Fisheries Management Agencies Research Articles

Methods and approach to the interdisciplinary and cross-cultural Alaska Arctic Salmon Workshop: critical self-reflections from fisheries scientists

Redistribution and shifting habitat envelopes are impacting organisms across many taxa, which in turn are impacting Indigenous ways of life. In Arctic Alaska, Pacific salmon are known to have occurred for at least a century, but in recent years appear to be increasingly common. With the goal of holistically understanding and describing these changes in a way that equitably considers Indigenous, local, and western knowledge, we share our experience and methodologies in facilitating the Arctic Alaska Salmon Workshop. We share our perspective, approach, and methods as fisheries natural scientists convening this workshop, which included community-based knowledge holders from the Iñupiat communities of Kotzebue, Point Hope, Utqiaġvik, and Kaktovik, and western scientists and researchers from universities, fishery management agencies, and local community government. After briefly discussing some of the workshop highlights, we conclude with four key takeaways: 1) that the process of co-production of knowledge is an ideal towards which we must strive, but acknowledge we may rarely, if ever, fully achieve, 2) pursuit of the ‘good science’ should guide our work, 3) examination and assessment of assumptions should occur early and often, and 4) Anglanikina! Make sure you have a good time, (Yup’ik).

Development and analyses of stakeholder driven conceptual models to support the implementation of ecosystem-based fisheries management in the U.S. Caribbean.

Fisheries management agencies in the U.S. Caribbean are currently taking steps into transitioning from a single species approach to one that includes Ecosystem Based Fisheries Management (EBFM) considerations. In this study, we developed and analyzed stakeholder-driven conceptual models with seven different stakeholder groups in Puerto Rico and the US Virgin Islands to assess and compare their perceptions of the fishery ecosystem. Conceptual models were developed for each stakeholder group during 29 separate workshops involving a total of 236 participants representing Commercial Fishers, Managers, Academics, Local Businesses, Environmental NGOs, and the Caribbean Fishery Management Council (CFMC) District Advisory Panels (DAPs) and Scientific and Statistical Committee (SSC). Non-Metric Multidimensional Scaling (nMDS) and two-mode social network analysis were used to investigate differences and similarities between stakeholder groups as well as to identify priority ecosystem elements and threats. Results show important variations between stakeholders and islands in terms of their perceived importance of ecosystem components and relationships, which supports the need for collaborative approaches and co-production of knowledge in the United States (U.S.) Caribbean region. Despite this variation, important areas of common concern among stakeholders were identified such as: habitat integrity (e.g., coral reefs), water quality, and influence of recreational fisheries and tourism on marine ecosystems. Findings of this study support the use of stakeholder-driven conceptual models as effective tools to guide decision-making, aid prioritization of data collection, and increase collaboration and cooperation among stakeholders in the context of fisheries management.

Building stewardship capacity through fishers’ knowledge and advocacy in fisheries management: a case study from Southeast Alaska

Local environmental stewardship supports resilience of social-ecological systems through a wide range of actions that benefit both environmental and human wellbeing. Stewardship actions of harvesters have been recognized as an important component in building adaptive capacity of coastal fisheries undergoing change. In Southeast Alaska, where commercial fishing plays a key role in cultures and economies, concerns for local fisheries have arisen from declines in salmon returns, high price variability, and barriers to participation, among other issues. Here, we aimed to understand existing and potential pathways for stewardship actions of small-boat commercial fishers in Juneau, Alaska. We conducted semi-structured interviews with 22 commercial fishers, agency staff, and leaders of seafood associations to document fisher-led stewardship actions and ways that small-boat commercial fishers engage formally and informally with local management, explore the role of fishery management agencies in facilitating collaboration and communication with fishers in the Juneau area, and understand local perspectives on how the stewardship capacities of the fishery system can be better supported. We found that multiple pathways for stewardship exist in commercial salmon and shellfish fisheries, including formal and informal interactions with state fishery management staff and decision-makers, participation in fishing associations and advocacy organizations, knowledge sharing among fishers, and taking personal conservation actions to care for fisheries. We identified areas of relatively low social, financial, and institutional capital that may limit the effectiveness of these stewardship actions. Our findings highlight diverse perspectives of fishery participants on how these stewardship actions might be better supported through policy, advocacy, and collaboration.

Unlocking the Perceptions of Fishing Communities for a Credible and Effective Weather Forecasting and Early-Warning System in Zanzibar, Tanzania

Small-scale fishers are highly vulnerable to the impacts of weather conditions and climate variability, which can significantly affect their livelihoods and safety at sea. This study assessed the small-scale fishers' access and usage of weather forecasts and early warning systems in Zanzibar. It did so by examining the fishing communities' perceptions of the matter and patterns of utilisation of the weather information. It investigated the sources and accessibility of weather forecasts and early warning systems to the fishers. It utilised a descriptive and observational design using qualitative approaches. Data were collected through structured interviews, observation, and focus group discussions with samples of small-scale fishers in six villages in Unguja and Pemba in Zanzibar. The findings show that small-scale fishers in Zanzibar face significant challenges accessing reliable and timely conventional weather forecasts and early warning information. Limited access to communication technologies, including television and smartphones, emerged as a significant barrier. In addition, the utility of modern meteorological information and early warning systems is limited by their perceived unreliability to fishing communities. The fishing communities extensively use traditional weather forecasting methods informed by generations of tradition. Using informal communication channels and telephony services, local communities integrate conventional weather information served through short messaging services with traditional weather prediction systems. The integration provides credible results shared across the communities for collective decision-making on safer fishing practices. These findings are important for Zanzibar's policymakers, fisheries management agencies, and climate service providers. There is a need for the Revolutionary Government of Zanzibar and other stakeholders to deliberate and improve communities' access to reliable weather forecasts and early warning systems for their resilience and sustainable fishing practices. It is also important for the government and other stakeholders to promote integrating indigenous knowledge with scientific forecasting methods for a comprehensive and contextually relevant information framework for small-scale fishers and other consumers.

De-hooking depredation: Exploring multiple fisher perceptions about marine depredation in Florida

Marine depredation involves the removal of or damage to captured fish by predators, and recent evidence suggests it is increasing globally likely due to increasing fishing effort and changes in predator behavior. Anecdotal reports indicate that marine depredation in Florida may be especially severe, given the high number of fishers and predator species. However, the magnitude of marine depredation in Florida and fisher perceptions of these events are poorly understood. We employed a survey of commercial, private recreational, and for-hire saltwater license holders to explore the extent and magnitude of fishing experiences and perceptions related to marine depredation across Florida, highlighting differences among fisher groups using closed- and open-ended survey questions. We found few to no significant differences between fishing sector groups, meaning depredation was prevalent across all locations, gear types, and target species. Most user groups experienced depredation by more than one predator, but sharks and dolphins were reported as the most common predators. Commercial and for-hire operators were more likely to have very negative and negative sentiments toward predators, while private recreational fishers were more likely to view their depredation experiences as neutral. The need for improved management of predators and other fish stocks was expressed across all sectors, especially among commercial fishers. Our results support the growing literature on increased depredation experiences statewide and the need to devise a solution for all marine fisheries users in Florida. We anticipate our exploratory findings to be used as a starting point for researchers and fisheries management agencies to understand fishing sector perceptions and attempt to mitigate negative depredation experiences.

A science and management partnership to restore coregonine diversity to the Laurentian Great Lakes

Similar to many freshwater ecosystems, the Laurentian Great Lakes of North America have undergone numerous anthropogenic stressors resulting in considerable loss of biodiversity and habitat. Among Great Lakes fishes, the coregonine sub-family has endured the most extensive declines, including extinction of several species ( Coregonus johannae, C. alpenae, and C. kiyi orientalis) and at least 10 instances of local extirpations of other species ( C. nigripinnis, C. reighardi, C. zenithicus, C. hoyi, and C. artedi) across all 5 lakes, much of which occurred prior to the 1960s owing to overfishing, interactions with non-indigenous species, and habitat loss. Despite these declines, no federal-, provincial-, or state-mandated actions were ever implemented to conserve coregonine diversity, potentially because so much of the coregonine declines occurred prior to the enactment of federal conservation legislation. Possible explanations for inaction since enactment of that legislation include insufficient data on biological vulnerability or threats, unresolved taxonomy, and limited support from the fishery management agencies and their stakeholders prior to the 2000s. In recent decades, however, several fishery management agencies have undertaken efforts to re-introduce coregonine diversity. These efforts helped lead to development of a science-based framework to restore coregonines that was universally endorsed by fishery managers representing eight U.S. states, four U.S. tribal organizations, and the province of ON, Canada, in May 2018. The basin-wide framework is based on principles of conservation biology and adaptive management. We describe details of its key steps, including planning, restoring, and evaluating, while also describing recent implementation efforts to develop methods, improve available resources, and enhance coordination across the basin. Although our paper describes a regional effort to restore native coregonines, our adaptive-management approach could be used by other multi-agency stakeholders seeking to conserve or restore native fishes.

Kings of the North: Bridging Disciplines to Understand the Effects of Changing Climate on Chinook Salmon in the Arctic–Yukon–Kuskokwim Region

Understanding how species are responding to environmental change is a central challenge for stewards and managers of fish and wildlife who seek to maintain harvest opportunities for communities and Indigenous peoples. This is a particularly daunting but increasingly important task in remote, high‐latitude regions where environmental conditions are changing rapidly and data collection is logistically difficult. The Arctic–Yukon–Kuskokwim (AYK) region encompasses the northern extent of the Chinook Salmon Oncorhynchus tshawytscha range where populations are experiencing rapid rates of environmental change across both freshwater and marine habitats due to global climate change. Climate–salmon interactions in the AYK region are a particularly pressing issue as many local communities have a deep reliance on a subsistence way of life. Here, we synthesize perspectives shared at a recent workshop on Chinook Salmon declines in the AYK region. The objectives were to discuss current understandings of climate–Chinook Salmon interactions, develop a set of outstanding questions, review available data and its limitations in addressing these questions, and describe the perspectives expressed by participants in this workshop from diverse backgrounds. We conclude by suggesting pathways forward to integrate different types of information and build relationships among communities, academic partners, and fishery management agencies.

Tidal migrations of juvenile Sillago spp. in a subtropical intertidal nursery seascape

Context Subtropical intertidal pools on depositional shores are important nursery habitats for smaller juveniles (10- to ~25-mm total length, TL) of commercially important smelt whiting (Sillago spp.), whereas larger juveniles >25 mm TL occupy shallow subtidal habitats at low tide. Aims We investigated the connectivity between lower and upper shore habitats in Moreton Bay. Methods We used funnel camera traps to assess tidal movements of juvenile whiting and compared harpacticoid copepod genera in small juvenile whiting guts caught post-foraging with those sampled from nearby sediments to infer patterns of foraging. Key results Smaller juveniles transited sandy upper-shore habitat at depths from 1.5 to <10 cm and avoided vegetated habitats, whereas larger juveniles moved into mangroves at depths of 15–30 cm on the rising tide. Coullana spp. harpacticoids were found in greater proportions in whiting guts of small juveniles than in the sampled habitats, but were abundant in intertidal pool and mangrove sediments. Conclusions Intertidal sandy habitats are seemingly an important high-tide habitat for smaller juvenile whiting, where they preferentially forage on Coullana spp. Implications Given the broad distribution of smelt whiting in the Indo-Pacific, the protection of such habitats must be addressed by fishery and habitat management agencies for species with similar early nursery requirements.

Guiding principles for integrating stakeholder‐based data into marine fisheries decision‐making with a focus on USA fisheries management

AbstractThe propensity for fisheries management agencies in the United States to collect or request stakeholder‐based data has grown considerably in the last decade. While systems are in place for the review and use of biological data in management, there is far less structure to the integration of non‐economic social data. Here, we present a framework for characterizing the applicability of various forms of social data in regulatory processes, documents, and decisions. The social data landscape is presented as a simple framework for understanding the temporal, spatial, and impact scope of policy actions and how different kinds of social data can inform an array of action types and play important roles in management. We conclude with recommendations for practitioners and managers who seek to incorporate different types of stakeholder input into their processes and provide researchers with guidelines when weighing the trade‐offs of unique methodologies.

Upstream and Downstream Dispersal Behavior of Hard‐ and Soft‐Released Juvenile Atlantic Salmon

AbstractFailure of reintroduction efforts of extirpated populations is thought to be linked to maladaptive behaviors exhibited by captive‐bred individuals in the environment where they are released. Soft‐release conditioning tactics attempt to reduce maladaptive behaviors by providing reintroduced animals an acclimatization period prior to release. We used implanted passive integrated transponder tags and antennae to monitor the spatial and temporal dispersal behavior of captive‐bred Atlantic Salmon Salmo salar that were acclimatized for 6 d prior to release (soft‐release), with fish that were directly released (hard‐release) into East Duffins Creek in Ajax, Ontario, Canada. In total, 232 of the 610 tagged fish (38%) dispersed from the release site. Downstream spatial dispersal did not differ significantly between the hard‐release (32%, n = 98 of 310) and soft‐release fish (30%, n = 91 of 300), but the hard‐release fish were significantly more likely to move upstream (11%) than were the soft‐release fish (3%). Timing of dispersal also significantly differed between the two groups: soft‐release fish were detected dispersing, on average, approximately 15 d earlier than hard‐release fish. These results suggest that soft‐release tactics do affect dispersal behavior, and the findings will be of particular interest to fisheries management agencies that are charged with improving the success for stocking salmonids as part of reintroduction efforts.

Season and Discharge Predict Downstream Emigration Rates for Reservoir Sport Fish Populations

AbstractGiven the importance of reservoir fisheries and the investments made by fisheries management agencies to create and maintain these fisheries, the loss of reservoir‐stocked fish through downstream emigration warrants action to be taken to understand and prevent it. The factors driving emigration of reservoir fish and the measurable effects of emigration on fish population dynamics are not well understood. In this study, we sought to understand the seasonal emigration patterns of two popular sport fish, saugeye (female Walleye Sander vitreus × male Sauger Sander canadensis) and Muskellunge Esox masquinongy, and determine if their annual declines in abundance were correlated with predicted annual emigration rates. We modeled daily emigration probabilities of saugeye and Muskellunge from PIT tag data collected in the dam spillway of an Ohio reservoir. Using data on discharge from previous years, these models were used to estimate annual emigration rates, which were regressed against historical catch data to test whether emigration explained annual cohort declines. Our models showed that downstream emigration from the reservoir occurred primarily during spring for both species, especially during periods of high reservoir discharge. All saugeye and nearly all Muskellunge emigrants were adults, with 13% of tagged adult saugeye and 17% of tagged adult Muskellunge emigrating. Our models predicted historical annual emigration losses (across all age‐classes) as high as 24% for saugeye and 8.6% for Muskellunge. Furthermore, historical annual emigration rates were negatively related to catch rates for both species. These results illustrate that, depending on flow regime and seasonal effects on fish movements, emigration can have measurable effects on reservoir sport fish populations. As such, it is important to understand the factors driving downstream migration and use this understanding to inform decisions on potential mitigation of emigration as well as fish stocking decisions.

Reducing Invasive Species Transport among Recreational Anglers: The Importance of Values and Risk Perceptions

AbstractThe behavioral patterns of recreational anglers are an increasingly common focus of fishery management agencies, particularly due to the unintentional spread of aquatic invasive species. Previous research in this area has focused on understanding stakeholder awareness, use patterns, and beliefs. Although informative, these drivers of behavior are easily shifted by new information and are thus potentially less influential for encouraging long‐term behavior change. There is a pressing need to account for the effects of human values in management of aquatic invasive species because values are a fundamental driver of behavior that changes slowly over time and represents a core basis for angler decision making. Therefore, this study assessed the relationships among values, risk perceptions, and reported aquatic invasive species prevention behavior to inform management decisions aimed at minimizing angler transport of aquatic invasive species. We generated a data set from a mixed‐mode survey of license‐holding recreational anglers from counties adjacent to the Great Lakes in three U.S. states (n = 788). Results from a structural equation model revealed that biospheric values positively predicted social and personal risk perceptions. Personal risk perceptions in turn positively predicted private and public dimensions of reported behaviors related to reducing the spread of aquatic invasive species. Efforts to reduce the spread of aquatic invasive species within the study context would be best served by emphasizing the personal impacts rather than broader social and ecological consequences from biological invasions. Agencies should also shift their attention to thinking about the role of values in explaining how people process and respond to environmental threats and degradation from aquatic invasive species.

Gabor Feature Representation and Deep Convolution Neural Network for Marine Vessel Classification

The Vessel Surveillance System (VSS), a crucial tool for fisheries monitoring, controlling, and surveillance, has been required to use for the reservation of the current depressed state of the world's fisheries by fisheries management agencies. An important issue in the vessel surveillance system is the classification of vessels. However, several factors, such as lighting, congestion, and sea state, will affect the vessel's appearance, making it more difficult to classify vessels. There are two main methods for conventional classifications of vessels: the traditional-based- characteristics method and the convolutional neural networks-used method. In this paper, we combine Gabor feature representation (GFR) and deep convolution neural network (DCNN) to classify vessels. Gabor filters in different directions and ratios are used to extract vessel characteristics to create a new image of vessels, which is DCNN's input. The visible and infrared spectrums (VAIS) dataset, the world's first publicly available dataset for paired infrared and visible vessel images, was used to validate the proposed method (GFR-DCNN). The numerical results showed that GFR-DCNN is more accurate than other methods.

Explaining Channel Catfish Population Characteristics in Ohio Reservoirs

AbstractNorth American fisheries management agencies commit considerable resources to managing reservoir fisheries for Channel Catfish Ictalurus punctatus, which often includes stocking. However, Channel Catfish population characteristics often vary greatly among reservoirs, resulting in variable and unpredictable fishery quality. We sampled Channel Catfish populations in 44 Ohio reservoirs with tandem, baited hoop nets to understand relationships among population characteristics (density, as CPUE from hoop nets; growth, as mean length at age 7; mortality, as total annual mortality from catch‐curve analysis; and size structure, as proportional size distribution), stocking, and the relationships between these characteristics and reservoir size (as surface area), predator density (as Largemouth Bass Micropterus salmoides electrofishing CPUE), and productivity (as chlorophyll‐a concentration). We used multiple linear regression and an information theoretic approach to select the most parsimonious models for explaining observed variation in Channel Catfish density, growth, mortality, and size structure. We found that population density varied greatly among our study reservoirs, and none of our models sufficiently explained variation in density. Reservoir size and the interaction between reservoir size and population density explained the most variation in Channel Catfish growth, but productivity was also important. Small reservoirs (≤101 ha) had low to moderate densities and growth was uniformly slow; however, in larger reservoirs, lower densities resulted in faster growth. Growth increased as productivity increased. Total annual mortality was uniformly low (<0.26) but increased with density. Faster growth led to populations with larger size structures. These outcomes show that the largest Ohio reservoirs (≥406 ha) are the most suitable for supporting populations with fast growth and large size structures. Dense populations (CPUE > 50 Channel Catfish/net set) resulted in slower growth, greater mortality, and poor size structure. Future research to understand natural recruitment in reservoir Channel Catfish populations could be important for explaining variation in density.

Reported capture, fishery perceptions, and attitudes toward fisheries management of urban and rural artisanal, small-scale fishers along the Bahía de Banderas coast, Mexico

Artisanal fishing is a very important activity for the subsistence of coastal inhabitants in Latin American countries. Increasingly, what has traditionally been a rural activity is being enveloped by urban expansion, resulting in urban-based artisanal fishers. We administered 98 questionnaires to artisanal fishers along the Jalisco coast of the Bahia de Banderas, on the Pacific Coast of Mexico. Approximately half of the participants belonged to each of urban (Puerto Vallarta) or rural collectives. The aim of the study was to understand the differences and similarities between urban and rural fishers with respect to demographics, fishing behaviors, assessments of past, current, and future fishing resources, attitudes towards fisheries management, and perceptions of human-environment relationships. The respondents represented an aging demographic with a low level of education. They reported catching 27 different species of fish, primarily of the Family Lutjanidae, although rural fishers reported a greater variety of species captured. Half of the respondents supplement fishing with a second form of income, a trend that is more prevalent in rural fishers. Fishers indicated that fishing was better in the past and predicted it will be poorer in the future; rural fishers were more negative about fishing conditions. Almost all fishers were concerned about the health of fish populations and three-quarters of them felt that fish populations are disappearing. Specific fishing practices were the highest cited problems facing fishing and making changes to these problems was identified to improve fishing. Half the respondents felt that there is conflict between artisanal and commercial sport fishers, but this is more prevalent in urban fishers. Respondents indicated that fishery managers need to do their job (e.g. resource monitoring, enforcement) and apply fisheries laws in order to help improve regional fisheries. Overall, concerns for a future sustainable fishery are reflected in an ecocentric view of humanity and nature by both groups, although it is often statistically greater in urban fishers. These results provide an insight into differences between urban and rural fishers that can be useful for local fisheries collectives, regional and federal fisheries management agencies, as well as global approaches to small-scale fisheries.

Use of remote sensing tools to predict focal areas for sea turtle conservation in the south‐western Atlantic

Abstract Fisheries bycatch of non‐target species in the commercial fleet is a major source of anthropogenic injury and mortality for sea turtles and marine megafauna. The Río de la Plata maritime front (RLPMF) and its adjacent international waters – comprising part of the Argentine and Uruguayan exclusive economic zones, is a highly important fishing ground in the south‐western Atlantic Ocean as well as feeding and development grounds for sea turtles. This paper analyses the distribution of the bottom and pelagic trawling fishery within the RLPMF using information from Vessel Satellite Monitoring System. With this information, areas of highest trawling intensity were defined and further evaluated their overlap with sea turtle habitat‐use areas from available sea turtle satellite tracking information. Results besides identifying high‐susceptibility areas for sea turtle bycatch by the commercial trawler fleet along the RLPMF, provide predictive tools to identify vulnerable areas to interaction of sea turtles and the commercial fishing fleet. Implementation of bycatch mitigation measures, such as reduced fishing effort areas by the Argentine and Uruguayan fisheries management agencies has the potential to benefit the fisheries as well as marine megafauna. Furthermore, there is a need for additional research on the impact that this fleet can have on sea turtles present in the area.

Opportunities for fishery partnerships to advance climate-ready fisheries science and management

Climate change poses unprecedented challenges for fisheries management systems. Increased environmental variability and uncertainty due to climate change are creating shifts in productivity and distribution of fished species, and subsequent social-ecological impacts that require timely implementation of adaptive management strategies. Yet many proposed “climate-ready” fisheries actions – such as integrating climate factors into stock assessments and increasing flexibility in decision-making – either complicate or add to existing responsibilities of fishery managers and strain existing institutions. In the United States, many fisheries management agencies have explicitly acknowledged certain capacity shortfalls and institutional limitations to addressing current and projected impacts of climate change on marine fisheries. Many resource and capacity gaps across the adaptive fisheries management cycle could be filled through more effective fishery partnerships among management agencies, fishing industries, private sector, and academia. Partnership approaches are key to unlocking capacity for achieving climate-ready fisheries yet expanded implementation may require a shift towards a model that empowers and obligates fishery stakeholders to take on expanded roles with appropriate guidelines and oversight, while establishing increased roles for agencies as facilitators and auditors for certain tasks. Building and institutionalizing more effective fishery partnerships to achieve climate-ready fisheries will require clear guidance and enabling conditions.

Correspondence between a recreational fishery index and ecological condition for U.S.A. streams and rivers

Sport fishing is an important recreational and economic activity, especially in Australia, Europe and North America, and the condition of sport fish populations is a key ecological indicator of water body condition for millions of anglers and the public. Despite its importance as an ecological indicator representing the status of sport fish populations, an index for measuring this ecosystem service has not been quantified by analyzing actual fish taxa, size and abundance data across the U.S.A. Therefore, we used game fish data collected from 1,561 stream and river sites located throughout the conterminous U.S.A. combined with specific fish species and size dollar weights to calculate site-specific recreational fishery index (RFI) scores. We then regressed those scores against 38 potential site-specific environmental predictor variables, as well as site-specific fish assemblage condition (multimetric index; MMI) scores based on entire fish assemblages, to determine the factors most associated with the RFI scores. We found weak correlations between RFI and MMI scores and weak to moderate correlations with environmental variables, which varied in importance with each of 9 ecoregions. We conclude that the RFI is a useful indicator of a stream ecosystem service, which should be of greater interest to the U.S.A. public and traditional fishery management agencies than are MMIs, which tend to be more useful for ecologists, environmentalists and environmental quality agencies.

A population model provides support for management decisions, enables ongoing research and reinforces strong partnerships to manage a threatened freshwater crayfish

Abstract Many freshwater crayfish are threatened with extinction owing to varied threats such as urban development, pollution, over‐harvest, and climate change, as well as invasive species. A recently published manuscript in Aquatic Conservation: Marine and Freshwater Ecosystems described a stochastic, age‐based population model for the large freshwater crayfish Murray crayfish, Euastacus armatus, which is now threatened across much of its range in the Murray–Darling Basin in south‐eastern Australia. The model was constructed for three regional populations using the best available knowledge of life‐history traits such as longevity, size at onset of sexual maturity, fecundity, and survival, along with an account of density dependence. The model provides a framework to explore aspects of the conservation and management of the species, including assessing the influence of recreational harvest and environmental disturbance such as hypoxic blackwater, which affected the species significantly in 2010–2011. The application of the model provided retrospective justification for regulation amendments and highlighted biologically realistic timeframes for the recovery of impaired populations. This knowledge has assisted multi‐jurisdictional fisheries management agencies to undertake routine reviews of fishery regulations, as well as to inform stakeholders of the benefits of the regulation amendments. Refinement of the modelling framework has already provided additional insight and it is anticipated that future application will help to address other important management questions. The modelling outcomes are at present informing conservation assessment of the species under the Australian Government's Environmental Protection and Biodiversity Conservation Act 1999. The benefit of the population model can be summarized as: providing a framework to inform and justify management decisions; enabling additional research; and guiding conservation assessment. This has strengthened strong partnerships (between ecologists, managers, and recreational fishers) required to manage the species effectively.

The Effect of Raceway Grading on Return to Creel for Catchable‐Sized Hatchery Rainbow Trout

AbstractHatchery trout of catchable size (i.e., about 250 mm total length; hereafter termed “catchables”), which are stocked into put‐and‐take fisheries, are expensive to raise, so fisheries management agencies strive to modify rearing practices to maximize the proportion of stocked catchables that anglers catch. We graded fish in production‐level hatchery rearing units at both fingerling and catchable size, dividing the fish into “leaders” (herein, the larger fish in a rearing unit, separated during a grading event) and “laggers” (the smaller fish). We hypothesized that (1) grading and immediate stocking of catchable leaders and short‐term retention and continued feeding of catchable laggers might increase lagger growth and result in a larger average size of fish being stocked (relative to fish from ungraded raceways), potentially improving overall return to creel for the graded group and (2) grading and separation of fingerling leaders and laggers early in the rearing process may reduce competition between smaller and larger fish for the remainder of the rearing period, potentially improving overall poststocking return to creel for the entire group without the need for catchable grading at the time of stocking. We found that grading catchables just prior to stocking slightly increased the mean size at stocking (compared with ungraded control fish) for the first stocking period, which resulted in slightly higher return to creel for stocked fish. However, across the entire stocking period and with equal feed between groups, mean size at release was nearly identical between the graded and the control fish, as was return to creel by anglers. Grading fingerlings to separate leaders and laggers for the remainder of the rearing period also had no positive effect on angler catch. Our findings suggest that production‐level grading is ineffective at increasing the growth of laggers, so it will not increase overall size at stocking. Consequently, improvements in angler catch are unlikely to materialize from grading hatchery trout prior to stocking them into put‐and‐take fisheries.