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At least 19 recordsLinked to original sources
USGS2011

The fundamental thermal niche of adult landlocked striped bass

Researchers have described the temperatures selected by landlocked striped bass Morone saxatilis in different locales throughout the USA. However, seasonally low concentrations of dissolved oxygen (DO) in many systems prevented striped bass from using the cool waters (<22??C) they may have preferred. In Melton Hill Reservoir, a 92-km-long impoundment on the Clinch River in east Tennessee, 15 adult striped bass were tagged with temperature-sensing radio tags and tracked for an average of 418 d in 1999-2000. Cold, hypolimnetic discharges from an upstream dam and heated discharge from a steam-generating electric facility near the midpoint of this run-of-the-river reservoir provided a broad range of temperatures in most seasons, and hypoxic habitats were uncommon even during stratification. The mean temperature occupied by striped bass varied seasonally (repeated-measures analysis of variance, P < 0.0001) and was highest in summer (17.5??C), intermediate in spring and fall (15.4-16.9??C), and lowest in winter (13.0??C). The mean and modal temperatures occupied during the growing season (May-October 1999) were 17.5??C and 19.0??C, respectively; 30% of the observations were between 9??C and 15??C. These data indicate that the fundamental thermal niche of adult landlocked striped bass may be lower than literature estimates. These results also represent the first unbiased field estimates of the influence of season on the thermal ecology of adult striped bass. The thermal characteristics of habitats considered optimal in habitat suitability index models for adult landlocked striped bass (i.e., 18-24??C) should be revised to include cooler waters. ?? Copyright by the American Fisheries Society 2005.

Transactions of the American Fisheries Society↗
USGS2011

Regulation of an unexploited brown trout population in Spruce Creek, Pennsylvania

The purpose of this paper is to describe the annual variations in the density of an unexploited population of lotic brown trout Salmo trutta that has been censused annually for 19 years and to explore the importance of density-independent and density-dependent processes in regulating population size. Brown trout density and indices of stream discharge and water temperature were related to annual variations in natural mortality, recruitment, and growth. Annual mortality of age-1 and older (age-1+) brown trout ranged from 0.30 to 0.75 and was best explained by discharge during spring and by brown trout density. Recruitment to age 1 varied fivefold. Density of age-1 brown trout was inversely related to spawner density and positively related to discharge during the fall spawning period. The median length of age-1 brown trout was positively related to discharge during summer and fall. Relative weight was inversely related to the density of age-2+ brown trout. The interactive effects of discharge and brown trout density accounted for most of the annual variation in mortality, recruitment, and growth during the first year of life. Annual trends in the abundance of age-1+ brown trout were largely dictated by natural mortality. ?? Copyright by the American Fisheries Society 2006.

Transactions of the American Fisheries Society↗
USGS2011

Approximate sample sizes required to estimate length distributions

The sample sizes required to estimate fish length were determined by bootstrapping from reference length distributions. Depending on population characteristics and species-specific maximum lengths, 1-cm length-frequency histograms required 375-1,200 fish to estimate within 10% with 80% confidence, 2.5-cm histograms required 150-425 fish, proportional stock density required 75-140 fish, and mean length required 75-160 fish. In general, smaller species, smaller populations, populations with higher mortality, and simpler length statistics required fewer samples. Indices that require low sample sizes may be suitable for monitoring population status, and when large changes in length are evident, additional sampling effort may be allocated to more precisely define length status with more informative estimators. ?? Copyright by the American Fisheries Society 2007.

Transactions of the American Fisheries Society↗
USGS1998

Consequences of cannibalism and competition for food in a smallmouth bass population: An individual-based modeling study

We used an individual-based modeling approach to study the consequences of cannibalism and competition for food in a freshwater fish population. We simulated the daily foraging, growth, and survival of the age-0 fish and older juvenile individuals of a sample population to reconstruct patterns of density dependence in the age-0 fish during the growth season. Cannibalism occurs as a part of the foraging process. For age-0 fish, older juvenile fish are both potential cannibals and competitors of food. We found that competition and cannibalism produced intraclass and interclass density dependence. Our modeling results suggested the following. (1) With low density of juvenile fish and weak interclass interactions, the age-0 fish recruitment shows a Beverton-Holt type of density dependence. (2) With high density of juvenile fish and strong interclass interactions, the age-0 fish recruitment shows a Ricker type of density dependence, and overcompensation occurs. (3) Interclass competition of food is responsible for much of the overcompensation. (4) Cannibalism intensifies the changes in the recruitment that are brought about by competition. Cannibalism can (a) generally reduce the recruitment, (b) particularly reduce the maximum level of recruitment, (c) cause overcompensation to occur at lower densities, and (d) produce a stronger overcompensation. (5) Growth is also a function of density. Cannibalism generally improves average growth of cannibals. (6) Variation in the lengths of age-0 fish increases with density and with a decreased average growth. These results imply that cannibalism and competition for food could strongly affect recruitment dynamics. Our model also showed that the rate of cannibalism either could be fairly even through the whole season or could vary dramatically. The individual-based modeling approach can help ecologists understand the mechanistic connection between daily behavioral and physiological processes operating at the level of individual organisms and seasonal patterns of population structure and dynamics. ?? Copyright by the American Fisheries Society 1998.

Transactions of the American Fisheries Society↗
USGS2011

Effects of turbidity, light level, and cover on predation of white sturgeon larvae by prickly sculpins

White sturgeon Acipenser transmontanus occur in rivers of the western United States and southwestern Canada, but some populations are in decline because of recruitment failure. Many river systems in this area have been altered as a result of development that has caused major environmental changes. Our goal was to examine how three changes - lower turbidity levels, higher light levels, and altered substrates - might affect predation by prickly sculpin Cottus asper on white sturgeon larvae. We experimentally investigated predation at various turbidity levels and found that significantly more white sturgeon yolk sac larvae were eaten at lower turbidity levels. The effects of light level (1-4 and 7-15 1x), the presence or absence of rocks as cover, and prey size (14-17 mm and 20-24 mm total length) on the outcome of predator-prey interactions were also examined. Significantly fewer white sturgeon were eaten during trials that combined the lowest light level, cover, and the smallest larvae. Our results suggest that altered river conditions caused by impoundment and other factors have increased predation on white sturgeon larvae. ?? Copyright by the American Fisheries Society 2005.

Transactions of the American Fisheries Society↗
USGS2011

Development of a bioenergetics model for humpback chub and evaluation of water temperature changes in the Grand Canyon, Colorado River

The construction of Glen Canyon Dam above the Grand Canyon (Arizona) has reduced the water temperature in the Colorado River and altered the growth rate and feeding patterns of the federally endangered humpback chub Gila cypha. A bioenergetics model for humpback chub was developed and used to examine how warmer water temperatures in the lower Colorado River (achieved through a temperature control device [TCD] at Glen Canyon Dam) might influence their growth rate and food requirements. Parameter values for humpback chub were developed by Monte Carlo filtering and fitting to laboratory growth. Parameter bounds were established from the literature for Gila species, random parameter sets were selected within these bounds, and the growth of modeled humpback chub was compared with criteria from a laboratory growth experiment at 24??C. This method of parameter estimation could be applied to other imperiled fishes where physiological studies are impractical. Final parameter values were corroborated by comparison with the growth rates of humpback chub from independent field and laboratory studies. Simulations indicated that increasing water temperatures from approximately 9??C to 16??C during summer and fall, the change expected from the TCD, may have a minimal effect on humpback chub growth rate unless food availability also increases with temperature. To evaluate the effects of increased temperatures on humpback chub in the lower Colorado River, it will be essential to monitor their growth rate, the invertebrate community, and the predators of humpback chub, which are also influenced by temperature changes. Bioenergetics models for humpback chub and their predators should be helpful tools for identifying potential scenarios and evaluating the complex interactions resulting from a TCD. ?? Copyright by the American Fisheries Society 2005.

Transactions of the American Fisheries Society↗
USGS2011

Population characteristics and assessment of overfishing for an exploited paddlefish population in the lower Tennessee River

Paddlefish Polyodon spathula (n = 576) were collected from Kentucky Lake, Kentucky-Tennessee, with experimental gill nets in 2003-2004 to assess population characteristics and the potential for commercial overfishing. Additional data were collected from 1,039 paddlefish caught by commercial gillnetters in this impoundment. Since the most recent study in 1991, size and age structure have been reduced and annual mortality has tripled. In the 1991 study, 37% of the fish collected were older than the maximum age we observed (age 11), and in 2003 annual mortality for paddlefish age 7 and older was high (A = 68%). Natural mortality is presumably low (<10%) for paddlefish; therefore, exploitation in recent years is high. Estimates of total annual mortality were negatively related to river discharge in the years preceding each estimate. The number of paddlefish harvested since 1999 was also negatively related to river discharge because gill nets cannot be easily deployed when discharge exceeds approximately 850 m3/s. Large females spawn annually because all females longer than 1,034 mm eye-fork length (EFL) were gravid. No mature females were protected by the current 864-mm minimum EFL limit. At a low natural mortality rate, higher size limits when exploitation was high (40-70%) increased simulated flesh yields by 10-20%. Even at low levels of exploitation (21%), spawning potential ratios (SPRs) under the current 864-mm minimum EFL size limit fell below 20%. If the size limit was raised to 1,016 mm EFL, the population could withstand up to 62% exploitation before the SPR falls below 20%. An analysis of annual mortality caps indicated that the best way to increase the average size of harvested fish is to increase the minimum size limit. Recruitment overfishing probably occurs during drought years; however, variation in river discharge has prevented the population from being exploited at unsustainable rates in the past. ?? Copyright by the American Fisheries Society 2005.

Transactions of the American Fisheries Society↗
USGS2011

Influence of landscape-scale factors in limiting brook trout populations in Pennsylvania streams

Landscapes influence the capacity of streams to produce trout through their effect on water chemistry and other factors at the reach scale. Trout abundance also fluctuates over time; thus, to thoroughly understand how spatial factors at landscape scales affect trout populations, one must assess the changes in populations over time to provide a context for interpreting the importance of spatial factors. We used data from the Pennsylvania Fish and Boat Commission's fisheries management database to investigate spatial factors that affect the capacity of streams to support brook trout Salvelinus fontinalis and to provide models useful for their management. We assessed the relative importance of spatial and temporal variation by calculating variance components and comparing relative standard errors for spatial and temporal variation. We used binary logistic regression to predict the presence of harvestable-length brook trout and multiple linear regression to assess the mechanistic links between landscapes and trout populations and to predict population density. The variance in trout density among streams was equal to or greater than the temporal variation for several streams, indicating that differences among sites affect population density. Logistic regression models correctly predicted the absence of harvestable-length brook trout in 60% of validation samples. The r 2-value for the linear regression model predicting density was 0.3, indicating low predictive ability. Both logistic and linear regression models supported buffering capacity against acid episodes as an important mechanistic link between landscapes and trout populations. Although our models fail to predict trout densities precisely, their success at elucidating the mechanistic links between landscapes and trout populations, in concert with the importance of spatial variation, increases our understanding of factors affecting brook trout abundance and will help managers and private groups to protect and enhance populations of wild brook trout. ?? Copyright by the American Fisheries Society 2006.

Transactions of the American Fisheries Society↗
USGS2011

Stream pH as an abiotic gradient influencing distributions of trout in Pennsylvania streams

Elevation and stream slope are abiotic gradients that limit upstream distributions of brook trout Salvelinus fontinalis and brown trout Salmo trutta in streams. We sought to determine whether another abiotic gradient, base-flow pH, may also affect distributions of these two species in eastern North America streams. We used historical data from the Pennsylvania Fish and Boat Commission's fisheries management database to explore the effects of reach elevation, slope, and base-flow pH on distributional limits to brook trout and brown trout in Pennsylvania streams in the Appalachian Plateaus and Ridge and Valley physiographic provinces. Discriminant function analysis (DFA) was used to calculate a canonical axis that separated allopatric brook trout populations from allopatric brown trout populations and allowed us to assess which of the three independent variables were important gradients along which communities graded from allopatric brook trout to allopatric brown trout. Canonical structure coefficients from DFA indicated that in both physiographic provinces, stream base-flow pH and slope were important factors in distributional limits; elevation was also an important factor in the Ridge and Valley Province but not the Appalachian Plateaus Province. Graphs of each variable against the proportion of brook trout in a community also identified apparent zones of allopatry for both species on the basis of pH and stream slope. We hypothesize that pH-mediated interspecific competition that favors brook trout in competition with brown trout at lower pH is the most plausible mechanism for segregation of these two species along pH gradients. Our discovery that trout distributions in Pennsylvania are related to stream base-flow pH has important implications for brook trout conservation in acidified regions. Carefully designed laboratory and field studies will be required to test our hypothesis and elucidate the mechanisms responsible for the partitioning of brook trout and brown trout along pH gradients. ?? Copyright by the American Fisheries Society 2005.

Transactions of the American Fisheries Society↗
USGS2011

Spawning distribution of sockeye salmon in a glacially influenced watershed: The importance of glacial habitats

The spawning distribution of sockeye salmon Oncorhynchus nerka was compared between clear and glacially turbid habitats in Lake Clark, Alaska, with the use of radiotelemetry. Tracking of 241 adult sockeye salmon to 27 spawning locations revealed both essential habitats and the relationship between spawn timing and seasonal turbidity cycles. Sixty-six percent of radio-tagged sockeye salmon spawned in turbid waters (???5 nephelometric turbidity units) where visual observation was difficult. Spawning in turbid habitats coincided with seasonal temperature declines and associated declines in turbidity and suspended sediment concentration. Because spawn timing is heritable and influenced by temperature, the observed behavior suggests an adaptive response to glacier-fed habitats, as it would reduce embryonic exposure to the adverse effects of fine sediments. ?? Copyright by the American Fisheries Society 2007.

Transactions of the American Fisheries Society↗
USGS2011

Previously undocumented two-year freshwater residency of juvenile coho salmon in Prairie Creek, California

Over 2,000 juvenile coho salmon Oncorhynchus kisutch were tagged with passive integrated transponder (PIT) tags during the fall of 1998 and 1999 in Prairie Creek, California, as part of a study on individual winter growth rates and movement of juvenile coho salmon. During this study, age-2 out-migrants were incidentally observed. Previously, it had been generally assumed that all juvenile coho salmon in northern California streams spend only 1 year in freshwater before out-migrating at age 1 and that a 2-year freshwater life history pattern was found only in the more northerly portions of the species' range. Subsequently, scale analysis of PIT-tagged fish recaptured during spring out-migration was used as a basis for estimating the proportion of out-migrants displaying a 1- or 2-year freshwater residency life history. Twenty-eight percent (28%) of out-migrants captured in spring 2000 displayed a 2-year freshwater residency life history, apparently related to low winter growth rates documented in related research in the study stream. ?? Copyright by the American Fisheries Society 2007.

Transactions of the American Fisheries Society↗
USGS2011

Phylogenetic and ecological characteristics associated with thiaminase activity in Laurentian Great Lakes fishes

Thiamine deficiency complex (TDC) causes mortality and sublethal effects in Great Lakes salmonines and results from low concentrations of egg thiamine that are thought to be caused by thiaminolytic enzymes (i.e., thiaminase) present in the diet. This complex has the potential to undermine efforts to restore lake trout Salvelinus namaycush and severely restrict salmonid production in the Great Lakes. Although thiaminase has been found in a variety of Great Lakes fishes, the ultimate source of thiaminase in Great Lakes fishes is currently unknown. We used logistic regression analysis to investigate relationships between thiaminase activity and phylogenetic or ecological characteristics of 39 Great Lakes fish species. The taxonomically more ancestral species were more likely to show thiaminase activity than the more derived species. Species that feed at lower trophic levels and occupy benthic habitats also appeared to be more likely to show thiaminase activity; these variables were correlated with taxonomy, which was the most important predictor of thiaminase activity. Further analyses of the relationship between quantitative measures of thiaminase activity and ecological characteristics of Great Lakes fish species would provide greater insight into potential sources and pathways of thiaminase in Great Lakes food webs. ?? Copyright by the American Fisheries Society 2008.

Transactions of the American Fisheries Society↗
USGS2011

A simple model for predicting survival of angler-caught and released largemouth bass

We conducted a controlled experiment in the laboratory to assess the influence of anatomical hooking location and water temperature on survival of angler-caught and released largemouth bass Micropterus salmoides. Survival was 98% (58 of 59 fish) among fish that were hand-hooked within the oral cavity (including the gills), whereas survival was 66% (33 of 50 fish) among fish that were hand-hooked in the esophagus. Survival of hooked fish was not significantly influenced by water temperature (7-27??C) or the hooking location X water temperature interaction. We combined our results with prior research to develop a predictive model of largemouth bass survival, which was 98.3% (SD = 1.87%) for fish hooked in the oral cavity and 55.0% (SD = 9.70%) for fish hooked in the esophagus. The model is valid for water temperatures ranging from 7??C to 27??C and allows one to estimate, with known precision, the survival of angler-caught and released largemouth bass without the need for controlled studies or for holding fish in pens or cages to assess delayed mortality. ?? Copyright by the American Fisheries Society 2008.

Transactions of the American Fisheries Society↗
USGS2011

Seasonal distribution, aggregation, and habitat selection of common carp in Clear Lake, Iowa

The common carp Cyprinus carpio is widely distributed and frequently considered a nuisance species outside its native range. Common carp are abundant in Clear Lake, Iowa, where their presence is both a symptom of degradation and an impediment to improving water quality and the sport fishery. We used radiotelemetry to quantify seasonal distribution, aggregation, and habitat selection of adult and subadult common carp in Clear Lake during 2005-2006 in an effort to guide future control strategies. Over a 22-month period, we recorded 1,951 locations of 54 adults and 60 subadults implanted with radio transmitters. Adults demonstrated a clear tendency to aggregate in an offshore area during the late fall and winter and in shallow, vegetated areas before and during spring spawning. Late-fall and winter aggregations were estimated to include a larger percentage of the tracked adults than spring aggregations. Subadults aggregated in shallow, vegetated areas during the spring and early summer. Our study, when considered in combination with previous research, suggests repeatable patterns of distribution, aggregation, and habitat selection that should facilitate common carp reduction programs in Clear Lake and similar systems. ?? Copyright by the American Fisheries Society 2008.

Transactions of the American Fisheries Society↗
USGS2011

Boat electrofishing relative to anode arrangement

We assessed the effect of boom (i.e., anode) arrangement (a single boom and double booms spaced 1.3, 1.9, and 3.2 m apart) on the characteristics of the electric field formed ahead of an electrofishing boat as well as on fish catch. Anode arrangement affected the lengthwise and crosswise characteristics of the field. As a general rule, rearranging the anodes from a single boom located centrally to a double-boom system with broadly separated anodes shifted the strength of the field outward (away from the center) and forward (away from the boat). The highest voltage gradients occurred when the anodes had the greatest separation. Catch rates varied by boom arrangement, increasing as boom separation increased. Differences in species and length selectivity with respect to boom arrangement were minor. We suggest that the double-boom arrangement with the booms placed about 1.9 m apart (but no more than about 2.5 m) is suitable for most electrofishing applications. ?? Copyright by the American Fisheries Society 2008.

Transactions of the American Fisheries Society↗
USGS1947

Mortality of smelt, Osmerus mordax (Mitchill), in Lakes Huron and Michigan during the fall and winter of 1942-1943

The mortality that nearly exterminated the huge stocks of smelt in Lakes Huron and Michigan during the fall and winter of 1942&ndash;1943 appears to have originated in central Lake Huron in the Saginaw Bay area in late September or early October 1942. The mortality spread rapidly northward reaching the Drummond Island area about the latter part of October and the St. Ignace region of the Straits of Mackinac near the end of the month. In the latter part of October smelt died also in the Canadian waters of Lake Huron including North Channel and Georgian Bay but exact details as to time and course are lacking. There is some evidence that the epidemic had not reached the Ontario shore of central Lake Huron by late May 1943. Spreading through northern Lake Michigan the mortality had penetrated as far south as Grand Traverse Bay by November 19 and as far west as Point Aux Barques, Michigan, by November 26, 1942. Smelt were reported to be dying in Lake Charlevoix, Michigan, in early February 1943, and in Green Bay toward the middle of that month. The mortality did not reach Crystal Lake where in contrast to Lake Charlevoix a dam barred the passage of fish from Lake Michigan. At the time of the 1943 spring spawning run (April) only a few scattered survivors remained from the vast populations. After consideration of possible causes, it was concluded that the mortality could be explained only as resulting from a communicable disease (bacteria or virus). This explanation alone is in harmony with the following facts: the mortality was progressive, spreading from one area into adjacent areas over a period of at least 4 1/2 months and under a great diversity of habitat conditions; only smelt were affected but within the species death overtook fish of all sizes from 2 inches on and all ages of both sexes, mature and immature; the mortality penetrated Lake Charlevoix where the passage of fish to and from Lake Michigan was possible but did not reach Crystal Lake where the passage from Lake Michigan was barred by a dam; the epidemic did not reach other inland lakes where free and easy access from the Great Lakes was impossible nor did it extend to Lakes Superior, Erie, and Ontario. Considered at first as a nuisance and a threat to the native fishes of the Great Lakes, the smelt ultimately became a fish of primary importance to commercial fishermen, sportsmen, and others. In Green Bay, the center of the commercial fishery, smelt became the dominant commercial species, yielding more than 4 million pounds in some years. Almost all of the commercial production was from nets set under the ice. The take by amateurs and others who dipped smelt from streams during the spawning run was even greater, amounting to as much as 5 1/2 million pounds in a single year in the State of Michigan alone (the yield in Wisconsin may have been nearly as great). The mortality of smelt was a severe blow to the nation's war-time food-production program. It is estimated that in 1943, in which year elaborate preparations had been made for the efficient utilization of the spawning-run production, the mortality reduced the output of smelt by about 13 million pounds. The total loss through the present (1946) season can be set in the neighborhood of 50 million pounds. The first indication of a recovery of the smelt came in 1945 when a small amount was produced commercially in Green Bay and numerous light runs occurred in streams tributary to Lakes Huron and Michigan. The general level of abundance in 1945, however, is believed to have been less than 10 per cent of that of &ldquo;pre-mortality&rdquo; years. Such information as is available for 1946 suggests considerable further improvement in this year. Given good survival of young, it is anticipated that a large rise in the abundance of smelt can occur in 1947 and that by 1948 or 1949 the size of the populations should no longer be influenced by the number of spawners available in preceding years. The smelt from the Escanaba area of Green Bay were without exception significantly longer and heavier in 1944 and 1945 than were fish of corresponding age captured in the same region in 1941. Furthermore, three of four comparisons indicated significantly greater size in 1945 than in 1944. This improvement in growth rate is believed to have been associated with the reduction in the smelt population brought about by the 1942&ndash;1943 mortality.

Transactions of the American Fisheries Society↗