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At least 577 records · Page 32Linked to original sources
USGS2018

State-level freshwater mussel programs: Current status and a research framework to aid in mussel management and conservation

Despite increased focus on their ecology and conservation, freshwater mussels remain one of the most imperiled groups of aquatic organisms. We documented current management actions, resources, and challenges in managing freshwater mussels in the United States through a survey of state natural resource agencies. Approximately 85% of surveyed states ( N = 40) actively managed mussel populations. Common challenges to mussel conservation included limited funding, lack of public awareness, and poor understanding of habitat needs and risks. We present a research framework, currently underway in Missouri, to support a regional mussel conservation assessment whereby habitat needs are identified, risks are assessed, and standardized protocols are developed to monitor and detect trends in mussel assemblages and threats. The research framework conforms to the National Strategy for the Conservation of Native Freshwater Mollusks and is adaptable to other states. With full consideration of resource limitations, we explore how this framework can improve the effectiveness of mussel conservation efforts.

Fisheries↗
USGS2019

Return of a giant: Coordinated conservation leads to the first wild reproduction of Lahontan Cutthroat Trout in the Truckee River in nearly a century

Many freshwater fish populations have been greatly reduced, with particular loss of migratory fishes. Recovering depleted populations is challenging as threats are often plentiful and complex, especially in arid environments where demands for water resources are high. Here, we describe how a collaborative, multifaceted approach has spurred natural reproduction—a major step towards Lahontan Cutthroat Trout Oncorhynchus clarkii henshawi (LCT) recovery in Pyramid Lake and the Truckee River, Nevada, once home to one of largest freshwater salmonids in North America. The factors limiting LCT were immense, including habitat fragmentation, degradation, and non‐native species attributes common in the declines of native salmonids. Yet for the first time in over 80 years and each year since 2014, adfluvial LCT have spawned in the lower Truckee River, resulting in the production of tens of thousands of young‐of‐year. The progress and positive trajectory towards recovery were driven by a holistic view of the Truckee River watershed beginning in the early 1990's that envisioned bringing numerous conservation building blocks together to expedite the conservation and recovery for the listed fishes of Pyramid Lake. Although additional challenges remain, the LCT recovery program in the Truckee River basin provides a template for the conservation of imperiled fishes.

Nevada↗
USGS2020

InFish: A professional network to promote global conservation and responsible use of inland fish

Inland fishes and fisheries make substantial contributions to individuals, society, and the environment in a changing global landscape that includes climate, water allocations, and societal changes. However, current limitations to valuing the services provided by inland fish and their fisheries often leaves them out of key decision‐making discussions. InFish is a voluntary professional network with over 120 members from over 50 organizations in over 20 countries that seeks to address challenges facing inland fish through novel approaches and international collaborations. InFish fosters opportunities to share knowledge, pursue proposals, publications, and conference‐related events focused on inland fisheries. InFish has become a source of inland fisheries expertise, working collectively towards global conservation and sustainable use of inland fish through informing scientifically sound management practices. As such, InFish may serve as a model network for other natural resource challenges now and into the future.

Fisheries Magazine↗
USGS2022

Toward improved prediction of streamflow effects on freshwater fishes

Understanding the effects of hydrology on fish populations is essential to managing for native fish conservation. However, despite decades of research illustrating streamflow influences on fish habitat, reproduction and survival, biologists remain challenged when tasked with predicting how fish populations will respond to changes in flow regimes. This uncertainty stems from insufficient understanding of the context-dependent mechanisms underlying fish responses to, for example, periods of reduced flow or altered frequency of high-flow events. We aim to address this gap by drawing on previous research to hypothesize mechanisms by which low- and high-flows influence fish populations and communities, identifying challenges that stem from data limitations and ecological complexity, and outlining research directions that can advance an empirical basis for prediction. Focusing flow-ecology research on testing and refining mechanistic hypotheses can help narrow management uncertainties and better support species conservation in changing flow regimes.

Fisheries Magazine↗
USGS2023

Environmental DNA as a tool for better understanding the distribution, abundance, and health of Atlantic and Pacific salmon

The development and application of approaches to detect and quantify environmental DNA (eDNA) have potential to improve our understanding of the distribution, abundance, and health of Atlantic Salmon Salmo salar and Pacific salmon Oncorhynchus spp. Here, we review 61 articles focusing on eDNA applications pertaining to salmon occupying natural habitat and aquaculture facilities in the context of advances, opportunities, and challenges. Given recent advances, eDNA now serves as a useful tool for detecting Atlantic Salmon and Pacific salmon and understanding threats to the health of fish and their habitats. Opportunities exist to apply sensitive and minimally invasive eDNA approaches to detect fish and assess fish habitat, assess range expansions of salmon and salmon pathogens, and detect invasive species that may threaten salmon health and abundance. Near real-time eDNA detection and quantification approaches to inform fisheries management may be on the horizon. Challenges limiting the widespread application of eDNA approaches for informing salmon management include accounting for the many factors affecting detection and quantification of eDNA, limits of data for deriving inference, and expense. Through continued development and refinement, eDNA approaches are anticipated to become increasingly available to, and utilized by, managers of Atlantic Salmon and Pacific salmon fisheries.

Fisheries Magazine↗
USGS2016

Current limitations and recommendations to improve testing for the environmental assessment of endocrine active substances

In the present study, existing regulatory frameworks and test systems for assessing potential endocrine active chemicals are described, and associated challenges are discussed, along with proposed approaches to address these challenges. Regulatory frameworks vary somewhat across geographies, but all basically evaluate whether a chemical possesses endocrine activity and whether this activity can result in adverse outcomes either to humans or to the environment. Current test systems include in silico, in vitro, and in vivo techniques focused on detecting potential endocrine activity, and in vivo tests that collect apical data to detect possible adverse effects. These test systems are currently designed to robustly assess endocrine activity and/or adverse effects in the estrogen, androgen, and thyroid hormone signaling pathways; however, there are some limitations of current test systems for evaluating endocrine hazard and risk. These limitations include a lack of certainty regarding: 1) adequately sensitive species and life stages; 2) mechanistic endpoints that are diagnostic for endocrine pathways of concern; and 3) the linkage between mechanistic responses and apical, adverse outcomes. Furthermore, some existing test methods are resource intensive with regard to time, cost, and use of animals. However, based on recent experiences, there are opportunities to improve approaches to and guidance for existing test methods and to reduce uncertainty. For example, in vitro high-throughput screening could be used to prioritize chemicals for testing and provide insights as to the most appropriate assays for characterizing hazard and risk. Other recommendations include adding endpoints for elucidating connections between mechanistic effects and adverse outcomes, identifying potentially sensitive taxa for which test methods currently do not exist, and addressing key endocrine pathways of possible concern in addition to those associated with estrogen, androgen, and thyroid signaling.

Integrated Environmental Assessment and Management↗
USGS2024

The LTAR Grazing Land Common Experiment at the Jornada Experimental Range: Old genetics, new precision technologies, and adaptive value chains

Rangelands and the supply chains connected to them are central to the agrifood systems of the Southwestern United States. Local ranchers are simultaneously arid lands managers, herd managers, and marketing managers. To stay in business, they must constantly adapt to unpredictable forage resources and markets while conserving soils and vegetation resources for the long term. As climate warming and drying exacerbate the complexity and difficulty of day-to-day production, producers and policy-makers are seeking alternatives to “business as usual”. To meet this need, the LTAR-Jornada team has developed a package of strategies to help producers adapt to the local and inter-regional challenges. The package includes heritage cattle, precision ranching systems, and adaptive value chains. Five ranches across the Southwest have adopted different combinations of the strategies and are partnering to measure their benefits and drawbacks in real-world conditions. Opportunities for controlled experimentation differ among the ranches, so we use LTAR’s indicator system to assess and compare results. Even as we invest in co-producing knowledge about these three strategies, we recognize that progressive aridification and urbanization of Southwestern rangelands create challenges for which a single “silver bullet” agricultural innovation is unlikely to provide durable solutions. We are learning from our customers and stakeholders about ways to adjust the development of new options.

New Mexico↗
USGS2014

Beta-thymosin gene polymorphism associated with freshwater invasiveness of alewife ( Alosa pseudoharengus )

Predicting the success of a species’ colonization into a novel environment is routinely considered to be predicated on niche-space similarity and vacancy, as well as propagule pressure. The role genomic variation plays in colonization success (and the interaction with environment) may be suggested, but has not rigorously been documented. To test an hypothesis that previously observed ecotype-specific polymorphisms between anadromous and landlocked alewife (Alosa pseudoharengus) populations are an adaptive response to osmoregulatory challenges rather than a result of allele sampling at founding, we examined multiple anadromous and landlocked (colonized) populations for their allelic profiles at a conserved region (3’-UTR end) of a β-thymosin gene whose protein product plays a central role in the organization of cytoskeleton. The putatively ancestral β-thymosin allele was prevalent in anadromous populations, whereas a newly derived allele was overrepresented in landlocked populations; a third allele was exclusive to the anadromous populations. We also conducted a complementary set of salinity exposure experiments to test osmoregulatory performance of the alewife ecotypes in contrasting saline environments. The pattern of variation and results from these challenges indicate a strong association of β-thymosin with colonization success and a transition for species with an anadromous life-history to one with only a freshwater component.

Journal of Experimental Zoology↗
USGS2017

Implementing the 2012 North American Waterfowl Management Plan revision: Populations, habitat, and people

The North American Waterfowl Management Plan (NAWMP) has established a model for wildlife conservation planning over the last 3 decades. Management at a continental scale, leveraged funding, regional partnerships, and a strong science basis have been notable features. Periodic updates to the NAWMP occurred since implementation in 1986; however, a fundamental revision was accomplished in 2012 after extensive stakeholder engagement. An explicit fundamental goal for waterfowl conservation supporters was added in 2012, complementing existing goals for sustainable populations and sufficient habitat found in previous updates. We present a synopsis of progress toward implementation of the 2012 NAWMP and challenge the waterfowl management community to continue with meaningful steps toward achieving NAWMP goals. Adding goals and objectives for supporters increases potential relevance of NAWMP; however, it also presents a level of complexity that was not entirely anticipated. Additionally, the 2012 NAWMP recognized that traditional support from waterfowl hunters alone will not be sufficient to support waterfowl conservation in the future. Simultaneous consideration of multiple objectives, although implicit before, now is a specific focus for habitat and harvest management affecting hunters and other users of the waterfowl resource. The waterfowl management community is faced with revisiting objectives and management actions related to harvest regulations, landscape priorities, habitat conservation, and public engagement to garner broader support. These persistent management challenges are tangible and relevant candidates for greater integration. Ultimately, the structures and processes supporting waterfowl management also will need to be reconsidered.

Journal of Wildlife Management↗
USGS2019

A collaborative approach to bridging the gap between wildlife managers and researchers

Although most wildlife professionals agree that science should inform wildlife management decisions, disconnect still exists between researchers and managers. If researchers are not striving to incorporate their findings into management decisions, support for research programs by managers can wane. If managers are not using research findings to inform management decisions, those decisions may be less effective or more vulnerable to legal challenges. Both of these situations can have negative consequences for wildlife conservation. We outline a collaborative research‐management approach to bridging the gap between wildlife managers and researchers. We describe differences in perspectives, perceptions, and priorities between managers and researchers; outline how and why the divide between researchers and managers has likely occurred and continues to grow; and present specific strategies and recommendations to foster stronger collaborations between managers and researchers. We advocate increased synergy between managers and researchers based on a shared vision of conservation and a collaborative structure that rewards researchers and managers. Most importantly, we suggest that relationships and communication between managers and researchers must be established early in research development and decision‐making processes, fostering the trust needed for collaboration. Institutions and agencies can facilitate these relationships by creating opportunities and incentives for integrating collaborative research into management decisions. We suggest this approach will strengthen ties between researchers and managers, increase relevance of research to management decisions, promote effectiveness of management decisions, reduce legal challenges, and ultimately produce positive, tangible, and lasting effects on wildlife conservation.

Journal of Wildlife Management↗
USGS2012

A matter of tradeoffs: reintroduction as a multiple objective decision

Decision making in guidance of reintroduction efforts is made challenging by the substantial scientific uncertainty typically involved. However, a less recognized challenge is that the management objectives are often numerous and complex. Decision makers managing reintroduction efforts are often concerned with more than just how to maximize the probability of reintroduction success from a population perspective. Decision makers are also weighing other concerns such as budget limitations, public support and/or opposition, impacts on the ecosystem, and the need to consider not just a single reintroduction effort, but conservation of the entire species. Multiple objective decision analysis is a powerful tool for formal analysis of such complex decisions. We demonstrate the use of multiple objective decision analysis in the case of the Florida non-migratory whooping crane reintroduction effort. In this case, the State of Florida was considering whether to resume releases of captive-reared crane chicks into the non-migratory whooping crane population in that state. Management objectives under consideration included maximizing the probability of successful population establishment, minimizing costs, maximizing public relations benefits, maximizing the number of birds available for alternative reintroduction efforts, and maximizing learning about the demographic patterns of reintroduced whooping cranes. The State of Florida engaged in a collaborative process with their management partners, first, to evaluate and characterize important uncertainties about system behavior, and next, to formally evaluate the tradeoffs between objectives using the Simple Multi-Attribute Rating Technique (SMART). The recommendation resulting from this process, to continue releases of cranes at a moderate intensity, was adopted by the State of Florida in late 2008. Although continued releases did not receive support from the International Whooping Crane Recovery Team, this approach does provide a template for the formal, transparent consideration of multiple, potentially competing, objectives in reintroduction decision making.

Journal of Wildlife Management↗
USGS2026

Whatever it takes— Shaping the L&O Letters Early Career Publication Honor to deliver true benefit

There are clear advantages for those who openly share their research. Publishing Open Access (OA) articles can increase author visibility (McCabe and Snyder 2014 ), improve productivity metrics (i.e., more diverse and higher citation rates; Huang et al. 2024 ; Piwowar et al. 2018 ), widen collaborative networks (Tai and Robinson 2018 ), and help secure future funding and/or comply with funder mandates (Herrmannova et al. 2019 ; Larivière and Sugimoto 2018 ; McKiernan et al. 2016 and references therein). These benefits can be vital for students and early career researchers (ECRs) trying to advance and thrive in academia. However, publishing papers in Gold OA journals such as L&O Letters comes at a notable financial cost, as these journals require that the corresponding author (or their organization or funder) pay a fee to make their published article immediately freely available to the public. These article processing charges can be prohibitively expensive (Fontúrbel and Vizentin-Bugoni 2021 ; Mekonnen et al. 2022 ; Ross-Hellauer et al. 2022 ). While Read and Publish agreements and waiver programs may be available to help cover these costs, these programs often exclude independent authors as well as those affiliated with ineligible or non-participating institutions (e.g., publisher waivers using the Research4Life eligibility criteria for access currently only allow authors from one of 13 South American countries/territories to publish free of charge). Besides the financial barrier, authors from underrepresented groups can also face a myriad of other publishing roadblocks, such as linguistic challenges (for speakers of English as a foreign language; Amano et al. 2023 ; Franco-Santos 2024 ; Ramírez-Castañeda 2020 ) and geopolitical-scientific bias (e.g., science conducted in the Global South being seen as less impactful and innovative than that conducted in the Global North; Ghosh 2022 ; Smits et al. 2025 ). For context, Global South (GS) and Global North (GN) are not geographic determinations (i.e., South and North hemispheres), but geopolitical classifications regarding a nation's level of development (underdeveloped, developing, or developed). For example: Australia and Brazil are both located in the southern hemisphere, but the former is considered as a Global North (developed) country and the latter as a Global South (underdeveloped or developing) country. When a subset of researchers is unable to openly publish their work, the diversity of voices represented in OA literature can decline (Williams et al. 2023 ). Loss of diversity is a loss to science, as diversity increases productivity, innovation, and scientific impact (refer to opening quote; Freeman and Huang 2014 ; AlShebli et al. 2018 ; Tomillo et al. 2022 ). To partially address the above-mentioned challenges and enable underfunded ECRs to publish their work in OA format, the biennial L&O Letters Early Career Publication Honor (ECPH) was established in 2020 by the ASLO Raelyn Cole Editorial (RCE) Fellows (Hotaling et al. 2022 ). Below we reflect on the benefits, outcomes, and scientific impact of the 2022 call and introduce the articles it helped publish in L&O Letters , which are bundled in this section of the ECPH Virtual Issue. Articles published in L&O Letters during other calls are available in their respective sections. We also refer the reader to six articles published by ECRs in other journals (not included in this Virtual Issue) whose content originally warranted their leading author an ECPH in 2022.

Limnology and Oceanography Letters↗
USGS2019

Characterizing angler preferences for Largemouth Bass, Bluegill, and Walleye fisheries in Wisconsin

Managing recreational fisheries in lake-rich landscapes with diverse fish communities and anglers alike presents a social and biological challenge for managers. Understanding angler preferences is central to navigating these challenges and can aid in predicting shifts in angler behavior in response to management actions or changing fish populations. Species-specific angler surveys do not incorporate tradeoffs inherent in multispecies fisheries, thus limiting their application to real-world management issues. To better understand angler preferences in relation to realistic tradeoffs among different fishing opportunities, we conducted a survey of Wisconsin anglers in 2013–2014 that included questions requiring anglers to choose between fisheries providing different outcomes. We used stated-preference modeling to quantify angler preferences associated with Bluegill Lepomis macrochirus , Largemouth Bass Micropterus salmoides , and Walleye Sander vitreus fisheries. Next, we conducted a latent class analysis using survey responses to classify anglers into subgroups. Finally, we assessed the sensitivity of angler choice to changes in fishing opportunities. Results of the stated-preference models indicated that both residents and nonresidents largely prefer “quality” (i.e., moderate catch rate and size structure) over “action” or “trophy” Bluegill fisheries and that characteristics of Largemouth Bass fisheries have more value to nonresidents than to residents. Aspects of the Bluegill fishery were most important in choosing among hypothetical lakes for resident respondents. Five angler subgroups were identified that show the importance of Bluegill and Walleye but shed additional light on anglers’ commitment level and nonresidents’ preference for Largemouth Bass. In addition, simulations of changes in Walleye, Largemouth Bass, and Bluegill fisheries indicated that maintenance of quality Bluegill fisheries is important to ensuring continued angler participation, while the retention of high-yield Walleye fisheries is likely paramount to a subgroup of anglers. Our results offer insight into angler preferences across the lake-rich landscape of Wisconsin and demonstrate how angler behavior may shift in response to transitions in fishing opportunities.

Wisconsin↗
USGS2019

An importance–satisfaction analysis of trout license holders in Georgia

As anglers become increasingly diverse, fisheries managers are challenged to find ways to satisfy users with divergent preferences while conserving a limited resource on a limited budget. With this management challenge in mind, this study combines previous angler specialization research with an importance–satisfaction analysis (ISA) to aid fisheries managers in better understanding users with divergent preferences. An ISA involves asking stakeholders to simultaneously evaluate the importance of salient attributes of their fishing experience and their satisfaction with those attributes, which allows for graphical depiction of each attribute in one of four quadrants with managerial implications: Concentrate Here, Keep up the Good Work, Possible Overkill, and Low Priority. The data were collected via a mail-administered survey that was sent to 4,000 licensed trout anglers who were residents of Georgia. The anglers were asked to evaluate 10 catch and 7 noncatch attributes as well as answer questions that were used to measure levels of angler specialization. A K -means cluster analysis was used to segment the 469 respondents into three groups based on their specialization level. Analysis of variance (ANOVA) was used to determine whether anglers’ preferences differed by level of specialization. The results revealed that specialization groups differed in the level of importance that they placed on 6 catch and 4 noncatch attributes and in their levels of satisfaction with 5 catch and 2 noncatch attributes. There were also differences among the groups in quadrant placement for both catch and noncatch attributes. The respondents agreed that habitat improvement initiatives, adding new fishable water, and clear signage of regulations were of relatively high importance, with habitat improvement initiatives as the only attribute to fall in the Concentrate Here quadrant for all three clusters. The average responses for importance and satisfaction were highest for the most specialized group and lowest for the least specialized group. Combining segmenting techniques, like cluster analysis with ISA, offers fisheries managers the opportunity to gauge different user groups’ perceptions of salient fishery attributes.

Georgia↗
USGS2022

Special section overview: Effects of ecosystem change on North American percid populations.

Walleye Sander vitreus , Sauger S. canadensis , and Yellow Perch Perca flavescens (referred to as percids herein) are collectively among the most culturally and ecologically important fish species in North America. As ecosystems change in response to environmental drivers, such as climate change, nutrient loading, and invasive species, there is a need to understand how percid populations respond to these changes. To address this need, a symposium was held during the 81st Annual Midwest Fish and Wildlife Conference to bring fishery scientists and managers together to describe and discuss percid population responses to ecosystem change. Prevailing symposium themes included the challenge of identifying mechanisms responsible for population-level changes, developing strategies to adaptively manage for resilient fisheries, and consideration of scale, context, and methods when interpreting variable results. Given the uncertainty of how ecosystem changes affect percid populations, participants emphasized the importance of communicating uncertainties to stakeholders, implementing data-driven management strategies, setting realistic goals, and revising management actions in an adaptive framework. There was universal agreement on both the challenge and necessity of facilitating constructive engagement among stakeholders in cooperative decision making. Symposium participants identified knowledge gaps and discussed future efforts to build on our current understanding of percid populations, including continuation of long-term monitoring, improved standardization of evaluation metrics, implementing adaptive management experiments to identify causal relationships, development of more robust analytical methods, use of historical data sources, and refining techniques to realistically convey management options to stakeholders.

North American Journal of Fisheries Management↗
USGS2011

Investigation of preparation techniques for δ2H analysis of keratin materials and a proposed analytical protocol

Accurate hydrogen isotopic measurements of keratin materials have been a challenge due to exchangeable hydrogen in the sample matrix and the paucity of appropriate isotopic reference materials for calibration. We found that the most reproducible δ 2 H VSMOW‐SLAP and mole fraction of exchangeable hydrogen, x (H) ex , of keratin materials were measured with equilibration at ambient temperature using two desiccators and two different equilibration waters with two sets of the keratin materials for 6 days. Following equilibration, drying the keratin materials in a vacuum oven for 4 days at 60 °C was most critical. The δ 2 H analysis protocol also includes interspersing isotopic reference waters in silver tubes among samples in the carousel of a thermal conversion elemental analyzer (TC/EA) reduction unit. Using this analytical protocol, δ 2 H VSMOW‐SLAP values of the non‐exchangeable fractions of USGS42 and USGS43 human‐hair isotopic reference materials were determined to be –78.5 ± 2.3 ‰ and –50.3 ± 2.8 ‰, respectively. The measured x (H) ex values of keratin materials analyzed with steam equilibration and N 2 drying were substantially higher than those previously published, and dry N 2 purging was unable to remove absorbed moisture completely, even with overnight purging. The δ 2 H values of keratin materials measured with steam equilibration were about 10 ‰ lower than values determined with equilibration in desiccators at ambient temperatures when on‐line evacuation was used to dry samples. With steam equilibrations the x (H) ex of commercial keratin powder was as high as 28 %. Using human‐hair isotopic reference materials to calibrate other keratin materials, such as hoof or horn, can introduce bias in δ 2 H measurements because the amount of absorbed water and the x (H) ex values may differ from those of unknown samples. Correct δ 2 H VSMOW‐SLAP values of the non‐exchangeable fractions of unknown human‐hair samples can be determined with atmospheric moisture equilibration by normalizing with USGS42 and USGS43 human‐hair reference materials when all materials have the same powder size.

Rapid Communications in Mass Spectrometry↗
USGS2011

Effects of dams in river networks on fish assemblages in non-impoundment sections of rivers in Michigan and Wisconsin, USA

Regional assessment of cumulative impacts of dams on riverine fish assemblages provides resource managers essential information for dam operation, potential dam removal, river health assessment and overall ecosystem management. Such an assessment is challenging because characteristics of fish assemblages are not only affected by dams, but also influenced by natural variation and human-induced modification (in addition to dams) in thermal and flow regimes, physicochemical habitats and biological assemblages. This study evaluated the impacts of dams on river fish assemblages in the non-impoundment sections of rivers in the states of Michigan and Wisconsin using multiple fish assemblage indicators and multiple approaches to distinguish the influences of dams from those of other natural and human-induced factors. We found that environmental factors that influence fish assemblages in addition to dams should be incorporated when evaluating regional effects of dams on fish assemblages. Without considering such co-influential factors, the evaluation is inadequate and potentially misleading. The role of dams alone in determining fish assemblages at a regional spatial scale is relatively small (explained less than 20% of variance) compared with the other environmental factors, such as river size, flow and thermal regimes and land uses jointly. However, our results do demonstrate that downstream and upstream dams can substantially modify fish assemblages in the non-impoundment sections of rivers. After excluding river size and land-use influences, our results clearly demonstrate that dams have significant impacts on fish biotic-integrity and habitat-and-social-preference indicators. The influences of the upstream dams, downstream dams, distance to dams, and dam density differ among the fish indicators, which have different implications for maintaining river biotic integrity, protecting biodiversity and managing fisheries.

Wisconsin and Michigan↗
USGS2024

Upstream experience and experimental translocation of invasive bigheaded carps results in increased upstream passage success at a navigation lock in a large river

Fish movements in regulated rivers can be challenging to study because anthropogenic modifications, such as locks and dams, can influence animal behavior. Upper Mississippi River Lock and Dam 19 (LD 19), for example, is an invasive carp movement bottleneck due to an impassable dam. Upstream fish passage at LD19 is restricted to the lock chamber, making it an optimal location to test invasive fish deterrents that could limit further range expansion. Evaluating the effectiveness of experimental deterrents requires baseline knowledge of fish movements and suitable sample sizes of fish encountering the deterrents to ensure adequate statistical power. Some evidence indicates fish with prior upstream experience may return upstream or challenge potential deterrents at a higher rate than fish without such experience. To test how previous upstream experience could increase the rate at which fish moved upstream through a navigation lock chamber, we compared upstream passage through LD 19 using bigheaded carp captured below the dam (downstream-origin) and two groups of bigheaded carp captured upstream from the dam: those that swam downstream on their own volition (upstream-origin fish) and those that were captured upstream and translocated downstream of LD 19 (translocated upstream-origin). Translocated upstream-origin carp demonstrated the highest rate of upstream passage, with 59% of the fish detected downstream from LD 19 passing upstream during our study. In contrast, downstream-origin carp made no upstream passages over 2 years. Fish origin was shown to influence upstream passage success. This may be an important consideration for fish passage studies and deterrent evaluations.

Illinois, Iowa↗