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Results for “Transactions of American Fisheries Society”

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At least 577 records · Page 32Linked to original sources
USGS1982

Growth and condition of bluegills in Wisconsin lakes: Effects of population density and lake pH

Growth and condition of bluegills Lepomis macrochirus from five acidic lakes (pH 5.1–6.0) and six circumueutral lakes (pH 6.7–7.5) in northern Wisconsin were compared. Although mean condition factors and mean back‐calculated total lengths at ages 1 to 4 varied significantly among lakes, the differences were not related to lake pH. Rather, the ranks of mean condition factors and back‐calculated lengths at ages 2, 3, and 4 were negatively correlated with relative density of bluegills among the lakes. Because of the dominating effect of density, growth rates and condition factors are not useful as indicators of chronic, pH‐related stress on bluegill populations.

Transactions of the American Fisheries Society↗
USGS1983

Distribution of larval fishes related to potential navigation impacts on the upper Mississippi River, pool 7

Ichthyoplankton samples were collected twice monthly during spring and summer 1981 from a variety of habitats in Navigation Pool 7 of the upper Mississippi River. Larval‐fish distributions in the pool and variations in those distributions were analyzed relative to potential impacts of increased commercial navigation. Although as many as 66 species of adults have been found in the area (33 considered common), only 17 taxa were identified from our collections. In April and May, most larvae were collected in main‐channel and main‐channel‐border areas next to major expanses of shallow backwaters. White bass Morone chrysops, yellow perch Perca flavescens, and crappies Pomoxis spp. were predominant. Numerous catostomids also were taken. In June and July, most larvae were taken in the lower pool. Freshwater drum Aplodinotus grunniens and gizzard shad Dorosoma cepedianum predominated in these samples, which also included many cyprinids and centrarchids. Diel patterns of abundance varied with species and sampling location. Freshwater drums were more abundant near the surface at midnight than during the day. Common carp Cyprinus carpio were most abundant in collections at dusk, whereas all other cyprinids were most abundant at dusk and dawn. Numbers of gizzard shad also increased slightly at dusk. Total numbers of larvae collected were greatest at dusk in main‐channel and main‐channel‐border samples; backwater areas produced the greatest catches at midnight and dawn. Seasonal, spatial, diel, and species‐specific variations in larval fish abundances significantly influenced the proportion of the community potentially vulnerable to increased boat traffic through Pool 7.

upper Mississippi River↗
USGS1983

Changes in phototaxis during early development of walleye

Phototaxis of walleyes Stizostedion vitreum vitreum was examined during the first 11 weeks of larva and juvenile development. Fish were subjected to six light intensities ranging from 2 to 34 lux, plus 7,800 lux as an extreme. The number of fish positioned in each light intensity was used to determine the phototactic response. Larvae and juveniles 1 to 8 weeks old (9 to 32 mm total length) were attracted to the highest light intensity (7,800 lux), and juveniles older than 8 weeks (32 to 40 mm long) aggregated at the lowest intensities (2 and 4 lux). The change from positive to negative phototaxis was more closely related to fish size than to age.

Transactions of the American Fisheries Society↗
USGS1983

Feminization of channel catfish by oral administration of steroid sex hormones

Oral administration of 17‐β‐estradiol or 17‐α‐ethynyltestosterone to sexually undifferentiated channel catfish Ictaturus punctatus during the first 21 days after yolk‐sac absorption resulted in the production of 100% females. The androgen was effective at doses of 6 to 600 μg/g of feed, but not at 0.6 μg/g.

Transactions of the American Fisheries Society↗
USGS1983

Rapid method for measuring rotenone in water at piscicidal concentrations

A high‐performance liquid chromatography (HPLC) procedure that is rapid, specific, and sensitive (limit of detection <0.005 mg/liter) was developed for monitoring application and degradation rates of rotenone. For analysis, a water sample is buffered to pH 5 and injected through a Sep Pak(R) C 18 disposable cartridge. The cartridge adsorbs and retains the rotenone which then can be eluted quantitatively from the cartridge with a small volume of methanol. This step effectively concentrates the sample and provides sample cleanup. The methanol extract is analyzed directly by HPLC on an MCH 10 reverse‐phase column; methanol: Water (75:25, volume : Volume) is the mobile phase and flow rate is 1.5 ml/minute. The rotenone is detected by ultraviolet spectrophotometry at a wavelength of 295 nm.

Transactions of the American Fisheries Society↗
USGS1983

Reproduction by the endangered cui-ui in the lower Truckee River

Adult spawning behavior and emigration of larvae of the endangered cui-ui Chasmistes cujus were studied in a natural side channel of the lower Truckee River. External radio-tags placed on eight apparently did not affect spawning behavior. Cui-uis spawned in clusters of two to seven fish; usually a single female was flanked by two males. Each spawning act lasted 3–6 seconds, and individual fish spawned numerous times. The most active tagged male and female spawned at least 294 times and 114 times, respectively. Individual females broadcast eggs over an area of up to 50 m 2 . Males spawned over a 4–5-day period, and females over 2.5–4 days. Most spawning occurred at night in water depths ranging from 9 to 43 cm, water velocities ranging from 23 to 87 cm/second, and temperatures of 12–17 C. The preferred spawning substrate was gravel. Peak emergence and out-migration of cui-ui larvae occurred 14 days after peak spawning.

California, Nevada↗
USGS1983

Dietary requirements for essential branched-chain amino acids by lake trout

In a 12‐week growth study of the dietary requirements of young lake trout Salvelinus namaycush for essential branched‐chain amino acids, the leucine requirement was between 2.74 and 3.66%, and the isoleucine requirement between 1.54 and 2.06%, of dietary protein (as‐fed basis). These ranges are substantially lower than those published and widely used in formulation of salmonid feeds. On the basis of both growth criteria and concentration of free amino acids in blood plasma, the valine requirement was within the range of 1.77 to 2.23% of dietary protein. The upper value of this range is substantially lower than the requirement reported for chinook salmon Oncorhynchus tshawytscha. Plasma valine concentrations in lake trout responded to dietary supplements of valine above the requirement level; the concentrations increased sharply once the requirement was exceeded. This finding is similar to observations recorded in other animals.

Transactions of the American Fisheries Society↗
USGS1983

Resistance of salmonids to Aeromonas salmonicida: Relation between agglutinins and neutralizing activities

Serum of furunculosis‐resistant rainbow trout Salmo gairdneri, when injected into brook trout Salvelinus fontinalis, increased resistance of the brook trout to virulent challenges of Aeromonas salmonicida, the furunculosis pathogen. Serum from susceptible Atlantic salmon Salmo salar did not confer passive resistance on brook trout although natural agglutinin titers in Atlantic salmon serum were equal to those in rainbow trout. Further analyses indicated that rainbow trout serum neutralized toxic components produced by A. salmonicida, but that Atlantic salmon serum did not. When 11 strains of rainbow trout were challenged with 10 9 virulent cells of A. salmonicida, a range of mortality from 0 to 83% resulted. Although no correlation was observed between the natural serum agglutinin level of a particular strain and its relative resistance to experimental pathogen challenge, an inverse relation was apparent between cytotoxic serum‐neutralization activity and resistance to furunculosis.

Transactions of the American Fisheries Society↗
USGS1984

Biotic and abiotic influences on corticosteroid hormone rhythms in channel catfish

Plasma‐corticosteroid concentrations in resting channel catfish Ictalurus punctatus held at 21 C varied only slightly during a 24‐hour period; further, increases in hormone concentrations induced by confinement stress were independent of time of day and photoperiod. Temperature strongly affected both resting corticosteroid concentrations and the dynamics of hormone secretion when fish were stressed. Resting concentrations were greatest in fish acclimated to 5 and 10 C (25–29 ng/ml), sharply lower in fish held at 15, 20, or 21 C (5–9 ng/ml), and intermediate in fish maintained at 25, 30, or 35 C (12–13 ng/ml). Hormone concentrations increased when fish were stressed by confinement. Corticosteroid concentrations hardly changed in fish held at 5 or 10 C, but increased markedly in fish at higher temperatures; in addition the response was more delayed at the lower temperatures.

Transactions of the American Fisheries Society↗
USGS1984

Chronobiologic approach to aquaculture

Diel and seasonal changes in the environment directly or indirectly control many biological functions. Chronobiology, the study of biological functions in relation to time of day, time of year, lunar phases, and other consistent cues, could have important applications in aquaculture. Physiological conditions that vary seasonally include feeding time, tolerance of fish to stress, the state of gonad development, lipid and water content of muscle tissue, and the dress‐out weight of food fish. The quality of cultured fish may vary with the time of day when fish are fed, seined, graded, treated with therapeutic chemicals, injected with hormones, or physically disturbed. Efficiency of production and quality of aquacultural products might be improved if the activities of fish husbandry were timed to coincide with the biological rhythms of fish.

Transactions of the American Fisheries Society↗
USGS1984

Bias-elimination in fish population models with stochastic variation in survival of the young

The addition of random variation in survival to a single prereproductive age class in a Leslie matrix population model can alter population growth in the modeled system. Methods are presented to characterize the stochastic variation in survival and to determine a correction factor that, when included in the model, will eliminate the propensity for the modeled population to systematically deviate from the initial conditions. This ability is important for applications of fish population models that seek to evaluate probability distributions of population trends that are associated with stochastic variations in survival, and to forecast the effects of changes in fishing mortality rates in fluctuating environments.

Transactions of the American Fisheries Society↗
USGS1985

Toxic materials, fishing, and environmental variation: Simulated effects on striped bass population trends

Decreased survival of larval striped bass Morone saxatilis resulting from toxic chemicals in the environment and decreased survival of adults caused by fishing both are suspected as agents contributing to the decline in the Chesapeake Bay stock since the mid‐1970s. The relative power of each type of mortality to cause population declines was evaluated with simulation techniques. Equivalent levels of added mortality induced qualitatively identical and quantitatively similar trends in population simulations for all conditions examined except if strong density‐dependent mortality preceded the contaminant toxicity. In this case the contaminant effect caused a greater reduction in yield, but the population did not tend toward extinction. The results indicate that the observed downward trend in the Chesapeake Bay population can be halted or reversed by a reduction in fishing mortality, even if contaminant toxicity is the proximate cause for the decline.

Maryland↗
USGS1985

Use of otoliths to determine age and growth of largemouth bass in Florida

The annual formation of otolith annuli was validated through age 5 for Florida largemouth bass Micropterus salmoides floridanus. Sectioned otoliths (sagittae) gave more reliable ages than whole otoliths. Beginning at age 2, at least one annulus was obscure in some whole‐otolith mounts, a problem that worsened with fish age. By age 5, over 20% of the whole otoliths gave under‐estimates of true age; otoliths producing these errors came from fish with slower than average growth rates. Sectioned otoliths gave poorer regressions (lower coefficients of determination) of otolith radius on body length than intact structures because the sectioning plane varied slightly among otoliths. Nevertheless, back calculations of fish size and growth from sectioned and correctly aged whole otoliths were equally accurate. Otolith sectioning is the procedure of choice for age‐and‐growth analysis of Florida largemouth bass. Whole otoliths, however, require much less time for analysis than sectioned ones and may be used for rapidly growing fish and fish known to be age 3 or younger.

Florida↗
USGS1985

Lake trout reproductive behavior: influence of chemosensory cues from young-of-the-year by-products

Chemosensory cues, particularly those emanating from substrate areas occupied by previously hatched young, may play an important role in the reproductive behavior of lake trout Salvelinus namaycush. Support for this hypothesis was obtained in laboratory experiments. Adults were placed in a large circular pool with four experimental reefs. Egg membranes and feces obtained from young that had hatched earlier were placed in polyester fiber in screen envelopes and positioned on selected reefs. Females approached and males contacted ('cleaned') the treated reefs but not the untreated reefs. Of 6,858 eggs recovered, 92% were from treated reefs. Some of these eggs had been fertilized and provide the first record of volitional spawning by lake trout under artificial conditions. A second experiment was less definitive, because no spawning occurred, but visual observations and analysis of videotaped behavior sequences showed that, again, adults were attracted more to reefs treated with feces of young of the year than to untreated reefs.

Transactions of the American Fisheries Society↗
USGS1985

Gill lamellar dilations (Telangiectasis) related to sampling techniques

Among fish killed by concussion (a blow to the head), lake trout Salvelinus namaycush readily developed telangiectasis, lamellar edema, and hemorrhagic thymi; Atlantic salmon Salmo salar and rainbow trout Salmo gairdneri developed thymic hemorrhages but few or no gill lesions. This illustrates a potentially overlooked bias that sampling techniques can cause in histologic analyses.

Transactions of the American Fisheries Society↗
USGS1985

Relationship between reported commercial landings and abundance of young striped bass in Chesapeake Bay, Maryland

The ability to predict subsequent landings of striped bass Morone saxatilis from the indices of abundance of juveniles (young of the year) determined annually by the Maryland Department of Natural Resources was evaluated by multiple‐regression techniques. About 57% of the variation in reported landings could be accounted for by the juvenile indices 2, 3, 4, and 5 years prior to the year of the landings for the period 1959–1983. Elimination of the first 4 years of record (1959–1962) increased the R 2 to 0.83. The regressions of reported landings on the indices of ages 2–5 striped bass for the periods 1964–1973 and 1974–1983 indicated that mortality in the fishable stock increased between the two periods. These results support the use of the juvenile indices for monitoring recruitment into the population and as a basis for management decisions.

Maryland↗
USGS1986

Dynamics of alewives in Lake Ontario following a mass mortality

The U.S. Fish and Wildlife Service and the New York Department of Environmental Conservation assessed the population of alewives Alosa pseudoharengus in U.S. waters of Lake Ontario during 1976–1982 with bottom trawls. Alewives were abundant in 1976 but a die-off greatly reduced their numbers during the winter of 1976–1977. The population quickly recovered, however, adult abundance increasing nearly sevenfold during 1978–1981. In spring 1981 the bottom population in southern Lake Ontario was estimated to be 5.25 × 10 9 fish weighing 128,500 t. Estimated average alewife biomass per hectare during 1978–1982 far exceeded the estimates for either Lake Michigan during 1967–1982 or western Lake Huron during 1973–1982. Recruitment of age-II fish to the population was affected by abundance of adults in two ways: (1) the number of yearlings produced was directly related to adult abundance at low population levels but inversely related at high population levels; and (2) survival of yearlings to age II was inversely related to adult abundance. Growth in 1977 was exceptional, leaving a wide, unmistakable band on scales of the previously slow-growing adults. This wide growth zone served as a marker to identify survivors of the 1976–1977 die-off and to show that each year after 1978 a successively larger proportion of survivors was failing to grow in length or to form an annulus (54% in 1979, 96% in 1980, and 100% in 1981). There was no marker on scales of alewives recruited after the die-off, but the apparent age composition of our catches strongly suggested that most of them also failed to grow in 1981.

Transactions of the American Fisheries Society↗
USGS1986

Effects of five metals on susceptibility of striped bass to Flexibacter columnaris

Exposure of young striped bass Morone saxatilis (weight, 8.5–34 g) to a mixture of arsenic, cadmium, copper, lead, and selenium at 4 and 10 times the average environmental concentrations of 1–3 μg/L protected the fish from experimental infection with Flexibacter columnaris, the causal organism of columnaris disease. In four trials, all striped bass died within 7 d after a 2‐min exposure to 5 × 10 6 F. columnaris cells in untreated water. In contrast, no fish died after a single dayˈs exposure to the metal mixture followed by infection with F. columnaris and a second exposure to the metals for seven more days. When striped bass were exposed 5 d to individual metals, copper protected against infection and cadmium offered marginal protection but was slightly toxic after 2 d exposure. Arsenic increased susceptibility to infection, and lead and selenium were without an apparent effect.

Transactions of the American Fisheries Society↗