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At least 37 records · Page 2Linked to original sources
USGS2021

What can commercial fishery data in the Great Lakes reveal about juvenile sea lamprey (Petromyzon marinus) ecology and management?

The Laurentian Great Lakes of North America support a large and profitable freshwater fishery, but one continuously beset by parasitism from the invasive sea lamprey ( Petromyzon marinus ). Despite being the life stage that inflicts damage to the fishery, therefore necessitating a bi-national control program, our knowledge of juvenile sea lamprey ecology is poor and their response to control efforts are not assessed. Incidental capture of juvenile sea lamprey by commercial fishers is one means to collect data on this enigmatic life stage, and in Lake Huron such data have been collated since 1967. Here, we explore incidental captures of juvenile sea lamprey and their hosts from northern Lake Huron between 1987 and 2017 ( n = 33,246 observations) to address four objectives. Firstly, we document collection efforts by fishers to provide historical context to the dataset. Secondly, we pose and test a series of questions related to fishery encounter, host selection, growth, distribution, and sex ratio to highlight how these types of data can be informative regarding juvenile sea lamprey ecology. Results presented here could be used to develop biological hypotheses to be addressed in future work. Thirdly, we directly assessed whether juvenile sea lamprey capture data could be useful in corroborating trends observed in adult sea lamprey abundance and wounding, as well as in identifying abundance and wounding hotspots. Lastly, we summarize research and outreach efforts that have benefited from the capture of juvenile sea lamprey in recent years.

Great Lakes↗
USGS2023

Characterization of fish assemblages in eleven multi-use reservoirs from North Carolina, USA

Managing impounded river systems is a recurring challenge for aquatic resource professionals because reservoirs serve multiple functions with different ecological and socioeconomic outcomes. However, research on fishes in reservoirs has disproportionally focused on recreationally and economically important species, with less attention directed toward fish assemblages despite the potential for management at the assemblage level. As such, evaluation of relationships between reservoir fish assemblages and biotic and abiotic factors and testing whether assemblage structure is affected by changing environmental conditions may deepen ecological understanding and provide insights for reservoir fisheries management. Our overall objective was to assess these relationships in 11 reservoirs from North Carolina, USA. We sampled fish assemblages in the reservoirs, which spanned five river basins representing a range of habitat conditions, using experimental gillnets and pulsed DC nighttime electrofishing. Multivariate statistical analyses indicated that taxonomic differences in fish assemblage composition among river basins followed a gradient of productivity. The top contributing species to reservoir dissimilarity were bluegill ( Lepomis macrochirus ), gizzard shad ( Dorosoma cepedianum ), black crappie ( Pomoxis nigromaculatus ), and white perch ( Morone americana ). These four species were positively associated with factors that reflect increasing eutrophic conditions in the 11 reservoirs and could, therefore, serve as indicators of reservoir productivity, anthropogenic influence, and fish assemblage structure, in addition to their key role in reservoir fisheries management. Whereas ­fisheries research has historically focused on assessing fish ­populations, our results illustrate the ecological and management insights derived from simultaneously collecting assemblage- and population-level data. Research on reservoir fish assemblages in relation to biotic and abiotic conditions may help advance fish ecology and management alike.

North Carolina↗
USGS2025

Complexity and integration of recreational fisheries

Recreational fisheries are interconnected, complex, adaptive systems characterized by multiple direct and indirect interactions among ecological and human subsystems. This is important for many reasons, including that feedbacks between the social and ecological dimensions lead to difficult-to-predict, often entirely unexpected, outcomes and because many management and governance systems have multiple objectives that can involve social (e.g. fisher satisfaction), economic (e.g. license revenue), and ecological (e.g. fish conservation) dimensions. Embracing a social-ecological-system perspective can usher in an improved era of recreational fisheries science and management. Interdisciplinary approaches that unite experts across disciplines (e.g. social and ecological sciences) to create a unique theoretical, conceptual, and methodological identity are needed to gather crucial information from recreational fishers, quantify and predict fisher behaviours and outcomes from these behaviours, and integrate these findings into fisheries management. In this chapter, we lay the conceptual foundation for recreational fisheries as coupled social-ecological systems that are also complex and adaptive, and discuss the interdisciplinary approach to operationalize this book’s vision.

Book chapter↗
USGS2025

Adaptive management for recreational fisheries decisions in the face of uncertainty

Recreational fisheries management requires making decisions that consider social, economic, and ecological dimensions. The feedbacks among ecological changes and social responses by fishers create complexity and uncertainty. However, uncertainty can impede the integration of ecological and social dimensions, particularly when considering human behavioural responses to management decisions and ecological changes. One of the few ways to reduce these uncertainties is via experimentation at the system level. Adaptive management (and the larger umbrella of decision analysis) provides a framework to implement purposeful management experiments in a structured manner to learn through an iterative decision process, thereby allowing for the reduction in social and ecological uncertainties in response to planned policy interventions. We discuss the theory of adaptive management and conditions for which it is appropriate, as well as the benefits and costs of applying active versus passive adaptive management to reduce social and ecological uncertainties for recreational fisheries. We then provide key examples from previous studies on decisions for zoning in the Great Barrier Reef, Australia, stocking decisions that include stakeholder learning in Germany, and decisions for stocking and harvest management in British Columbia, that demonstrate best practices for implementation of adaptive management to reduce uncertainties surrounding human behaviour and other social and ecological objectives related to recreational fisheries.

Book chapter↗
USGS2025

Infection by the marine cestode Hepatoxylon trichiuri in returning Chinook salmon (Oncorhynchus tshawytscha) spawners in Patagonia: Implications for a novel fishery

Parasitological information may be useful for managing economically important fisheries by providing insights into population dynamics and health effects. The Chinook salmon ( Oncorhynchus tshawytscha ), an invasive species with high socio-ecological importance in South America, supports recreational and incipient artisanal fisheries. In Southern Chile, the recent approval of coastal fisheries for returning Chinook salmon in some regions highlights the importance of understanding salmon foraging, habitat use, and commercial value. However, such information is lacking. Parasites have been extensively used as cost-effective biological tags to identify fish stocks. We conducted the first parasitological examination of the marine tapeworm Hepatoxylon trichiuri larvae in returning adult Chinook salmon from the Cisnes River to assess its potential as a biological tag for returning Chinook salmon in Patagonia. Of 61 Chinook salmon from the Cisnes River, 52.46% were infected by H. trichiuri , with 1.65 ± 1.26 parasites per infected salmon (mean ± SD). Infection prevalence and intensity did not differ significantly between males and females. Infection intensity was higher in larger salmon but decreased with increasing salmon condition. Infection intensity was not significantly related to length, mass, or body condition. Infection prevalence and intensity of H. trichiuri varied spatially among Patagonian river-basin populations of Chinook salmon, thereby supporting the use of H. trichiuri as a biological tag. Our findings provide important parasitological metrics that may enhance future management practices by informing geographic variability in foraging locations of adult salmon and their commercial value for human consumption.

Cisnes River, Patagonia↗
USGS2023

Evaluating population trends of juvenile Atlantic Sturgeon at low abundance in a dynamic estuarine environment (Hudson River, New York)

Evaluating population trends in dynamic estuarine environments can be challenging, especially when survey data include a high percentage of zero observations. In fishery-independent surveys, zeros that come from reduced susceptibility to sample gears and reduced availability of the population to the survey impact survey catchability and negatively bias relative abundance indices. A zero-inflated negative binomial model was used to standardize a juvenile Atlantic Sturgeon ( Acipenser oxyrinchus oxyrinchus ) relative abundance index (Hudson River, New York) that included a high proportion (42%) of zero observations and intra- and interannually variable covariates. Reduced susceptibility was related to low water temperature, with the percentage of zeroes increasing rapidly below 7°C. Availability was influenced by temperature and distance to salt front, as catch rates increased with temperature and peaked in mesohaline waters ~27 km downstream of the predicted salt front. An alternative index suggested significant population growth ( r = 0.15; p -value = 0.007) occurred from 2004 to 2015. The zero-inflated model helped better understand Hudson River juvenile Atlantic Sturgeon ecology and relative trends in abundance, to better inform future management and monitoring decisions along the Atlantic Coast.

New York↗
USGS2025

Healing ogaa (walleye Sander vitreus) waters: Lessons and future directions for inland fisheries rehabilitation

ulturally, economically, and nutritionally valuable inland fisheries face many new challenges on top of chronic disturbances. In the upper midwestern United States, declines in cool- and coldwater fisheries have been observed, including ogaa/walleye Sander vitreus . In response to population declines, agencies have implemented rehabilitation efforts, and the frequency and intensity of efforts have increased recently given declines. Evaluating intervention outcomes is critical for institutional learning and to understand strategy effectiveness, but is difficult to do when multiple interventions are applied concurrently and in the absence of replication or controls. This review documents walleye rehabilitation efforts in the upper Midwest U.S., where a rehabilitation effort was defined as a coordinated effort with the stated intention to restore a self-sustaining population such that it required limited-to-no further intervention. We discuss: (1) strategies used; (2) similarities and differences in metrics of success; (3) factors leading to success; and (4) recommendations that may increase future successful rehabilitation. Strategies included harvest regulation changes, stocking, fish community manipulations, habitat enhancement, and partner discussions. Overall, evaluations of environmental, habitat, and fish community factors causing walleye population declines were not included in most rehabilitation plans before implementation. This review highlights an increased need for ecosystem-based fisheries management principles and cultivating ecological conditions that favor walleye as a potential path for future rehabilitation plans. Lessons drawn from rehabilitation plans are applicable to global inland fisheries to inform the conservation of declining fish populations.

Michigan, Minnesota, Wisconsin↗
USGS2023

Estimating lentic recreational fisheries catch and effort across the United States

Recreational fisheries represent a socially, ecologically, and economically significant component of global fisheries. The U.S. Inland Creel and Angler Survey Catalog (CreelCat) database includes inland recreational fisheries survey data across the United States to facilitate large-scale analyses. However, because survey methods differ, a statistical method capable of integrating these surveys is necessary to assess patterns and relationships across regions. Here, we developed a hierarchical generalized linear mixed modeling approach to estimate the relationship between daily recreational fisheries catch and effort based on waterbody, socio-economic, and ecological covariates. We applied this approach to CreelCat data on lentic waterbodies and found that recreational fisheries catch and effort were non-linearly related (i.e., catch per unit of effort declined as effort increased), where effort varied regionally and by waterbody area, median county age, and distance to nearest primary road. This modeling approach could be used to inform data-poor regions or waterbodies, make comparisons across spatial scales, and, with the inclusion of socio-economic and ecological factors, inform management techniques in an era of shifting demographics and landscapes.

Fisheries Management and Ecology↗
USGS2022

Resist, accept, and direct responses to biological invasions: A social–ecological perspective

Biological invasions represent an important and unique case of ecological transformation that can strongly influence species and entire ecosystems. Challenges in managing invasions arise on multiple fronts, ranging from diverse and often divergent values associated with native and introduced species, logistical constraints, and transformation via other change agents (e.g., climate and land-use change). We address biological invasions considering the Resist-Accept-Direct (RAD) framework for addressing ecological transformation. Because RAD is focused on decisions, we address both social and ecological factors that influence preferences for decision alternatives. We address social factors first as these can constrain the range of alternatives considered in an ecological context. Next, we address ecological dynamics by modeling trajectories from RAD alternatives in a two-species scenario involving impacts of introduced brook trout ( Salvelinus fontinalis ) on native bull trout ( S. confluentus ). Results reveal that decision alternatives aligned with each of the major components of RAD can produce positive outcomes. In a management context, these findings highlight the value of investing in early engagement to fully identify decision alternatives, formalizing models of system dynamics to understand ecological trajectories, and applying this knowledge to set the stage for longer term efforts to address biological invasions.

Fisheries Management and Ecology↗
USGS2011

Luring anglers to enhance fisheries

Current fisheries management is, unfortunately, reactive rather than proactive to changes in fishery characteristics. Furthermore, anglers do not act independently on waterbodies, and thus, fisheries are complex socio-ecological systems . Proactive management of these complex systems necessitates an approach—adaptive fisheries management—that allows learning to occur simultaneously with management. A promising area for implementation of adaptive fisheries management is the study of luring anglers to or from specific waterbodies to meet management goals. Purposeful manipulation of anglers, and its associated field of study, is nonexistent in past management. Evaluation of different management practices (i.e., hypotheses) through an iterative adaptive management process should include both a biological and sociological survey to address changes in fish populations and changes in angler satisfaction related to changes in management. We believe adaptive management is ideal for development and assessment of management strategies targeted at angler participation. Moreover these concepts and understandings should be applicable to other natural resource users such as hunters and hikers.

Journal of Environmental Management↗
USGS2019

The future of recreational fisheries: Advances in science, monitoring, management, and practice

Recreational fisheries (RF) are complex social-ecological systems that play an important role in aquatic environments while generating significant social and economic benefits around the world. The nature of RF is diverse and rapidly evolving, including the participants, their priorities and behaviors, and the related ecological impacts and social and economic benefits. RF can lead to negative ecological impacts, particularly through overexploitation of fish populations and spread of non-native species and genotypes through stocking. Hence, careful management and monitoring of RF is essential to sustain these ecologically and socioeconomically important resources. This special issue on recreational fisheries contains diverse research, syntheses, and perspectives that highlight the advances being made in RF research, monitoring, management, and practice, which we summarize here. Co-management actions are rising, often involving diverse interest groups including government and non-government organizations; applying collaborative management practices can help balance social and economic benefits with conservation targets. Technological and methodological advances are improving the ability to monitor biological, social, and economic dynamics of RF, which underpin the ability to maximize RF benefits through management actions. To ensure RF sustainability, much research focuses on the ecological aspects of RF, as well as the development of management and angling practices that reduce negative impacts on fish populations. For example, angler behavior can be influenced to conform to conservation-minded angling practices through regulations, but is often best accomplished through growing bottom-up social change movements. Anglers can also play an important role in fisheries monitoring and conservation, including providing data on fish abundance and assemblages (i.e., citizen science). The increasing impacts that growing human populations are having on the global environment are threatening many of the natural resources and ecosystem services they provide, including valuable RF. However, with careful development of research initiatives, monitoring and management, sustainable RF can generate positive outcomes for both society and natural ecosystems and help solve allocation conflicts with commercial fisheries and conservation.

Fisheries Research↗
USGS2019

The Laurentian Great Lakes: A case study in ecological disturbance and climate change

Climate change effects are already significant, but can also magnify other ecological problems. This can be clearly seen in the Laurentian Great Lakes, which have suffered habitat degradation, fishery overharvest and dramatic alterations by invasive species. Thermal changes are expected to cause extensive loss of suitable fish habitat, and changing precipitation patterns will aggravate the problems with our highly modified lotic and lentic systems. A brief summary of the historic ecological context provided by the Great Lakes case is presented, followed by the descriptions of selected tools that help to understand and evaluate both ecological and climate change problems. Species distribution models and habitat classification combined with climate change predictions can identify the distribution and extent of optimal habitats, and identify which are most vulnerable to climate change. Ecological flow modelling can help to identify when critical flow changes are likely. Mechanistic simulation modelling specifies understanding of how aquatic systems function and can reveal cause and effect relationships. These tools can be used to help managers to protect optimal habitat, resist climate change effects to other habitats and adapt cultural systems to climate‐altered aquatic systems.

Great Lakes↗
USGS2018

Ecology and conservation of the American eel in the Caribbean region

The majority of American eel, Anguilla rostrata LeSueur, knowledge is derived from temperate regions in the United States and Canada, with little known from its tropical Caribbean distribution. Findings of original research on American eel distribution, abundance, population biology, habitat ecology and threats from the Caribbean island of Puerto Rico were synthesised. American eel were captured from 48 of 116 sites (41.4%) in 26 of 49 river basins (53.1%) during 2005–2016, and it was extirpated upstream of dams and migration barriers >3.0 m high (38.9% of habitat). Mean density and biomass were 438.9 fish/ha and 23.44 kg/ha, respectively. Upstream habitats favoured larger individuals, and females were larger than males. The swim‐bladder parasite Anguillicoloides crassus Kuwahara, Niimi & Hagaki was not found in 120 eels examined. Realised threats include dams and other migratory barriers, habitat loss and alteration and pollution; exotic species and commercial fishing are impending threats; and the least understood is climate change.

Fisheries Management and Ecology↗
USGS2023

Morphological differences between wild and hatchery-reared Bloater (Coregonus hoyi) from Lake Michigan, USA

Coregonines (ciscoes and whitefishes) are economically, ecologically, and culturally important fishes that are distributed throughout the Northern Hemisphere. In the Laurentian Great Lakes, coregonines declined throughout the 19th and 20th centuries, and managers have prioritized their restoration. A key restoration tool is reintroduction via stocking. However, hatchery-reared coregonines can display different morphologies than wild fish, which could affect their fitness. Unfortunately, our understanding of these differences is limited because previous work did not adequately remove allometric effects in morphological analyses. We compared morphologies between wild and hatchery-reared Bloater ( Coregonus hoyi ) from the same stock using appropriate size corrections. Hatchery-reared fish had shorter heads, shorter dorsal fins, and shallower bodies than wild fish. Moreover, some characters differed across wild fish collections. Our results improve our understanding of how artificial rearing can impact coregonine morphology, and we recommend future studies on what causes these differences and whether they impact fitness.

Fisheries Management and Ecology↗
USGS2006

Relationships among condition indices, feeding and growth of walleye in Lake Erie

Condition indices are often used as surrogates of fish health, growth, and feeding and to compare ecological well-being among fish populations. In an effort to identify easily measured indices, growth and food consumption were compared with gonadal-somatic index, liver-somatic index (LSI), fat-somatic index and relative weight (Wr) for ages 1-3 walleye, Sander vitreus (Mitchill), in Lake Erie from 1986 to 1988. The LSI and Wr were significantly correlated with growth rate or food consumption, but correlations were too small to be considered biologically meaningful. Furthermore, no consistent relationships between condition indices and growth or consumption were found among combinations of fish age and season. None of the indices are considered reliable surrogates for more laborious estimates of growth and food consumption for Lake Erie walleye. Significant relationships between Wr and relative abundance of key prey species warrant further investigation. ?? 2006 Blackwell Publishing Ltd.

Fisheries Management and Ecology↗
USGS2015

Sampling techniques for burbot in a western non-wadeable river

Burbot, Lota lota (L.), populations are declining throughout much of their native distribution. Although numerous aspects of burbot ecology are well understood, less is known about effective sampling techniques for burbot in lotic systems. Occupancy models were used to estimate the probability of detection ( ) for three gears (6.4- and 19-mm bar mesh hoop nets, night electric fishing), within the context of various habitat characteristics. During the summer, night electric fishing had the highest estimated detection probability for both juvenile ( , 95% C.I.; 0.35, 0.26–0.46) and adult (0.30, 0.20–0.41) burbot. However, small-mesh hoop nets (6.4-mm bar mesh) had similar detection probabilities to night electric fishing for both juvenile (0.26, 0.17–0.36) and adult (0.27, 0.18–0.39) burbot during the summer. In autumn, a similar overlap between detection probabilities was observed for juvenile and adult burbot. Small-mesh hoop nets had the highest estimated probability of detection for both juvenile and adult burbot (0.46, 0.33–0.59), whereas night electric fishing had a detection probability of 0.39 (0.28–0.52) for juvenile and adult burbot. By using detection probabilities to compare gears, the most effective sampling technique can be identified, leading to increased species detections and more effective management of burbot.

Fisheries Management and Ecology↗
USGS2014

Thermal ecology of subadult and adult muskellunge in a thermally enriched reservoir

The movement of adult muskellunge , Esox masquinongy Mitchill, has been investigated in a variety of systems, but temperature selection by muskellunge has not been examined where well-oxygenated waters were available over a range of temperatures for much of the year. Thirty subadult and adult muskellunge tagged internally with temperature-sensing radio tags were tracked from March 2010 to March 2011 in a Tennessee reservoir. Mean tag temperatures were 18.9 °C in spring (March to May), 22.1 °C in summer (June to August), 16.5 °C in autumn and 9.8 °C in winter (December to February). When the greatest range in water temperatures was available (7.1–33.3 °C; May to early August 2010), their realised thermal niche (mean ± 1 SD) was 22.3 °C ± 1.8; the realised thermal niche was affected by fish size (smaller fish selected slightly warmer temperatures) but not sex. An electric generating steam plant discharging warm water resumed operation in January 2011, and most (86%) tagged fish occupied the plume where temperatures were ≈10 °C warmer than ambient water temperatures. No mortalities were observed 15 days later when plant operations ceased. Their affinity for the heated plume prompted concerns that muskellunge will be too easily exploited when the plant operates during winter.

Tennessee↗