Harvest Regulations Research Articles

Exploitation and catch and release of salmonids in Idaho high mountain lakes

AbstractObjectiveHistorically, most high mountain lakes in western North America were devoid of fish, but during the past century, many have been stocked with salmonids to diversify angling opportunities. Basic information on harvest and catch and release (C–R) for high mountain lake fisheries is lacking, as is information on factors influencing catch in such settings; our objectives were to fill these knowledge gaps.MethodsUsing angling gear, we captured and implanted T‐bar anchor tags into 1163 salmonids of various species (fish of wild origin or hatchery fish stocked as fry; they could not be distinguished) in 103 high mountain lakes scattered across Idaho. Angler‐reported tag returns were used to estimate annual rates of exploitation and C–R, and a model selection approach was used to investigate factors influencing the angler catch of tagged fish.ResultAnglers reported the catch of 125 tagged fish from 52 different lakes. The mean number of days at large for reported fish was 318 days, with a range of 1 to 1465 days. Annual exploitation was 5.8 ± 7.1% (mean ± 90% confidence interval), the annual C–R rate was 8.5 ± 8.5%, and total annual catch (i.e., exploitation plus C–R) was 14.2 ± 11.0%. Of the predictive factors that we investigated, the likelihood of a fish being caught by an angler was negatively associated with hiking distance and positively associated with shoreline development index and fish length.ConclusionOur results indicate that exploitation of salmonids in Idaho high mountain lakes is low even with liberal (six‐fish daily bag limit) harvest regulations. Consequently, angler harvest is unlikely to be substantively affecting the abundance or size structure of salmonid populations in these lakes. Continued tagging would improve the precision of exploitation and C–R estimates, especially for comparisons among species.

Human Behavior and Harvest Regulations: Challenges and Opportunities for Fisheries Managers

Harvest regulation is one of the primary tools that natural resource managers use to manage exploited fish and wildlife populations. Unfortunately, the desired results of harvest regulations are frequently not realized. We contend that a broader and more thorough understanding of anglers could improve the success of harvest regulations. Using a case study from an interstate U.S. fishery for Walleye Sander vitreus, we demonstrate the counterintuitive responses anglers exhibited to differing Walleye harvest regulations. Three possible reasons are explored, using theories from social–science disciplines, to explain why anglers released a greater proportion of larger Walleye under a more liberalized harvest regulation: (1) harvest regulations serving as goals for anglers, (2) resolution of cognitive dissonance provided by restrictive harvest regulations, and (3) the perceived “value” assigned to specific fish or wildlife entity by harvest regulations. We conclude by discussing how taking an interdisciplinary approach (e.g., sociology, psychology, economics) to understanding angler behavior could be an exciting frontier for fisheries management and how this approach specifically holds promise for improving the success of harvest regulations.

Impact of hook choice, fish size, and water temperature on hooking depth, injury, and postcapture physiology in Channel Catfish

AbstractObjectiveCatch‐and‐release angling is an oft‐practiced conservation tool involving the release of captured game fish either due to harvest regulations or conservation ethic on the part of the angler. Central to this practice is the assumption that released fish survive; however, a large body of work has shown that postrelease mortality can occur, especially if fish are injured during the capture process. In this study, we examined hooking location, bleeding, injury rates, and postcapture physiology in Channel Catfish Ictalurus punctatus, a popular game fish species.MethodsA total of 83 Channel Catfish were angled from a lake in southern Illinois using conventional rod‐and‐reel techniques with one of four hook types (J‐hook, shiner, circle, and octopus). Captured fish were then assessed for hooking depth, bleeding, and injury. Subsequently, a subset of 40 fish were additionally held for 4 h in submerged totes before being tested for reflex responsiveness and undergoing a blood biopsy for glucose and lactate levels.ResultCircle and octopus hooks reduced hooking depth in Channel Catfish compared with J‐hooks and tended to reduce postcapture bleeding as well. Postholding physiological results showed no effect of hook type on blood lactate or glucose levels, and reflex impairment was very rare (only a single fish was impaired for any reflexes 4 h postcapture).ConclusionOverall, the results of this study suggest that the use of circle hooks reduce the likelihood of deep hooking and injury in Channel Catfish, though Channel Catfish, at least in the short term, were physiologically resilient to the effects of capture.

Nonnative Smallmouth Bass in the Snake River, Idaho: Population Dynamics, Demographics, and Management Options

Abstract The Snake River in Idaho, USA, supports a popular sport fishery for nonnative Smallmouth Bass Micropterus dolomieu, but there are limited studies on the population dynamics of this introduced species in Idaho and other water systems in the western United States. The purpose of this study was to describe the population dynamics and demographics of Smallmouth Bass in the Snake River, Idaho. In total, we sampled 4,929 Smallmouth Bass during electrofishing surveys on the Snake River (separated into nine segments) and three major tributaries (Boise, Payette, and Weiser rivers). We estimated age for 1,869 Smallmouth Bass sampled from the Snake River (n = 1,433) and three tributaries (n = 436). Catch-per-unit-effort for all nine segments combined on the Snake River was 36.6 fish/h (±4.4 SE). In the tributaries, catch-per-unit-effort varied from 43.6 to 125.0 fish/h. Relative weight of all Smallmouth Bass varied from 86 to 107, indicating that fish were in relatively good body condition. Fish in the system grew fast, with relative growth index values often near or exceeding 100 for all age classes. Total annual mortality for the Snake River was 45.1 ± 0.7%, and it was 36.8–40.5% in the tributaries. Furthermore, we estimated exploitation to be 5.3% (90% CI; ±2.2%) for the Snake River and tributaries combined. We used a yield-per-recruit population model to evaluate the effects of varying minimum length limits on the fishery. With the observed population demographics and exploitation rates, increasing the current minimum length limit from 305 mm to 356 or 406 mm would probably have little influence on the number of Smallmouth Bass available to anglers. However, increasing the length limit would result in reduced biomass available for harvest. The potential for recruitment overfishing was minimal for all minimum length limits and levels of exploitation. As such, changes to current harvest regulations do not appear warranted. Our findings provide important information on the population dynamics of Smallmouth Bass that can be useful in evaluating their management across Idaho and in similar systems in western North America.

Behavioural responses of brown bears to roads and hunting disturbance.

Harvest regulations commonly attenuate the consequences of hunting on specific segments of a population. However, regulations may not protect individuals from non-lethal effects of hunting and their consequences remain poorly understood. In this study, we compared the movement rates of Scandinavian brown bears (Ursus arctos, n = 47) across spatiotemporal variations in risk in relation to the onset of bear hunting. We tested two alternative hypotheses based on whether behavioural responses to hunting involve hiding or escaping. If bears try to reduce risk exposure by avoiding being detected by hunters, we expect individuals from all demographic groups to reduce their movement rate during the hunting season. On the other hand, if bears avoid hunters by escaping, we expect them to increase their movement rate in order to leave high-risk areas faster. We found an increased movement rate in females accompanied by dependent offspring during the morning hours of the bear hunting season, a general decrease in movement rate in adult lone females, and no changes in males and subadult females. The increased movement rate that we observed in females with dependant offspring during the hunting season was likely an antipredator response because it only occurred in areas located closer to roads, whereas the decreased movement rate in lone females could be either part of seasonal activity patterns or be associated with an increased selection for better concealment. Our study suggests that female brown bears accompanied by offspring likely move faster in high-risk areas to minimize risk exposure as well as the costly trade-offs (i.e. time spent foraging vs. time spent hiding) typically associated with anti-predator tactics that involve changes in resource selection. Our study also highlights the importance of modelling fine-scale spatiotemporal variations in risk to adequately capture the complexity in behavioural responses caused by human activities in wildlife.

Genetic analysis of harvest samples reveals population structure in a highly mobile generalist carnivore.

Delineating wildlife population boundaries is important for effective population monitoring and management. The bobcat (Lynx rufus) is a highly mobile generalist carnivore that is ecologically and economically important. We sampled 1225 bobcats harvested in South Dakota, USA (2014-2019), of which 878 were retained to assess genetic diversity and infer population genetic structure using 17 microsatellite loci. We assigned individuals to genetic clusters (K) using spatial and nonspatial Bayesian clustering algorithms and quantified differentiation (F ST and ) among clusters. We found support for population genetic structure at K = 2 and K = 4, with pairwise F ST and values indicating weak to moderate differentiation, respectively, among clusters. For K = 2, eastern and western clusters aligned closely with historical bobcat management units and were consistent with a longitudinal suture zone for bobcats previously identified in the Great Plains. We did not observe patterns of population genetic structure aligning with major rivers or highways. Genetic divergence observed at K = 4 aligned roughly with ecoregion breaks and may be associated with environmental gradients, but additional sampling with more precise locational data may be necessary to validate these patterns. Our findings reveal that cryptic population structure may occur in highly mobile and broadly distributed generalist carnivores, highlighting the importance of considering population structure when establishing population monitoring programs or harvest regulations. Our study further demonstrates that for elusive furbearers, harvest can provide an efficient, broad-scale sampling approach for genetic population assessments.

Modeling Blue Crab (Callinectes sapidus) Larval Transport and Recruitment Dynamics in a Shallow Lagoon‐Inlet‐Coastal Ocean System

AbstractBlue crab (Callinectes sapidus) supports lucrative Mid‐Atlantic crustacean fisheries and plays an important role in estuarine ecology, so their larval transport and recruitment dynamics in the Maryland Coastal Bays system were investigated using simulated and observed surface drifters. Relative contributions of winds, tides, density gradients, and waves to larval recruitment success were identified during the spawning season, particularly under hurricane conditions in 2014. Based on temperature (e.g., 19–29°C) and salinity conditions (e.g., 23–33 PSU), particles representing virtual blue crab larvae were released into the model domain from early June to late October 2014. During the spawning season, variations in the larval recruitment success caused by wind speed and direction, tides (e.g., affecting through inlets), density gradients (e.g., salinity variations), and surface gravity waves were 17%, 4%, −9%, and 17%, respectively. During Hurricane Arthur (2014), variability of self‐recruitment success caused by density gradients are negligible while by other three factors are comparable at 3%–4%. Surface drifter experiments support the modeling results that larval recruitment success is strongly associated with the coastal circulation. The high (low) self‐recruitment success in the Assawoman and Chincoteague Bays (Sinepuxent Bay) is related to the locally weak (strong) circulation; released larvae escape from inlets are likely recruited to southern Fenwick and northern Assateague Islands, and the coastal regions outside the Chincoteague Inlet. Understanding physical factors influencing larval recruitment success helps resource managers make informed decisions about habitat restoration and harvest regulations, in addition to seafood‐related food security.

Effects of a minimum length limit on saugeye population and fishery characteristics in Ohio reservoirs

AbstractObjectiveWe evaluated the effect of a 381‐mm minimum length limit (MLL) on saugeye (female Walleye Sander vitreus × male Sauger S. canadensis) population and fishery characteristics implemented in Ohio reservoirs in 2011.MethodsUsing a before‐after–control‐impact study design (n = 6 control populations and n = 11 impact populations that received the MLL), we compared total CPUE, age‐2+ CPUE, proportional stock density‐harvestable (381‐mm), and length at age 2 (to index growth) determined from standardized gill‐net surveys and saugeye angler effort, catch rate, harvest rate, length of saugeye at harvest, yield, and satisfaction obtained from standardized creel surveys.ResultWe found evidence that the 381‐mm MLL led to an increase in age‐2+ CPUE but had no effect on other saugeye population metrics. In the regulation reservoirs, harvest rates declined following MLL implementation. Total length of harvested saugeye did not increase significantly in response to the MLL, and combined with decreased harvest rates, yield was suppressed in the regulation reservoirs relative to the control reservoirs. However, over 90% of anglers reported that they were satisfied with the MLL during creel surveys.ConclusionDespite marginal influence on saugeye populations and failure to increase yield, anglers supported the MLL. Our results suggest that the effects of harvest regulations may be marginal, and managers should consider the nuances of angler satisfaction in regulation decisions.

Moose and white‐tailed deer mortality peaks in fall and late winter

AbstractThe Grand Portage Band of Lake Superior Chippewa manages for sustainable subsistence harvests of moose (mooz; Alces alces) and white‐tailed deer (waawaashkeshi; Odocoileus virginianus). Moose populations in northern Minnesota, USA, are declining, which may necessitate alterations to Indigenous subsistence practices. Moose and deer exhibit seasonal behaviors such as altered space use and movement strategies, to which gray wolves (ma'iingan; Canis lupus) and humans may adapt, resulting in seasonal mortality patterns. Identifying periods of increased moose and deer vulnerability is important for achieving tribal conservation objectives. We assessed seasonal cause‐specific mortality of adult moose (2010–2021) and deer (2016–2022) fitted with global positioning system collars on and near the Grand Portage Indian Reservation (Gichi Onigaming; GPIR) in Minnesota and hypothesized mortality risk would be influenced by species‐specific space use patterns and weather. We estimated survival rates and mortality risk using time‐to‐event models. We recorded 42 moose mortalities (17 health issues, 8 predations, 4 subsistence harvests, 13 unknown causes) and 49 deer mortalities (26 predations, 13 harvests, 4 other causes, 6 unknown causes). Mean annual moose survival was 83.2%, and mortality risk peaked during late winter (~25 April) and fall (~8 October). Mean annual deer survival was 48.0%, and mortality risk peaked during late winter (~25 March) and during their fall migration period (~11 November). Mortality timing coincided with transitions between space use states (i.e., periods of spatial stability), suggesting ungulates are at greater risk during these transitional periods, though movement strategy (i.e., resident vs. migratory) did not influence mortality risk. Further, increased winter severity corresponded with increased deer mortality. We observed similar temporal peaks in mortality risk when harvest mortalities were censored, suggesting our observed seasonal mortality peaks occur naturally despite harvest comprising most fall deer mortality. Our results can inform population models and harvest regulations by identifying periods of mortality risk on GPIR under Anishinaabe principles of seventh‐generation conservation planning.

American woodcock migration phenology in eastern North America: implications for hunting season timing

AbstractUnderstanding the phenology of migration is fundamental to management of migratory gamebirds, in part because of the role migratory timing plays in setting harvest regulations. Migratory timing is particularly important for determining appropriate dates for hunting seasons, which may be selected to coincide with major periods of migration, according to local management objectives. We used global positioning system (GPS)‐transmitters to track American woodcock (Scolopax minor), characterize the timing of woodcock migration, and identify sources of variation in timing relative to current hunting season structures in eastern North America. We captured 304 woodcock in 3 Canadian provinces and 12 states from 2017 to 2020, primarily within the Eastern Woodcock Management Region. Using locations collected every 1.7 days on average, we assessed whether initiation, termination, or stopover timing of woodcock migration during fall and early spring varied geographically, differed among age and sex classes, or was influenced by individual body condition. During fall, woodcock migrating from summer use areas farther north and west (e.g., Ontario, Quebec, Canada) initiated and terminated migration earlier than woodcock migrating from areas farther south and east (e.g., Rhode Island, USA). Adult woodcock made multiday stopovers that were 3 days longer on average than juveniles and females made more stopovers on average (8.0 stopovers) compared to males (6.1 stopovers). During the onset of spring migration, woodcock that wintered farther west initiated migration before birds that spent the winter farther east, and males initiated migration on average 6 days earlier than females. Under the current 45‐day harvest regulatory framework in the United States, hunting seasons in northern breeding and southern wintering areas are generally consistent with migration phenology. At more intermediate latitudes, however, periods of migration are generally longer than 45 days, resulting in many circumstances where migrating woodcock are present during periods when hunting seasons are closed. Managers in mid‐latitude states could consider opening hunting seasons later, allowing hunters to harvest more migrant woodcock.

Duck hunters and difficulty complying with harvest regulations

AbstractDue to the steady decline of duck hunter participation, several studies have investigated means to bolster the duck hunter population. Researchers and wildlife professionals have assumed that simpler regulations would attract new and unconfident hunters to participate in duck hunting. In light of this, we sought to identify what portion of the duck‐hunting population had difficulty understanding species‐specific bag limits or complying with species‐specific bag limits in the field. We also sought to describe hunters who had difficulty complying with specific bag limits and how their difficulties were associated with elements related to demography, attitude, and behavior. We found most hunters had no difficulty understanding (82%) or complying with (74%) species specific bag limits, but flyway (χ2 = 35.06, P < 0.01), number of ducks harvested (χ2 = 9.76, P < 0.01), number of years hunted (χ2 = 9.20, P < 0.01), and gender (χ2 = 4.14, P < 0.05), were important to predicting hunter difficulty with compliance. Hunters who can overcome their difficulties understanding and complying with species‐specific bag limits may be more likely to be integrated into the duck hunting culture, and more likely to continue duck hunting in the future. More species identification tools and fewer species‐specific bag limits may be appropriate for the 18% of the duck hunter population who indicated that bag‐specific regulations were difficult to understand and the 26% who indicated that it was difficult to comply with species‐specific bag limits in the field. A closer look may be warranted for how the trade‐offs associated with the combination of species‐specific bag limits in combination with the variety of duck season zone and split options states employ, license/stamp requirements, area‐specific regulations, and trespass laws may influence duck hunter experiences.

How diverse is the toolbox? A review of management actions to conserve or restore coregonines

Over the past centuries, coregonines have been exposed to a range of stressors that have led to extinctions, extirpations, and speciation reversals. Given that some populations remain at risk and fishery managers have begun restoring coregonines where they have been extirpated, we reviewed the primary and gray literature to describe the diversity of coregonine restoration or conservation actions that have been previously used. Although stocking of hatchery-reared fish has been commonly used for supplementing existing coregonine fisheries, we considered stocking efforts only with specifically conservation or restoration goals. Likewise, conservation-driven efforts of translocation were not widespread, except in the United Kingdom for the creation of refuge populations to supplement the distribution of declining stocks. Habitat restoration efforts have occurred more broadly and have included improving spawning habitat, connectivity, or nutrient concentrations. Although harvest regulations are commonly used to regulate coregonine fisheries, we found fewer examples of the creation of protected areas or outright closures. Finally, interactions with invasive species can be a considerable stressor, yet we found relatively few examples of invasive species control undertaken for the direct benefit of coregonines. In conclusion, our review of the literature and prior Coregonid symposia revealed relatively limited direct emphasis on coregonine conservation or restoration relative to more traditional fishery approaches (e.g., supplementation of fisheries, stock assessment) or studying life history and genetics. Ideally, by providing this broad review of conservation and restoration strategies, future management efforts will benefit from learning about a greater diversity of potential actions that could be locally applied.

Sex and season influence behaviour and physiology of lake trout following angling.

Catch-and-release angling exposes fish to challenges that may result in sub-lethal effects or mortality. Lake trout (Salvelinus namaycush) undergo high rates of release because of size-based harvest regulations or voluntary angler behaviour. Here, we examine short-term impairment in lake trout angled during the summer (n = 74) and fall spawning period (n = 33) to inform best practices for angling. Immediately following capture or 0.5h post-capture, fish underwent reflex and barotrauma assessments, and a small blood sample was collected. Fish were also fitted with an externally mounted biologger equipped with depth, temperature and tri-axial acceleration sensors, that was tethered to allow retrieval of the logger after 14min. In the summer, reflex impairment and barotrauma at 0 and 0.5h were significantly correlated. Loss of orientation and bloating were the most observed indicators. Larger fish and those captured at increased depth had higher barotrauma scores, while prolonged fight times decreased the barotrauma score regardless of sampling time. Plasma cortisol, lactate and glucose increased 0.5h after capture, and extracellular and intracellular pH decreased, all signs that angling was inducing a metabolic response. However, no relationships were found between blood indices and mortality (18.9%). The time required to reach maximum depth after release was longer for fish with increased air exposure but shorter for those with longer fight times. During the fall, fish displayed no mortality or reflex impairment. Anal prolapse was the most observed indicator of barotrauma but only observed in females. Blood indices were most altered 0.5h after capture, with increased cortisol values for fish that were female, particularly large or captured at deeper depth. Locomotor activity was highest for males and increased with depth. Together, our findings suggest that the effects of catch-and-release angling may be dependent on several factors, including sex, season and angling depth.

Cash Economy and Store-Bought Food Biases in Food Security Assessments of Inuit Nunangat

Researchers, community organisations, and Inuit leaders increasingly question the suitability of methods to assess the prevalence of food insecurity in Inuit Nunangat (the Inuit homeland in Canada). Of particular contention is the United States Department of Agriculture’s (USDA) Household Food Security Survey Module (HFSSM), applied in modified form as part of Health Canada’s nationwide Canadian Community Health (CCHS) and Aboriginal Peoples Surveys. The 18-question HFSSM is the primary survey tool used by the Government of Canada to assess food security prevalence, yet the Module asks only about the affordability of store-bought foods (also termed ‘market foods’ elsewhere in literature) when collecting data to designate food security status. This is despite communities in Inuit Nunangat having complex ‘dual’ or ‘mixed’ food systems and foodways: relying on foods harvested from ancestral lands (country foods) in combination with store-bought foods to sustain mixed cash-subsistence economies and diets. Sourcing country foods requires money for the purchase of equipment and machinery. However, they also have numerous access and availability criteria dictated by non-financial factors. In this paper, we explore the problem of the monetary bias (the focus on an individual or household’s ability to purchase foods) in the HFSSM and discuss the knock-on effects of using monetary metrics as the sole means of measuring and monitoring food security in dual food environments. We contend that relying on monetary access as a measure presents an incomplete picture of the reality of food insecurity in Inuit Nunangat. Presently, there is little consideration of the nuance of social norms and cultural values that govern dual food systems or the importance of less tangible non-financial factors that might affect food access (e.g. knowledge of where and how to harvest and maintain machinery, suitable environmental conditions for travel, conducive harvest regulations, social relationships, and ecological stability). Ultimately, this contributes to restricted policy-level understandings of what it means to ensure stable, culturally adequate, and just food systems, and limits self-determination in northern food environments.

Seasonal spatial ecology of Lake Trout in Lake Erie

AbstractObjectiveLake Trout Salvelinus namaycush are native coldwater apex predators that play an important role in maintaining ecosystem functionality and diversity in the Laurentian Great Lakes. Following population collapses, rehabilitation efforts were widely initiated in the Great Lakes to reestablish self‐sustaining Lake Trout populations. Lake Erie may pose a challenge to these rehabilitation efforts due to limited availability of appropriate oxythermal habitat. Our goal was to investigate seasonal habitat use of adult Lake Trout in Lake Erie to inform management and rehabilitation efforts.MethodsWe used acoustic telemetry in Lake Erie, which was equiped with a lake‐wide acoustic receiver grid, to quantify Lake Trout seasonal region occupancy, dispersal distances, bottom depth occupancy, space use extent, and space use overlap.ResultWe found that 32% of fish tagged in the eastern basin and all fish from the western basin dispersed more than 100 km from their tagging location, which represents a greater proportion of the population moving long distances than what has been previously documented in the Great Lakes. During stratification, Lake Trout were detected almost exclusively in the offshore eastern basin in areas where water depth exceeded 25 m. During nonstratified seasons, fish used other regions of the lake, occupying areas of highly variable depths. During fall, most fish tagged in the eastern basin occupied habitat along the southern shore of the eastern basin. Fish tagged in the western basin returned to this region in the fall of subsequent years despite occupying the offshore eastern basin during stratification and having depth occupancy, home range size, and overlap similar to that of eastern basin‐tagged fish. Fish size was positively correlated with receiver depth during winter and spring, and with home range overlap during spring and summer.ConclusionThe results of this study can begin to inform management decisions regarding stocking locations, harvest regulations, and habitat restoration to facilitate the continued rehabilitation of this important native species.

Co-designing management recommendations with stakeholders: A case study about northern pike (Esox lucius) in the southern Baltic Sea

Involving all interest groups, often called stakeholders, is increasingly recognized as a key part of sustainable natural resource management, promoting acceptability and compliance with management decisions. However, there is the difficulty of how to build trust, integrate diverse knowledge bases and account for varying objectives of different stakeholders. We present insights from a fisheries stakeholder process that used structured decision making and participatory modelling in a workshop series over the course of three years to develop management advice for a northern pike (Esox lucius) meta-population inhibiting brackish lagoons of the southern Baltic Sea in Germany. The stock is co-exploited by commercial and recreational fisheries who are in conflict over space and fish and vary in values. We formed and professionally facilitated a stakeholder group composed of 15 representatives of all main interest groups. The workshops generated a shared vision and seven mutually agreed management objectives that combined aspects of biological, ecological, economic, and social sustainability. To meet objectives, the group identified more than 40 management options, revolving around stock monitoring, control and surveillance, knowledge transfer, harvest regulations, habitat management, predator control and pike stocking. Participatory model building provided forecasts on the impacts of selected management options, allowing to transparently examine trade-offs based on quantitative criteria matched to objectives. The process overall led to stakeholder consensus about multiple management tools that the group recommended to government officials for future management reform. Challenges remain as to the communication of irreducible ecological and social uncertainties associated with quantitative predictions. In this context, cognitive maps about cause-and-effect relationships affecting pike were found useful to integrate knowledge and remind about uncertainties. Our case study shows that stakeholder-inclusive approaches using structured decision making and participatory modelling with professional facilitation are time- and planning-intensive, but can promote common system understanding and development of mutually agreed management advice also in heterogeneous stakeholder groups that are often in severe conflict with each other.

Examining the performance of alternative harvest regulations for short-lived taxa: A case study of Florida Bay scallop management

The life history schedule of short-lived species compresses the temporal window available for harvest and exacerbates harvest timing decisions. For annual species whose populations are made up of a single year class, it is challenging yet essential to limit harvest to a level that will allow sufficient spawning escapement to sustain the population. Unexpectedly, intense harvest prior to reproduction could extirpate a population in a single season. Larger-scale commercial fisheries for annual or semelparous species are often managed using sophisticated pre-season abundance forecasts or in-season depletion estimates combined with intensive monitoring of catches and enforcement of catch limits. However, sufficient monitoring and harvest control are rarely feasible in recreational fisheries. We demonstrate the use of an age-structured simulation model to identify robust management regulations for recreational harvest season and bag limits applied to the Florida bay scallop fishery. We compared the outcomes of current harvest regulations with a suite of alternative harvest regulations in a recreational fishery for Florida bay scallops. To account for uncertainty in the stock status and dynamics of the fishery, we evaluated alternative harvest options across three levels of initial stock exploitation and two scenarios for future fishing effort. Our results show that biologically-informed regulations which allowed for more bay scallops to spawn prior to harvest, such as a later harvest season and daily harvest limit increasing over the season, performed well across all treatments and outperformed many of the current regulations when the initial stock state was more exploited, as well as when future effort doubled. These results suggest that (1) harvest regulations that more closely match the biology and life history are likely to perform better for short-lived, annual taxa than simpler regulations that may not explicitly consider these factors, and (2) simpler regulations can perform well, but require precise, annual monitoring to prevent potentially catastrophic overharvest or costly underutilization.

Estimating recruitment rate and population dynamics at a migratory stopover site using an integrated population model

AbstractConsideration of the full annual cycle population dynamics can provide useful insight for conservation efforts, but collecting data needed to estimate demographic parameters is often logistically difficult. For species that breed in remote areas, monitoring is often conducted during migratory stopover or at nonbreeding sites, and the recruitment rate of new breeding adults can be difficult to estimate directly. Here, we present an integrated population model that uses mark‐resight and count data to estimate survival probability, population growth rate, and recruitment rate for an Arctic‐breeding shorebird of conservation concern, the red knot (Calidris canutus rufa), from data collected during spring stopover in Delaware Bay, USA, from 2005 to 2018. At this site, red knots feed primarily on the eggs of spawning horseshoe crabs (Limulus polyphemus), a legally harvested species. We used this model to estimate the relationship between horseshoe crab abundance and red knot demographics, which informed a recent revision to the framework used to establish horseshoe crab harvest regulations. Our analysis indicates that the red knot population was most likely stable from 2005 to 2018 (average λ = 1.03, 95% credible interval [CRI]: 0.961, 1.15) despite low recruitment rates (average ρ = 0.088, 95% CRI: 0.012, 0.18). Adult survival probability was positively associated with horseshoe crab abundance in the same year (β = 0.35, 95% CRI: 0.09, 0.63), but we found no effect of horseshoe crab abundance two years previously on recruitment of new adults (β = −0.08, 95% CRI: −0.41, 0.38). Our approach demonstrates the utility of integrated population models for understanding population dynamics, even when data are only available from migratory stopover monitoring.

Recreational anglers’ preferences about harvest regulations to protect a threatened freshwater fish in France

A number of freshwater fish particularly migratory species are currently under threat. As the pressure of recreational fishing has intensified, this activity needs to be more regulated to halt the decline of threatened fish stocks. This paper presents results of an economic valuation study of anglers' preferences for a change in the rules applying to Twaite shad fisheries in south-western France. Twaite shad has become a “near-threatened” species, with the same IUCN status as the Atlantic salmon. As shad recreational angling continues to be open access, new regulations are required to limit recreational harvest in support of a management strategy to prevent stock reduction even to foster stock recovery. We combined a deliberative choice experiment with open group discussion to obtain an in-depth understanding of anglers' preferences between two types of traditional regulatory instrument – a license fee or a bag limit. The closure of the fishery served as the reference scenario. The results indicate that the majority of anglers were aware of the decline of Twaite shad stocks. The recreational value of the species remains high, especially for those who already target migratory species. Although econometric estimations show that there are heterogeneous preferences across anglers, there were support for a change toward a bag limit, and an aversion for a high-priced licence fee. The findings also provided two key insights to improve recreational fishing management and preservation policy for threatened species. The communication of observation data on fish stock could not be considered as a sufficient ecological information to ensure threatened species monitoring leads to an effective co-management with anglers' community. Anglers’ aversion to loss can be seen as a behaviour mechanism towards the preservation of the species rather than to its use.

Do anglers and managers think similarly about stocking, habitat management and harvest regulations? Implications for the management of community-governed recreational fisheries

Perceptions about suitable fisheries management directions can differ between anglers and fisheries managers. Opposing beliefs, attitudes and norms about how to manage a local fishery can in turn create conflict. Within a system of community-held local fishing rights, typical for central Europe, the interaction of anglers and local-level fisheries managers is particularly strong and direct because the managers are typically elected members of the local angling communities that are organized in clubs. In this role local fisheries managers are responsible for decisions about management measures, such as stocking or harvest regulations. Our objectives were to assess the perceived objectives, beliefs and attitudes towards a range of management-relevant issues, while contrasting anglers and elected fisheries managers in the context of German fishing clubs. Based on three large mail surveys conducted between 2010 and 2018 and including a total of 3112 anglers and 314 elected fisheries managers from the Federal State of Lower Saxony (north-western Germany) we found that anglers and fisheries managers both supported conservation objectives and held strong pro-stocking beliefs, which was particularly pronounced among anglers. Both groups significantly differed in their pro-ecological beliefs and the perceived functionality of habitat management and harvest regulations relative to fish stocking. Fisheries managers considered habitat enhancement and harvest regulations to deliver greater benefits than stocking compared to anglers. Both groups also differed in their behavioural intention to alter stocking practices, particularly with respect to the stocking of large and adult fish, which was desired by anglers, but on average rejected by fisheries managers in favour of the release of smaller fish. Our work shows that even within the traditional practice of fish stocking, anglers and fisheries managers differ in their perceptions. Engaging in decisions that deviate from the perception of anglers is prone to create conflicts. Harmonization of perspectives maybe possible through joint experiments in fisheries management at the club level, aiming to collectively learn about successes and risks of traditional and novel management approaches.