eleven-year period. A wide range of prey species were identified, but five fish species compromised almost 80% of the prey items recorded by number, and most prey items were small (≤10 cm). Dietary differences, in terms of the species, sizes and number of fish consumed, were apparent between birds of different sex and subspecies, consistent with the differing sizes of the birds. The largest birds (male P. c. carbo) tended to consume fewer, larger fish and the smallest birds (female P. c. sinensis) more, smaller items. Bird size also appears to influence foraging site selection, with male P. c. carbo more likely to forage on fisheries, such as put-and-take trout fisheries, where larger prey items were available.

Spatial and Temporal Distribution and Habitat Selection of Native Yellowstone Cutthroat Trout and Nonnative Utah Chub

AbstractHenrys Lake, Idaho, is a renowned trophy trout fishery that faces an uncertain future following the establishment of Utah Chub (UTC) Gila atraria. Utah Chub were first documented in the lake in 1993 and have become abundant over the past two decades. Little is known about the ecology of UTC, but they typically have negative effects on salmonids in systems where they have been introduced. We sought to fill knowledge gaps in UTC ecology and provide insight on potential interactions with Yellowstone Cutthroat Trout (YCT) Oncorhynchus clarkii bouvieri. Ninety‐four YCT and 95 UTC were radio‐tagged in spring 2019 and 2020 to better understand potential interactions between YCT and UTC in Henrys Lake. Fish were located via mobile tracking and fixed receivers from June to December 2019 and 2020. In June of both years, YCT and UTC were concentrated in nearshore habitats. As water temperatures increased, UTC were documented in deeper water (mean ± SD = 3.6 ± 1.4 m) and YCT became more concentrated in areas with cold water (e.g., mouths of tributaries, in‐lake springs). In July and August, large congregations of UTC were observed. Yellowstone Cutthroat Trout were detected in tributaries from June to August, but no UTC were detected in the tributaries. By late fall (November–December), YCT were located along the shoreline and UTC were detected in the middle of the lake. Both YCT and UTC were observed in areas with dense vegetation. Macrophytes likely provided a food source for UTC and cover from predators for both species. Locations of YCT were negatively related to warm water temperatures, whereas UTC were positively associated with warm water temperatures. Results from this research fill knowledge gaps in UTC and YCT interactions as well as provide valuable insight on the ecology of UTC and adfluvial Cutthroat Trout populations. Furthermore, distribution patterns and habitat selectivity of YCT and UTC in Henrys Lake can be used to inform management decisions for fishery improvement and YCT conservation.

Population Dynamics and Harvest Management of the Bonneville Cutthroat Trout Fishery in Bear Lake, Idaho–Utah

AbstractLand‐use disturbances and associated losses in habitat quantity and quality negatively affected the Bonneville Cutthroat Trout (BCT) Oncorhynchus clarkii utah population in Bear Lake, Idaho–Utah, in the early 1900s. Bear Lake BCT follow an adfluvial life history strategy, and without access to suitable spawning habitat, the population of wild BCT was nearly extirpated by the early 1950s. In response to this decline, supplementation of the population with hatchery BCT began in 1973. Production of wild BCT was minimal until conservation efforts shifted towards improving fish habitat and access to spawning tributaries. In 2002, only 5% of the population consisted of wild fish; by 2017, nearly 70% of BCT in annual population surveys were wild. As a result, rule changes have been proposed to allow for regulated harvest of wild BCT. However, gaining a comprehensive understanding of the population dynamics of BCT in Bear Lake is critical before changes are made to management of the fishery. The objectives of this study were to describe the population dynamics of wild and hatchery BCT in Bear Lake and evaluate different management options. We evaluated population demographics of hatchery and wild BCT in Bear Lake and used age‐structured population models to assess a variety of management scenarios associated with wild fish harvest regulations (e.g., bag limits). Bonneville Cutthroat Trout grew at relatively fast rates, and females began to mature at age 5. We observed considerable differences in the length and age structure of the hatchery population (i.e., exploited) versus the wild population (i.e., unexploited) of BCT. In general, BCT in Bear Lake were larger and older than Cutthroat Trout O. clarkii in other systems. The current rate of exploitation for hatchery BCT was estimated as 0.27 (i.e., two‐fish daily limit). If the limit were changed to a six‐fish daily limit, the rate of exploitation would be approximately 0.47. A yield‐per‐recruit model evaluating spawning potential ratio indicated that a limit of two wild fish would be a sustainable level of exploitation, whereas a six‐wild‐fish limit would result in recruitment overfishing. This research has provided baseline population dynamics of BCT in Bear Lake that will provide insight for future monitoring efforts. Under current conditions, allowing harvest of either origin BCT in Bear Lake would satisfy angler values while ensuring the persistence of an ecologically and recreationally important population.

The impact of the COVID-19 pandemic on a recreational rainbow trout (Oncorhynchus mykiss) fishery.

There has been a recent flurry of publications describing the potential effects of the COVID-19 pandemic on both commercial and recreational fisheries. As of yet, studies have only provided insights from researchers or industry experts detailing perceived consequences, or from survey data indicating modifications in angler activity levels and behaviours. Using real recreational fisheries data from an ongoing radio telemetry study (2018–present), we explored changes in the relative exploitation rates of rainbow trout (Oncorhynchus mykiss; Walbaum 1792) in the Saugeen River, Ontario, a tributary to Lake Huron, before compared to during the pandemic. Restrictions on site access that affected the implementation of important management activities that usually support this popular fishery are also discussed. During the initial phase of complete public lock-downs imposed during spring 2020, angler exploitation rates decreased to half that reported prior to the pandemic. Fishway operations were temporarily suspended and hatchery efforts were interrupted. Once restrictions began to ease in fall 2020, there was an eight-fold increase in overall exploitation rate and a four and a half-fold increase in harvest rate compared to seasons prior to the pandemic. While the full impact of the ongoing pandemic on the Lake Huron fishery is not likely to be fully realized for several years, the potential effects on future return run sizes may need to be considered by fisheries managers monitoring trends in population escapement.

Population Dynamics of Yellowstone Cutthroat Trout in Henrys Lake, Idaho

Abstract Yellowstone Cutthroat Trout (YCT) Oncorhynchus clarkii bouvieri is a species with significant ecological and recreational value. In many YCT fisheries, managers are tasked with balancing angler expectations and fish conservation. Henrys Lake supports a popular trophy trout fishery, but the increase of nonnative Utah Chub Gila atraria has caused concern for YCT. We summarized long-term trends in abundance, length structure, body condition, and growth of YCT to evaluate the effect of Utah Chub. Additionally, we investigated abiotic and biotic factors influencing YCT. We examined archived hard structures to provide a comprehensive evaluation of changes in age and growth of YCT in the system. We used stocking records and catch rates of Utah Chub and trout in Henrys Lake as covariates to explain changes in YCT catch rates and growth. Catch rates varied from 1.5 to 15.4 YCT per net night during the 2002 to 2020 sampling period, but we did not identify consistent patterns. Length structure was consistently dominated by stock- to quality-length fish, and we captured few fish >600 mm in total length. Relative weight of YCT was decreased from a mean ± standard deviation (SD) of 115.9 ± 16.5 in 2004 to 93.2 ± 8.2 in 2020. The age of YCT varied between 1 and 11 years; fish that we captured during 2010 to 2020 were the oldest. The majority of fish that we sampled were age 4 and younger. Total annual mortality of age-2 and older YCT was higher than other Cutthroat Trout populations (i.e., 0.70 during 2002 to 2010 and 0.60 during 2011 to 2020). Based on regression models, we identified positive relationships between catch rates of YCT, Brook Trout Salvelinus fontinalis, and Rainbow Trout Oncorhynchus mykiss × YCT hybrid trout. We observed negative relationships between growth of YCT and abundance of Utah Chub and Brook Trout. Although we identified negative relationships, YCT growth in recent decades is as fast as or faster than earlier time periods. Results from this research suggest that major changes in YCT population dynamics are not evident over the last 20 years. This study provides insight into the factors influencing an adfluvial trout population. In particular, results from this research may be useful for managers of systems where Utah Chub have been introduced.

Beauty and the beast – trout and treatment plant co-exist

Ranked in the top five trout fisheries in the world, Bull Shoals fishery in Arkansas is worth US$705 million annually. Beautiful Bull Shoals is also home to a water and wastewater treatment plant and the two happily co-exist in the same idyllic setting.