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At least 1,441 records · Page 80Linked to original sources
USGS2018

Lower lethal temperatures for nonnative freshwater fishes in Everglades National Park, Florida

Temperature is an important factor that shapes biogeography and species composition. In southern Florida, the tolerance of nonnative freshwater fishes to low temperatures is a critical factor in delineating their geographic spread. In this study, we provide empirical information on experimentally derived low-temperature tolerance limits of Banded Cichlid Heros severus and Spotfin Spiny Eel Macrognathus siamensis, two nonnative Everglades fishes that were lacking data, and African Jewelfish Hemichromis letourneuxi and Mayan Cichlid Cichlasoma urophthalmus, species for which previous results were derived from studies with small sample sizes. We also provide a literature review summarizing the current state of knowledge of low-temperature tolerances for all 17 nonnative freshwater fishes that have been found in Everglades National Park. Mean lower lethal temperature tolerances ranged from 4°C (Orinoco Sailfin Catfish Pterygoplichthys multiradiatus) to 16.1°C (Butterfly Peacock Bass Cichla ocellaris). These low-temperature limits may inform the understanding of the ecological role or influence of nonnative fishes and may lead to potential management opportunities and applications.

Florida↗
USGS2019

Understanding fish assemblage structure in lentic ecosystems: Relative effects of abiotic factors and management legacies

We investigated associations of fish assemblages and habitat characteristics (e.g., morphology and water chemistry) from 45 natural lakes and reservoirs in Iowa to determine whether species or trophic guild composition and environmental correlations were concordant between waterbodies of different origins. Overall, fish assemblage composition between natural lakes and reservoirs was consistently dissimilar based on a permutational multivariate ANOVA. Species composition from nonmetric multidimensional scaling ordinations for reservoirs was correlated with a variety of limnological and physical characteristics, whereas species composition and trophic composition of natural lakes were weakly associated with habitat characteristics. Species richness was positively related to waterbody and watershed size for reservoirs but not for natural lakes. Conversely, species richness was negatively correlated with increasing eutrophic conditions in natural lakes but not in reservoirs. Overall, distinct differences in assemblage composition were observed between natural and artificial lentic ecosystems and may have resulted from underlying differences in limnological, physical, and anthropogenic influences between systems. Dissimilar management legacies between waterbody types, such as limited or no stocking of nonrecreationally important species and the use of piscicides, may have additionally had overriding effects on the observed assemblage–environmental relationships. For instance, lower trophic richness and species richness in reservoirs appeared to have resulted from replacement of a diversity of small-bodied native species by relatively few commonly stocked sport fishes. Our results emphasize the need to consider waterbody origin and the potential influence of historical or current management strategies on fish assemblage characterization and subsequent inferences made from environmental correlations.

Iowa↗
USGS2019

Nonlethal detection of Asian fish tapeworm in the federally-endangered Humpback Chub using a molecular screening tool

Optimal spawning habitat of federally endangered Humpback Chub Gila cypha exists within the Little Colorado River; however, temperatures in the Little Colorado River are also ideal for proliferation of the invasive pathogenic Asian fish tapeworm Schyzocotyle acheilognathi . The current standard for positive identification of the parasite is necropsy and visual examination of the gut via microscopy, a methodology undesirable for assessing infection in endangered fishes. A swab taken at the rectum of the fish and analyzed using a novel DNA primer targeting the cestode cytochrome oxidase I subunit mtDNA gene region offers a convenient nonlethal sampling tool. To validate the nonlethal methodology, primer sensitivity (51.9%) and specificity (79.5%) were calculated by exposing captive fish to the parasite and comparing results using the lethal standard method (i.e., visual examination). Subsequently, we utilized this nonlethal methodology to address prevalence of infection and infection frequency across a range of size-classes in a wild population of Humpback Chub and addressed possible patterns and mechanisms of infection in the Little Colorado River. When wild Humpback Chub were screened for infection prevalence in spring 2015 (21.4%, n = 140) and fall 2015 (6.6%, n = 258), the relative frequency of infection was highest in juveniles and subadult fish (200–300 mm). Elevated levels of infection near the major spawning grounds of Humpback Chub in the Little Colorado River promote parasitic infection, which may continue to persist without treatment or actions to control infections. We demonstrated that rectal swabs, in conjunction with PCR and primer-specific identification, offer a time-efficient nonlethal method to detect infection of Asian fish tapeworm in an endangered fish.

Transactions of the American Fisheries Society↗
USGS2022

Assessment of native fish passage through Brandon Road Lock and Dam, Des Plaines River, Illinois, using fin ray microchemistry

This study examined evidence of native fish passage through Brandon Road Lock and Dam (BRLD) on the Des Plaines River, Illinois, in light of proposed modifications to prevent the upstream passage of invasive carps. Direct evidence of upstream passage by native fishes at BRLD is lacking and could help to inform assessment of the impacts of barrier technology installation. Fin ray microchemistry was used to assess upstream BRLD passage in the native taxa Centrarchidae, Catostomidae, Ictaluridae, and Lepisosteidae. The fin ray edge strontium : calcium ratio (Sr:Ca) of fish sampled from the Des Plaines River upstream of BRLD and in rivers downstream of BRLD was used to characterize ranges of river-specific fin ray Sr:Ca for each taxon. These were applied to Sr:Ca data along a transect from fin ray core to edge to infer the environmental history of individual fish that were captured upstream from BRLD and to estimate the proportion of fish that had passed upstream through BRLD. Depending on the taxon, 6–37% of individuals sampled upstream from BRLD exhibited fin ray Sr:Ca indicating prior residency in rivers downstream of BRLD and therefore upstream passage through BRLD. Upstream passage was indeterminate for 19–91% of individuals in each taxon due to uncertainty in environmental history inferred from fin ray Sr:Ca. These results provide the first definitive evidence of upstream native fish passage at BRLD and suggest that the installation of barrier technology could have an impact on native fish.

Illinois↗
USGS2010

Traveling around Cape Horn: Otolith chemistry reveals a mixed stock of Patagonian hoki with separate Atlantic and Pacific spawning grounds

Trace element fingerprints of edge and core regions in otoliths from 260 specimens of Patagonian hoki, Macruronus magellanicus L??nnberg, 1907, were analyzed by LA-ICPMS to reveal whether this species forms one or more population units (stocks) in the Southern Oceans. Fish were caught on their spawning grounds in Chile and feeding grounds in Chile and the Falkland Islands. Univariate and multivariate analyses of trace element concentrations in the otolith edges, which relate to the adult life of fish, could not distinguish between Atlantic (Falkland) and Pacific (Chile) hoki. Cluster analyses of element concentrations in the otolith edges produced three different clusters in all sample areas indicating high mixture of the stocks. Cluster analysis of trace element concentrations in the otolith cores, relating to juvenile and larval life stages, produced two separate clusters mainly distinguished by 137 Ba concentrations. The results suggest that Patagonian hoki is a highly mixed fish stock with at least two spawning grounds around South America. ?? 2009 Elsevier B.V.

Fisheries Research↗
USGS2012

Effects of activity and energy budget balancing algorithm on laboratory performance of a fish bioenergetics model

We evaluated the performance of the Wisconsin bioenergetics model for lake trout Salvelinus namaycush that were fed ad libitum in laboratory tanks under regimes of low activity and high activity. In addition, we compared model performance under two different model algorithms: (1) balancing the lake trout energy budget on day t based on lake trout energy density on day t and (2) balancing the lake trout energy budget on day t based on lake trout energy density on day t + 1. Results indicated that the model significantly underestimated consumption for both inactive and active lake trout when algorithm 1 was used and that the degree of underestimation was similar for the two activity levels. In contrast, model performance substantially improved when using algorithm 2, as no detectable bias was found in model predictions of consumption for inactive fish and only a slight degree of overestimation was detected for active fish. The energy budget was accurately balanced by using algorithm 2 but not by using algorithm 1. Based on the results of this study, we recommend the use of algorithm 2 to estimate food consumption by fish in the field. Our study results highlight the importance of accurately accounting for changes in fish energy density when balancing the energy budget; furthermore, these results have implications for the science of evaluating fish bioenergetics model performance and for more accurate estimation of food consumption by fish in the field when fish energy density undergoes relatively rapid changes.

Transactions of the American Fisheries Society↗
USGS2013

Fish assemblages in borrow-pit lakes of the Lower Mississippi River

Borrow-pit lakes encompass about a third of the lentic water habitats (by area) in the active floodplain of the Lower Mississippi River, yet little is known about their fish assemblages. We investigated whether fish assemblages supported by borrow-pit lakes resembled those in oxbow lakes to help place the ecological relevance of borrow-pit lakes in context with that of natural floodplain lakes. In all, we collected 75 fish species, including 65 species in eight borrow-pit lakes, 52 species in four riverside oxbow lakes, and 44 species in eight landside oxbow lakes. Significant differences in several species richness metrics were evident between borrow-pit lakes and landside oxbow lakes but not between borrow-pit lakes and riverside oxbow lakes. All three lake types differed in fish assemblage composition. Borrow-pit lakes and riverside oxbow lakes tended to include a greater representation of fish species that require access to diverse environments, including lentic, lotic, and palustrine habitats; fish assemblages in landside oxbow lakes included a higher representation of lacustrine species. None of the fish species collected in borrow-pit lakes was federally listed as threatened or endangered, but several were listed as species of special concern by state governments in the region, suggesting that borrow-pit lakes provide habitat for sensitive riverine and wetland fish species. Differences in fish assemblages among borrow-pit lakes were linked to engineered morphologic features, suggesting that diversity in engineering can contribute to diversity in fish assemblages; however, more research is needed to match engineering designs with fish assemblage structures that best meet conservation needs.

Lower Mississippi River↗
USGS2016

Upstream movements of Atlantic Salmon in the Lower Penobscot River, Maine following two dam removals and fish passage modifications

The Penobscot River Restoration Project (PRRP), to be completed in 2016, involved an extensive plan of dam removal, increases in hydroelectric capacity, and fish passage modifications to increase habitat access for diadromous species. As part of the PRRP, Great Works and Veazie dams were removed, making Milford Dam the first impediment to federally endangered Atlantic Salmon Salmo salar . Upstream habitat access for Atlantic Salmon is dependent upon successful and timely passage at Milford Dam because nearly all suitable spawning habitat is located upstream. In 2014 and 2015, a total of 73 adult salmon were radio-tagged to track their upstream movements through the Penobscot River to assess potential delays at (1) the dam remnants, (2) the confluence of the Stillwater Branch and the main stem of the Penobscot River below the impassable Orono Dam, and (3) the Milford Dam fish lift (installed in 2014). Movement rates through the dam remnants and the Stillwater confluence were comparable to open river reaches. Passage efficiency of the fish lift was high in both years (95% and 100%). However, fish experienced long delays at Milford Dam, with approximately one-third of fish taking more than a week to pass in each year, well below the Federal Energy Regulatory Commission passage standard of 95% within 48 h. Telemetry indicates most fish locate the fishway entrance within 5 h of arrival and were observed at the entrance at all hours of the day. These data indicate that overall transit times through the lower river were comparable to reported movement rates prior to changes to the Penobscot River due to the substantial delays seen at Milford Dam. The results of this study show that while adult Atlantic Salmon locate the new fish lift entrance quickly, passage of these fish was significantly delayed under 2014–2015 operations.

Maine↗
USGS2025

Seasonal movements of nonnative White Catfish in the Penobscot River estuary

Objective White Catfish Ameiurus catus has been introduced to coastal watersheds across the United States. In the Penobscot River, Maine, this species has become increasingly common in upstream habitats that have been made accessible by recent dam removals. We characterized the movements of White Catfish to understand the temporal variation in their movement patterns and contextualize these findings within the recent changes in watershed connectivity. Methods We captured and tagged 10 adult White Catfish (mean fork length = 271 mm) with acoustic transmitters in the lower Penobscot River in July 2022. The movements of the tagged fish were monitored through April 2023 with a large network of stationary receivers. Results The tagged catfish were detected up to 6 km upstream and 31 km downstream from the release site. The total distance that was traveled by individuals ranged from 0 to 154 km during the study. Fall and spring movements were associated with changes in river flow and water temperature, but fish were relatively stationary from December through March, when at least five individuals were assumed to have overwintered in lower river tributaries. Conclusion Our results show that individual White Catfish may move considerable distances within large river systems and that these movements are potentially facilitated by changing river conditions. Collectively, this study fills a long-standing knowledge gap about the movement ecology of this species, adds context to help explain a recent increase in observations within their introduced range, and shows how changes in river conditions may be used to predict when and where these fish will move within a tidal system.

Maine↗
USGS2023

Linking ecosystem processes to consumer growth rates: Gross primary productivity as a driver of freshwater fish somatic growth in a resource-limited river

Individual growth can exert strong controls on population dynamics and be constrained by resource acquisition rates. Difficulty in accurately quantifying resource availability over large spatial extents and at high temporal frequency often limits attempts to understand the extent that resources limit individual growth. Daily estimates of stream metabolism, including gross primary productivity (GPP), are increasingly available but have not, to our knowledge, been linked to fish growth. Here we examine how GPP, water temperature, high flow and turbidity are linked to spatiotemporal variation in growth of flannelmouth sucker (Catostomus latipinnis). We fit state space growth models to six years of mark-recapture data collected in four river reaches spanning 300 river kilometers. Consistent with past research in this system, we find that water temperature is the dominant driver of spatiotemporal variation in growth. However, we also find that GPP is strongly linked to fish growth. Fish growth is likely to be linked to stream metabolism in other systems where overall productivity, not the quality of primary producers, limits the food webs that support fish growth.

Arizona↗
USGS2004

Swimming performance of upstream migrant fishes in open-channel flow: A new approach to predicting passage through velocity barriers

The ability to traverse barriers of high-velocity flow limits the distributions of many diadromous and other migratory fish species, yet very few data exist that quantify this ability. We provide a detailed analysis of sprint swimming ability of six migratory fish species (American shad (Alosa sapidissima), alewife (Alosa pseudoharengus), blueback herring (Alosa aestivalis), striped bass (Morone saxatilis), walleye (Stizostedion vitreum), and white sucker (Catostomus commersoni)) against controlled water velocities of 1.5-4.5 m??s-1 in a large, open-channel flume. Performance was strictly voluntary: no coercive incentives were used to motivate fish to sprint. We used these data to generate models of maximum distance traversed, taking into account effects of flow velocity, body length, and temperature. Although the maximum distance traversed decreased with increasing velocity, the magnitude of this effect varied among species. Other covariate effects were likewise variable, with divergent effects of temperature and nonuniform length effects. These effects do not account for all of the variability in performance, however, and behavioral traits may account for observed interspecific differences. We propose the models be used to develop criteria for fish passage structures, culverts, and breached dams.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2012

Structure of marine predator and prey communities along environmental gradients in a glaciated fjord

Spatial patterns of marine predator communities are influenced to varying degrees by prey distribution and environmental gradients. We examined physical and biological attributes of an estuarine fjord with strong glacier influence to determine the factors that most influence the structure of predator and prey communities. Our results suggest that some species, such as walleye pollock ( Theragra chalcogramma ), black-legged kittiwake ( Rissa tridactyla ), and glaucous-winged gull ( Larus glaucescens ), were widely distributed across environmental gradients, indicating less specialization, whereas species such as capelin ( Mallotus villosus ), harbor seal ( Phoca vitulina ), and Kittlitz's murrelet ( Brachyramphus brevirostris ) appeared to have more specialized habitat requirements related to glacial influence. We found that upper trophic level communities were well correlated with their mid trophic level prey community, but strong physical gradients in photic depth, temperature, and nutrients played an important role in community structure as well. Mid-trophic level forage fish communities were correlated with the physical gradients more closely than upper trophic levels were, and they showed strong affinity to tidewater glaciers. Silica was closely correlated with the distribution of fish communities, the mechanisms of which deserve further study.

Alaska↗
USGS1973

Endrin uptake and release by fingerling channel catfish (Ictalurus punctatus)

Fingerling channel catfish ( Ictalurus punctatus ) offered diets containing 0.04–4.0 μg endrin/g food (dry weight) rapidly accumulated the pesticide. Amounts in the tissues were directly proportional to amounts in the food. Dietary endrin had no measurable effect on growth or mortality. After endrin was withdrawn from the diet, it rapidly disappeared and could not be detected after 41 days. In fish exposed to 0.5 μg endrin/liter of water, mortalities began at tissue levels of 0.7 μg endrin/g of wet whole fish and total mortality occurred at levels near 1.0 μg/g.

Journal of the Fisheries Research Board of Canada↗
USGS1980

Sterility method of pest control and its potential role in an integrated sea lamprey ( Petromyzon marinus ) control program

The sterility method of pest control could be an effective tool in the sea lamprey ( Petromyzon marinus ) control program in the Great Lakes. Some of the requirements for its successful application have been met. A field study demonstrated that the release of male sea lampreys, sterilized by the injection of 100 mg/kg of P , P -bis(1-aziridinyl)- N -methylphosphinothioic amide (bisazir), will reduce the number of viable larvae produced. The actual reduction in reproductive success that occurred was directly related to the ratio of sterile to normal males in the population. The technique can be used in many ways in an integrated control program and has considerable potential for the more effective control of the sea lamprey. Eradication is a distinct possibility. Key words : sea lamprey, Petromyzon marinus ; pest control, fish control, sterile-male technique, sterilization, chemosterilants, bisazir, Great Lakes

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1948

The value of certain drugs, especially sulfa drugs, in the treatment of furunculosis in brook trout, Salvelinus fontinalis

Furunculosis of salmonoid fishes is a dread epizootic disease caused by a general infection by Bacterium salmonicida. In this experiment, treatment was tried with sulfonamides and another drug, “furacin” or “2–20–99” (new drug). The four treatments first used were: (1) sulfamerazine, (2) sulfathiazole, and (3) furacin, each administered by being mixed with the food; and (4) furacin added to the water of the troughs. For assignment of treatments, the troughs containing fingerling brook trout, approximately 8 months old and running 30 to the pound, were grouped in four blocks of five troughs–three blocks of fingerlings with furunculosis, and one block of fingerlings of similar age and size but free from this disease. In each block, one trough received no medication. The various treatments were assigned to troughs by random selection. The block of healthy fish was to test for possible serious ill effects from any of the treatments, and was located some distance from the infected fish. Treatments were begun August 30, 1945, and those involving sulfamerazine and sulfathiazole were continued through 25 days. The furacin treatments, less promising than the sulfonamide treatments, were replaced by sulfanilamide and sulfadiazine, each in the food, on the sixteenth day. Furacin in the water was not beneficial but furacin in the food had some helpful effect. Results with sulfanilamide and sulfadiazine were not encouraging. Sulfathiazole seems to have been more beneficial than furacin, but decidedly less effective than sulfamerazine. The improvement with sulfamerazine was impressive. Mortality dropped rapidly within a few days, generally was light after a week, and within 2 weeks almost completely stopped. Through 25 days, the loss was 17 percent, as compared with 50 percent among the infected lots not receiving medication. The data indicate that 8 grams of sulfamerazine per day per 100 pounds of fish is sufficient, and that a considerably lower dose is at least beneficial. Until further information is available, 8 grams of sulfamerazine per day per 100 pounds of fish, to be continued for at least 6 days after mortality stops, is recommended.

Transactions of the American Fisheries Society↗
USGS1952

Movements of yellow perch marked in southern Green Bay, Lake Michigan, in 1950

To obtain information on the post-spawning movements of yellow perch that spawn in southern Green Bay, Lake Michigan, 4,172 fish caught in drop nets were marked by tagging with monel-metal strap tags attached to the right operculum and 24,799 were marked by clipping off the second or membranous dorsal fin. Marking was done during the period from May 3 to 17, 1950, at six main stations, all located in the southern end of Green Bay. The average length of the tagged perch was 7.3 inches and all fell within the range 5.5–14.4 inches. Most (90.9 percent) of the fish were below the minimum legal length of 8.0 inches. The follow-up procedure consisted of informing commercial and sports fishermen of the program and enlisting their cooperation in watching for marked fish; accounts of the investigation were released through newspapers and descriptive posters were distributed. The personnel connected with the investigation examined catches frequently. The large majority (101 or 79.5 percent) of the 127 tagged perch recaptured in the experimental nets during the marking operations were retaken at the tagging station at which they were released. Of the 108 tagged perch captured by commercial fishermen and anglers following the opening of the season on May 20, 96 were taken by drop nets, 6 by gill nets, and 6 by hook and line. The mean lengths for the three groups were 7.7, 7.1, and 9.25 inches, respectively. All recoveries were made in the Wisconsin waters of Green Bay. Most of the “open-season” recoveries (86 fish; 79.6 percent) were made during the period May 20-May 31. Recaptures during subsequent months were: June–14; July–7; August–none; September–1. Of the 86 perch recaptured May 20–31, 70 were retaken inside and 16 outside the tagging area. The majority (14 of 22) of those recovered after May 31 were retaken outside the tagging area. The average length of the 20 tagged yellow perch recaptured by drop nets (data restricted to fish from a single type of net to avoid bias from gear selectivity) outside the tagging area (8.42 inches) was 0.96 inch greater than the mean length (7.46 inches) of the 76 fish retaken inside the area. This statistically highly significant difference lends support to the belief of commercial fishermen that the larger of the yellow perch that spawn in southern Green Bay move out soon after spawning. The percentage of recapture of tagged perch increased sharply with increase in the size of the fish. Not one of 169 tagged fish less than 6.5 inches long was recovered. The rates of recapture at greater lengths were: 6.5 to 8.9 inches–2.5 percent; 9.0 to 9.9 inches–11.4 percent; 10.0 to 14.4 inches–16.7 percent. Among the several factors suggested in explanation of this relationship, the most important appear to be the lesser ability of the smaller fish to survive the rigors of handling and tagging, greater loss of tags from the smaller fish, and the greater likelihood of overlooking the smaller of the tagged fish in the sorting of the catch. The factors just mentioned and the lack of knowledge of the efficiency of measures taken to obtain records of recoveries preclude the 2.6-percent return of all tagged fish from being accepted as an approximation of the rate of recapture. Neither should the 6.6-percent return of tagged fish of legal size (8 inches and longer) be taken as an estimate of the rate of exploitation. Although 465 fin-clipped perch were recovered in the experimental nets during the marking operations, only 68 of 24,799 fish so marked were recovered after the fishing season opened. All but one of these 68 were retaken near the point of marking. The difficulty of detecting a perch with a missing membranous dorsal is believed to be a major cause of the poor returns from fin-clipped fish. These investigations have demonstrated that for studying migration of yellow perch, tagging is superior to fin-clipping as a method of marking. The technique of the tagging, however, needs to be improved, and better means must be found to trace tagged fish of small size. Furthermore certain small regions in the bay not at present open to commercial fishing must be explored in order to obtain more comprehensive information as to migration.

Transactions of the American Fisheries Society↗
USGS1989

Distribution and migration of adult striped bass in Lake Whitney, Texas

Thirty adult (3.2–8.6 kg) striped bass Morone saxatilis were tagged with ultrasonic transmitters and tracked for up to 475 d in 9,510‐hectare Lake Whitney, a Texas reservoir, to determine seasonal distribution, migration patterns, and water temperatures occupied. Striped bass distribution in summer was limited to an area near the dam, where they survived temperatures as high as 29.0°C. Tagged fish generally were found in the coolest water available (27.0–29.0°C) that contained adequate dissolved oxygen (>4.0 mg/L) in summer and occupied the warmest water (7.4–8.8°C) in winter. For the rest of the year, the fish were distributed throughout available water temperatures. Beginning in autumn, most striped bass moved up the reservoir to and into the main tributaries and remained there until spring, when they returned to the main reservoir. No spawning run up main tributaries was observed in either of the two study years, possibly due to low inflows. Individual fish displayed a preference for certain areas to which they returned yearly.

Texas↗
USGS1999

Movements of adult chinook salmon during spawning migration in a metals-contaminated system, Coeur d'Alene River, Idaho

Spawning migration of adult male chinook salmon Oncorhynchus tshawytscha was monitored by radio telemetry to determine their response to the presence of metals contamination in the South Fork of the Coeur d'Alene River, Idaho. The North Fork of the Coeur d'Alene River is relatively free of metals contamination and was used as a control. In all, 45 chinook salmon were transported from their natal stream, Wolf Lodge Creek, tagged with radio transmitters, and released in the Coeur d'Alene River 2 km downstream of the confluence of the South Fork and the North Fork of the Coeur d'Alene River. Fixed telemetry receivers were used to monitor the upstream movement of the tagged chinook salmon through the confluence area for 3 weeks after release. During this period, general water quality and metals concentrations were monitored in the study area. Of the 23 chinook salmon observed to move upstream from the release site and through the confluence area, the majority (16 fish, 70%) moved up the North Fork, and only 7 fish (30%) moved up the South Fork, where greater metals concentrations were observed. Our results agree with laboratory findings and suggest that natural fish populations will avoid tributaries with high metals contamination.

Transactions of the American Fisheries Society↗