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At least 1,531 records · Page 85Linked to original sources
USGS2013

PCB concentrations and activity of sea lamprey Petromyzon marinus vary by sex

We determined the polychlorinated biphenyl (PCB) concentrations of 40 male and 40 female adult sea lampreys Petromyzon marinus captured in the Cheboygan River, a tributary to Lake Huron, during May 2011. In addition, we performed a laboratory experiment using passive integrated transponder tags to determine whether male adult sea lampreys were more active than female adult sea lampreys. Sex had a significant effect on PCB concentration, and PCB concentration at a given level of sea lamprey condition was approximately 25 % greater in males than in females. Adjusting for the difference in condition between the sexes, males averaged a 17 % greater PCB concentration compared with females. Results from the laboratory experiment indicated that males were significantly more active than females. The observed sex difference in PCB concentrations was not due to female sea lampreys releasing eggs at spawning because the sea lamprey is semelparous, and we caught the sea lampreys before spawning. Rather, we attributed the sex difference in PCB concentrations to a greater rate of energy expenditure in males compared with females. We proposed that this greater rate of energy expenditure was likely due to greater activity. Our laboratory experiment results supported this hypothesis. A greater resting metabolic rate may also have contributed to a greater rate of energy expenditure. Our findings should eventually be applicable toward improving control of sea lamprey, a pest responsible for considerable damage to fisheries in lakes where it is not native.

Michigan↗
USGS2025

Reframing fish passage prioritization for human nutrition outcomes

Water control infrastructure forms barriers that fragment river habitats, reducing aquatic biodiversity and the ecosystem services it provides. Irrigation infrastructure, for example, although implemented to support food production, highlights problematic trade-offs against wild food systems like inland fisheries which are a critical food resource for tens of millions of people, particularly in tropical countries. To reduce fragmentation at a broad range of barriers, fish passage technology is sometimes implemented to support migrating fish, aided by frameworks designed to prioritize barriers for remediation. This study critically evaluated 93 fish passage barrier prioritization frameworks globally to explore how they could strategically guide fish passage investments in tropical contexts and identify criteria relevant to delivering on nutrition security outcomes. Results showed prioritization frameworks were ill-equipped to support the broader human development goals that may drive fish passage investments in tropical countries, such as supporting human nutrition under United Nations Sustainable Development Goal (SDG) 2: Zero Hunger. Tropical contexts were underrepresented despite substantial recent fish passage investment, whereas temperate and conservation focused frameworks, particularly from North America, dominated. These findings prompt reflection on the inherent biases in fish passage barrier prioritization frameworks and criteria. Improving understanding of and collaboration with local partners to integrate SDG 2 into future prioritization frameworks could improve fish passage infrastructure and help support better nutrition and food production for communities.

Environmental Management↗
USGS2026

Poor population recovery of Lake Washington Chinook Salmon (Oncorhynchus tshawytscha) in Pacific Northwestern USA may be associated with disease caused by Ceratonova shasta in an urban-influenced watershed

Understanding the effects of anthropogenic changes on fish disease is vital for supporting mitigative actions for fisheries population recovery. The Lake Washington watershed in the Pacific Northwestern United States is influenced by high urban development and climate change, compromising the sustainability of anadromous salmon. We investigated Ceratonova shasta , a myxozoan parasite, in Chinook Salmon Oncorhynchus tshawytscha to determine the impacts of C. shasta -induced enteronecrosis during salmon freshwater migrations within this watershed. All sampled adult Chinook Salmon returning to an enhancement hatchery to spawn were infected with genotype I C. shasta with a high prevalence of severe enteritis and enteronecrosis. Parasite loads and associated pathology were more severe in adult fish succumbing to prespawn mortality than in fish that spawned. Natural prespawn mortality of Chinook Salmon in the Cedar River was also associated with high C. shasta loads. Sentinel exposure studies with Chinook Salmon juveniles in the spring and fall demonstrated high levels of C. shasta genotype II actinospores in the Lake Washington Ship Canal, a human engineered canal that salmon must traverse in their freshwater migrations from the Puget Sound. The sentinel juvenile Chinook Salmon succumbed to clinical disease and high mortality from genotype II C. shasta , suggesting that these stocks have high susceptibility to this genotype. The results show that both genotypes I and II pose disease risks to adult and juvenile stages of Chinook Salmon in the watershed, and that the Lake Washington Ship Canal could be a C. shasta ‘hot spot’ for genotype II that may increase disease risk for juveniles during smolt emigration.

Washington↗
USGS2009

Population synchrony of a native fish across three Laurentian Great Lakes: Evaluating the effects of dispersal and climate

Climate and dispersal are the two most commonly cited mechanisms to explain spatial synchrony among time series of animal populations, and climate is typically most important for fishes. Using data from 1978-2006, we quantified the spatial synchrony in recruitment and population catch-per-unit-effort (CPUE) for bloater (Coregonus hoyi) populations across lakes Superior, Michigan, and Huron. In this natural field experiment, climate was highly synchronous across lakes but the likelihood of dispersal between lakes differed. When data from all lakes were pooled, modified correlograms revealed spatial synchrony to occur up to 800 km for long-term (data not detrended) trends and up to 600 km for short-term (data detrended by the annual rate of change) trends. This large spatial synchrony more than doubles the scale previously observed in freshwater fish populations, and exceeds the scale found in most marine or estuarine populations. When analyzing the data separately for within- and between-lake pairs, spatial synchrony was always observed within lakes, up to 400 or 600 km. Conversely, between-lake synchrony did not occur among short-term trends, and for long-term trends, the scale of synchrony was highly variable. For recruit CPUE, synchrony occurred up to 600 km between both lakes Michigan and Huron (where dispersal was most likely) and lakes Michigan and Superior (where dispersal was least likely), but failed to occur between lakes Huron and Superior (where dispersal likelihood was intermediate). When considering the scale of putative bloater dispersal and genetic information from previous studies, we concluded that dispersal was likely underlying within-lake synchrony but climate was more likely underlying between-lake synchrony. The broad scale of synchrony in Great Lakes bloater populations increases their probability of extirpation, a timely message for fishery managers given current low levels of bloater abundance. ?? Springer-Verlag 2009.

Oecologia↗
USGS2019

Latitude and daily-weather effects on gobbling activity of wild turkeys in Mississippi

Weather has been recognized as a density independent factor influencing the abundance, distribution, and behavior of vertebrates. Male wild turkeys’ ( Meleagris gallopavo ) breeding behavior includes vocalizations and courtship displays to attract females, the phenology of which can vary with latitude. State biologists design spring turkey-hunting season frameworks centered on annual vocalization patterns to maximize hunter engagement. The Mississippi Department of Wildlife, Fisheries, and Parks has traditionally instituted a statewide, 7-week, spring harvest season. However, hunters routinely argue that different peaks in gobbling activity across the state exist. The objective of this study was to determine whether differences in peak gobbling activity existed across a latitudinal gradient of Mississippi and assess the effect of weather on gobbling. During 2008 and 2009, we conducted a statewide gobbling survey. We used generalized additive mixed models to describe the probability and frequency of gobbling activity within northern and southern regions of the state. We also investigated the effect of daily weather conditions on gobbling activity. Our results revealed an approximate 10–14-day difference in peak gobbling activity between southern and northern Mississippi. The majority of all gobbling activity occurred within the current spring harvest framework. Perhaps more importantly, gobbling activity was more prevalent on days of regionally dry conditions (i.e., less humid) according to the Spatial Synoptic Classification. Our results provide information on gobbling activity phenology relative to hunting-season dates and weather-response information. Our approach may be particularly applicable in states with relatively shorter seasons or highly variable daily weather conditions that moderate gobbling frequency.

Mississippi↗
USGS2001

The introduction of nonnative fish into wilderness lakes: Good intentions, conflicting mandates, and unintended consequences

Because they have the potential to provide the best remaining standards of relatively unmodified landscapes, protected areas in North America (such as wilderness areas and national parks) have tremendous ecological and scientific value (Cole and Landres 1996). Although the montane ecosystems of western North America are particularly well represented in this complex of protected lands, aquatic habitats within these protected areas are often subject to management practices that are inconsistent with the goal of maintaining natural processes. The most prevalent of these practices is the introduction of salmonid fishes (such as trout) into historically fishless ecosystems to create recreational fisheries.

Ecosystems↗
USGS2005

Spatial relationships between an introduced snapper and native goatfishes on Hawaiian reefs

It has been suggested that the introduced blueline snapper (Lutjanus kasmira, Family: Lutjanidae) may adversely affect populations of native fishery species in Hawai'i through competition for spatial or dietary resources, or through predation on young fish. We studied the habitat use patterns of L. kasmira and several native reef fish species using direct observation by SCUBA divers. Habitat use patterns of the yellowtail goatfish (Mulloidichthys vanicolensis, Family: Mullidae) were most similar to those of L. kasmira. Both species were primarily found low in the water column and were closely associated with areas of vertical relief. Individual M. vanicolensis were found higher in the water column when L. kasmirawere present, but L. kasmira were not similarly affected by M. vanicolensis. This finding suggests asymmetrical competition for shelter, in which the dominant L. kasmira displaces M. vanicolensis farther into the water column. This displacement from the protection of the reef could increase the vulnerability of M. vanicolensisto predators and fishers. ?? Springer 2005.

Biological Invasions↗
USGS2020

Walleye growth declines following zebra mussel and Bythotrephes invasion

Invasive species represent a threat to aquatic ecosystems globally; however, impacts can be heterogenous across systems. Documented impacts of invasive zebra mussels ( Dreissena polymorpha ) and spiny water fleas ( Bythotrephes cederströmii ; hereafter Bythotrephes ) on native fishes are variable and context dependent across locations and time periods. Here, we use a hierarchical Bayesian analysis of a 35-year dataset on two fish species from 9 lakes to demonstrate that early life growth of ecologically important fishes are influenced by these aquatic invasive species. Walleye ( Sander vitreus ) in their first year of life grew more slowly in the presence of either invader after correcting for temperature (measured by degree days), and were on average 12 or 14% smaller at the end of their first summer following invasion by Bythotrephes or zebra mussels, respectively. Yellow perch ( Perca flavescens ) growth was less affected by invasion. Yellow perch on average grew more slowly in their first year of life following invasion by zebra mussels, although this effect was not statistically distinguishable from zero. Early life growth of both walleye and yellow perch was less tightly coupled to degree days in invaded systems, as demonstrated by increased variance surrounding the degree day-length relationship. Smaller first-year size is related to walleye survival and recruitment to later life stages and has important implications for lake food webs and fisheries management. Future research quantifying effects of zebra mussels and Bythotrephes on other population-level processes and across a wider gradient of lake types is needed to understand the mechanisms driving observed changes in walleye growth.

Minnesota↗
USGS2023

Assessing the suitability of YY males and ZZ females as an invasive species population control method across life histories

Natural resource managers use tools to control invasive species. In theory, stocking YY males or ZZ females would allow managers to skew sex ratios until populations collapse. In combination with other suppression methods, such as removal, this approach could be incorporated into Integrated Pest Management plans. For example, fishery managers have stocked YY males to control isolated non-native brook trout ( Salvelinus fontinalis ) populations. However, life histories and demographic factors (e.g., lifespans) vary across species and could affect the feasibility of skewing sex ratios as an effective control strategy for a given population. Likewise, some species may have sex determinations that do not allow population control through sex-skewing methods. We compared five representative aquatic invasive species with global invasion ranges for potential control by skewing the sex ratio through closed population simulations: red swamp crayfish (Procambarus clarkii ), zebra mussels ( Dreissena polymorpha ), lake trout ( Salvelinus namaycush) , silver carp ( Hypophthalmichthys molitrix ), and Nile tilapia ( Oreochromis niloticus ). We determined that Nile tilapia, red swamp crayfish, and zebra mussels would be the most suitable to control through skewing the sex ratio assuming appropriate sex determination exists in the species. Lake trout could be eliminated by stocking YY males but would require either long stocking periods or high stocking numbers because of the long lifespan of the species. Silver carp populations were more difficult to crash because they live longer and produce many recruits. Broadly, these patterns demonstrated that short lived species lend themselves to control by skewing the sex ratio.

Biological Invasions↗
USGS2010

The present and future role of coastal wetland vegetation in protecting shorelines: Answering recent challenges to the paradigm

For more than a century, coastal wetlands have been recognized for their ability to stabilize shorelines and protect coastal communities. However, this paradigm has recently been called into question by small-scale experimental evidence. Here, we conduct a literature review and a small meta-analysis of wave attenuation data, and we find overwhelming evidence in support of established theory. Our review suggests that mangrove and salt marsh vegetation afford context-dependent protection from erosion, storm surge, and potentially small tsunami waves. In biophysical models, field tests, and natural experiments, the presence of wetlands reduces wave heights, property damage, and human deaths. Meta-analysis of wave attenuation by vegetated and unvegetated wetland sites highlights the critical role of vegetation in attenuating waves. Although we find coastal wetland vegetation to be an effective shoreline buffer, wetlands cannot protect shorelines in all locations or scenarios; indeed large-scale regional erosion, river meandering, and large tsunami waves and storm surges can overwhelm the attenuation effect of vegetation. However, due to a nonlinear relationship between wave attenuation and wetland size, even small wetlands afford substantial protection from waves. Combining man-made structures with wetlands in ways that mimic nature is likely to increase coastal protection. Oyster domes, for example, can be used in combination with natural wetlands to protect shorelines and restore critical fishery habitat. Finally, coastal wetland vegetation modifies shorelines in ways (e.g. peat accretion) that increase shoreline integrity over long timescales and thus provides a lasting coastal adaptation measure that can protect shorelines against accelerated sea level rise and more frequent storm inundation. We conclude that the shoreline protection paradigm still stands, but that gaps remain in our knowledge about the mechanistic and context-dependent aspects of shoreline protection.

Climatic Change↗
USGS2012

A stakeholder project to model water temperature under future climate scenarios in the Satus and Toppenish watersheds of the Yakima River Basinin Washington, USA

The goal of this study was to support an assessment of the potential effects of climate change on select natural, social, and economic resources in the Yakima River Basin. A workshop with local stakeholders highlighted the usefulness of projecting climate change impacts on anadromous steelhead ( Oncorhynchus mykiss) , a fish species of importance to local tribes, fisherman, and conservationists. Stream temperature is an important environmental variable for the freshwater stages of steelhead. For this study, we developed water temperature models for the Satus and Toppenish watersheds, two of the key stronghold areas for steelhead in the Yakima River Basin. We constructed the models with the Stream Network Temperature Model (SNTEMP), a mechanistic approach to simulate water temperature in a stream network. The models were calibrated over the April 15, 2008 to September 30, 2008 period and validated over the April 15, 2009 to September 30, 2009 period using historic measurements of stream temperature and discharge provided by the Yakama Nation Fisheries Resource Management Program. Once validated, the models were run to simulate conditions during the spring and summer seasons over a baseline period (1981–2005) and two future climate scenarios with increased air temperature of 1°C and 2°C. The models simulated daily mean and maximum water temperatures at sites throughout the two watersheds under the baseline and future climate scenarios.

Washington↗
USGS2017

Assessing the impact of stocking northern-origin hatchery brook trout on the genetics of wild populations in North Carolina

The release of hatchery-origin fish into streams with endemics can degrade the genetics of wild populations if interbreeding occurs. Starting in the 1800s, brook trout descendent from wild populations in the northeastern United States were stocked from hatcheries into streams across broad areas of North America to create and enhance fishery resources. Across the southeastern United States, many millions of hatchery-origin brook trout have been released into hundreds of streams, but the extent of introgression with native populations is not well resolved despite large phylogeographic distances between these groups. We used three assessment approaches based on 12 microsatellite loci to examine the extent of hatchery introgression in 406 wild brook trout populations in North Carolina. We found high levels of differentiation among most collections (mean F ′ ST = 0.718), and among most wild collections and hatchery strains (mean F ′ ST = 0.732). Our assessment of hatchery introgression was consistent across the three metrics, and indicated that most wild populations have not been strongly influenced by supplemental stocking. However, a small proportion of wild populations in North Carolina appear to have been strongly influenced by stocked conspecifics, or in some cases, may have been founded entirely by hatchery lineages. In addition, we found significant differences in the apparent extent of hatchery introgression among major watersheds, with the Savannah River being the most strongly impacted. Conversely, populations in the Pee Dee River watershed showed little to no evidence of hatchery introgression. Our study represents the first large-scale effort to quantify the extent of hatchery introgression across brook trout populations in the southern Appalachians using highly polymorphic microsatellite markers.

North Carolina↗
USGS2021

Landscape and stocking effects on population genetics of Tennessee Brook Trout

Throughout their range, Brook Trout ( Salvelinus fontinalis ) occupy thousands of disjunct drainages with varying levels of disturbance, which presents substantial challenges for conservation. Within the southern Appalachian Mountains, fragmentation and genetic drift have been identified as key threats to the genetic diversity of the Brook Trout populations. In addition, extensive historic stocking of domestic lineages of Brook Trout to augment fisheries may have eroded endemic diversity and impacted locally adapted populations. We used 12 microsatellite loci to describe patterns of genetic diversity within 108 populations of wild Brook Trout from Tennessee and used linear models to explore the impacts of land use, drainage area, and hatchery stockings on metrics of genetic diversity, effective population size, and hatchery introgression. We found levels of within-population diversity varied widely, although many populations showed very limited diversity. The extent of hatchery introgression also varied across the landscape, with some populations showing high affinity to hatchery lineages and others appearing to retain their endemic character. However, we found relatively weak relationships between genetic metrics and landscape characteristics, suggesting that contemporary landscape variables are not strongly related to observed patterns of genetic diversity. We consider this result to reflect both the complex history of these populations and the challenges associated with accurately defining drainages for each population. Our study highlights the importance of genetic data to guide management decisions, as complex processes interact to shape the genetic structure of populations and make it difficult to infer the status of unsampled populations.

Tennessee↗
USGS2017

An evaluation of silver-stage American Eel conspecific chemical cueing during outmigration

American Eel Anguilla rostrata abundance has declined in recent decades, in part because sexually maturing, silver-stage adults, outmigrating from freshwater to oceanic spawning grounds, encounter migratory blockades or perish when passing through active hydroelectric turbines. To help improve downstream passage effectiveness and increase survival rates, the role of silver-stage American Eel conspecific chemical cueing during outmigration was investigated using a new type of bioassay. Inside a laboratory flume, downstream-swimming eels were exposed to both live (putative attractant) and dead (putative repellent) conspecific washings to determine whether their trajectory of downstream movement, level of activity, or time spent inside targeted areas of the arena changed after exposure. Silver eels were not attracted to or repulsed by either odor, as none of five scoring metrics indicated a behavioral response. Results did not support the hypothesis that conspecific chemical cueing is a mechanism for downstream migration coordination or danger avoidance; however responses may not have been readily apparent in this type of assay. Fisheries managers may opt to focus future research on more feasible restoration efforts using alternate experimental designs to remedy this ecological issue.

Environmental Biology of Fishes↗
USGS2018

Intraspecific differences in morphology correspond to differential spawning habitat use in two riverine catostomid species

Maintaining intraspecific diversity is an important goal for fisheries conservation and recovery actions. While ecomorphological studies have demonstrated intraspecific diversity related to feeding or flow regime, there has been little assessment of such variation in regard to spawning habitat. We evaluated the relationship between individual morphology of Robust Redhorse and Notchlip Redhorse and variables describing the spawning habitat from which they were captured, such as current velocity, depth, and substrate particle size. Robust Redhorse ( n = 58) and Notchlip Redhorse ( n = 43) were captured from spawning aggregations in the lower Savannah River, South Carolina-Georgia using prepositioned grid electrofishers. They were then measured and photographed before being released. We constructed a truss network using digitized landmarks on each of the photographs. Relationships between the morphological and environmental datasets were assessed using canonical correlation analysis. In both species, these morphological predictors were correlated primarily to depth, though current velocity also contributed to the environmental canonical score for Robust Redhorse. Robust Redhorse captured from the deeper locations with higher current velocities had heads with lower aspect ratio compared to individuals captured from shallower areas. Notchlip Redhorse from shallower areas were deeper-bodied and had shorter trunks than counterparts from deeper areas. These differences suggest that ensuring spawning habitat heterogeneity may be an important component to conserving intraspecific diversity, particularly in systems where such habitat is limiting.

Georgia, South Carolina↗
USGS2023

Can angler-assisted broodstock collection programs improve harvest rates of hatchery-produced steelhead?

Fish that exhibit high foraging activity or bold behavior can be particularly vulnerable to angling. If these traits are heritable, selection through harvest can drive phenotypic change, eventually rendering a target population less vulnerable to angling and consequently impacting the quality of the fishery. In this study, we used parental-based tags to investigate whether vulnerability to angling might be heritable in steelhead trout ( Oncorhynchus mykiss ) spawned at a hatchery in western Oregon, USA. We found modest evidence to support the hypothesis that vulnerability to angling is a heritable trait in steelhead. However, our data unexpectedly revealed that steelhead collected with in-river traps produced nearly twice as many adult offspring as steelhead collected by anglers. This difference in adult-to-adult production is explained in part through lower egg-to-fry survival of steelhead produced with angler-caught broodstock, possibly related to collection stress and greater time in captivity experienced by angler-caught broodstock. Our findings suggest that managers could improve broodstock fitness and program efficiencies by preferentially spawning fish collected with traps, and limiting use of broodstock collected by anglers. Additional research is needed to identify mechanisms contributing to higher juvenile mortality of steelhead produced with angler-caught broodstock.

Oregon↗
USGS2023

Scale-dependent tradeoffs between habitat and time in explaining Alligator Gar (Atractosteus spatula) movement

Ecological theory predicts that movement by riverine fishes at the population level is characterized by both stationary and mobile individuals together creating a leptokurtic distribution of movement distances. However, studies testing this theory typically ignore spatial heterogeneity in riverscapes, and the theory has not been tested using Alligator Gar ( Atractosteus spatula ), a species of growing interest among anglers and fisheries managers alike. We characterized movements and habitat associations of Alligator Gar in the Brazos River, Texas, at fine (every 2 h for 24 h) and coarse (every month for 16 months) spatiotemporal scales. We tested for the presence of leptokurtosis and relationships between movement distance, habitat dissimilarity, and time-at-large using multivariate and univariate statistical approaches. Dispersal by Alligator Gar revealed leptokurtosis at the coarse scale but not the fine scale. At the fine scale, mixed effects quantile regression revealed there was no relationship between habitat dissimilarity and dispersal distance, but dispersal was positively correlated with time. At the coarse scale, dispersal was positively correlated with increased habitat dissimilarity and time, but only for the most mobile individuals. Our work suggests that short-term movements by riverine Alligator Gar during warm seasons and at base flows increased with time but were unrelated to habitat, and long-term movements over an annual cycle during warm season flow pulses revealed highly mobile members of the population accessed distant and novel floodplain environments.

Environmental Biology of Fishes↗
USGS2014

Can mercury in fish be reduced by water level management? Evaluating the effects of water level fluctuation on mercury accumulation in yellow perch ( Perca flavescens )

Mercury (Hg) contamination of fisheries is a major concern for resource managers of many temperate lakes. Anthropogenic Hg contamination is largely derived from atmospheric deposition within a lake’s watershed, but its incorporation into the food web is facilitated by bacterial activity in sediments. Temporal variation in Hg content of fish (young-of-year yellow perch) in the regulated lakes of the Rainy–Namakan complex (on the border of the United States and Canada) has been linked to water level (WL) fluctuations, presumably through variation in sediment inundation. As a result, Hg contamination of fish has been linked to international regulations of WL fluctuation. Here we assess the relationship between WL fluctuations and fish Hg content using a 10-year dataset covering six lakes. Within-year WL rise did not appear in strongly supported models of fish Hg, but year-to-year variation in maximum water levels (∆maxWL) was positively associated with fish Hg content. This WL effect varied in magnitude among lakes: In Crane Lake, a 1 m increase in ∆maxWL from the previous year was associated with a 108 ng increase in fish Hg content (per gram wet weight), while the same WL change in Kabetogama was associated with only a 5 ng increase in fish Hg content. In half the lakes sampled here, effect sizes could not be distinguished from zero. Given the persistent and wide-ranging extent of Hg contamination and the large number of regulated waterways, future research is needed to identify the conditions in which WL fluctuations influence fish Hg content.

Ecotoxicology↗