摘要:

Paddlefish, Polyodon spathula, moved to the upper reaches of Old Hickory Reservoir (a mainstem reservoir on the Cumberland River in north-central Tennessee) during the March-May spawning period and concentrated in the tailwaters of Cordell Hull Dam (Cumberland River) and Center Hill Dam (Caney Fork River). Paddlefish eggs were collected 5.6 km downstream from Cordell Hull Dam beginning 13 April, and larvae were found beginning 21 April 1977. No paddlefish eggs or larvae were collected in the Caney Fork River, presumably because the low temperature (11–11.5 C) of the Center Hill Dam discharge prevented spawning there. No paddlefish greater than 18 mm total length were taken by larvae sampling gear, and gill nets were ineffective in capturing young of year and yearlings. Paddlefish from 50 mm to 400 mm total length, however, were impinged on the intake screens at the Gallatin Steam Electric Plant on Old Hickory Reservoir in large numbers (approximately 9,000 from August 1975 to May 1976). Comparisons of lengths on capture dates with similar data reported in the literature demonstrated that the impinged paddlefish were young of year which attained approximately 300 mm total length by age I.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<157:EOPIOH>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The standing stocks and instantaneous rates of total, fishing, and natural mortalities of rainbow trout (Salmo gairdneri) and brown trout (S. trutta) in the Green River of southwestern Wyoming were estimated from creel-survey and catch-curve information. Six-year averages for rainbow and brown trout were, respectively: standing stock, 49.6 and 5.2 kg/hectare; yield from the sport fishery, 5.8 and 1.5 kg/hectare; instantaneous total mortality, 1.12 and 0.75; instantaneous fishing mortality, 0.20 and 0.44; instantaneous natural mortality, 0.92 and 0.31; rate of exploitation, 0.12 and 0.30. The primary factor limiting the standing stock is lack of instream cover. Fishing can probably be sustained at current levels by stocking rates of 200 or fewer trout/hectare.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<168:SCOTIT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Growth of the 1977 year class of largemouth bass, Micropterus salmoides, at West Point Reservoir was highly variable. A clearly bimodal length-frequency distribution evident by fall 1977 was not a result of disruption of spawning by temperature or water level fluctuations. The abundance of fish as prey was inadequate for small young-of-the-year largemouth bass after June 1977, but was adequate for the larger, fast-growing largemouth bass of the same year class. This difference in availability of suitable food was apparently instrumental in creating the growth disparity. Fry of gizzard shad, Dorosoma cepedianum, were collected in littoral areas with small largemouth bass but were not important as prey until the largemouth bass were longer than 25 cm. Although bluegills, Lepomis macrochirus, were the most abundant young of the year in littoral areas, they were not selected as food in proportion to their abundance.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<176:DGOLBI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The utility of in vitro uptake of14C-glycine into fish scales as an index of immediate past fish growth was validated for white suckers (Catostomus commersoni), carp (Cyprinus carpio), yellow perch (Perca flavescens), and bluegills (Lepomis macrochirus). Good correlations were found for all species between growth over 2 or 3 weeks and the amount of glycine taken up by scales; starvation of fish reduced the uptake considerably. Although glycine uptake was dependent on growth rate of the fish and not simply on temperature at which scales were incubated in glycine, the relationship of glycine uptake to incubation temperature was not constant for fish acclimated to different temperatures. Thus, growth comparisons could not be standardized to a particular temperature by a linear regression. In field applications, scales should be incubated at, and glycine uptake reported for, ambient temperatures.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<187:UOCBSA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Subadult striped bass, Morone saxatilis, tagged with temperature-sensing ultrasonic transmitters in April-October and monitored in freshwater lakes generally occupied waters of 20–24 C, when these temperatures were available. When they were not (spring and fall), fish occupied nearly the warmest water available at depths > 1.5 m. Excursions of less than 2 minutes duration to warmer and to cooler water than was generally occupied were common in spring and summer. A thermal niche for subadult striped bass of 20–24 C centering near 22 C, as suggested by these results, would have important implications for managing this species in fresh water.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<195:TOBTUS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The 1973 and 1974 year classes of adult, wild summer and winter steelheads (Salmo gairdneri) were genetically compared at five polymorphic enzyme loci: alpha-glycerophosphate dehydrogenase-1; lactate dehydrogenase-4; malate dehydrogenase-3,4; superoxide dimutase-1; and phosphohexose isomerase-3. Overall genetic differences between summer and winter steelhead groups were not significantly greater than genetic differences observed for 1973 and 1974 year classes compared within each group. These findings, in conjunction with field observations of known summer-winter steelhead spawning pairs, suggests that summer and winter steelheads in the Kalama River are not at present reproductively isolated.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<203:AGCOSP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The effects of a wide range of turbidity and turbulence levels on the short-term survival of Mysis relicta under laboratory conditions were examined. The levels of turbulence and turbidity used bracket the conditions which Mysis relicta may be expected to encounter in one area of Twin Lakes, Colorado during the operation of a pumped storage power plant. Turbulence caused a highly significant increase in mortality; mortality was not significantly affected by the three levels of turbidity tested (0, 735–779, and 1,470–1,558 American Public Health Association turbidity units of glacial flour sediments) nor by the interaction of turbidity and tubulence. Mortality of Mysis relicta subjected to turbulence increased significantly over the 8-day experiment. Exhaustion from inability to feed and from continuous swimming during turbulent periods is suggested as the possible cause of increased mortality observed over time during the experiment.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<207:MR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The downstream effects of channelization and agricultural drainage development were evaluated in southwestern Minnesota by comparing benthic invertebrate populations in streams heavily modified by channelization and agricultural drainage development in upstream areas with those not so modified. Physicochemical characteristics, as well as invertebrate populations, were observed in relatively undisturbed downstream reaches. Turbidity, total alkalinity, and timing of discharge were similar in all streams. Species compositions of benthic invertebrates were similar in all streams, and there were no significant differences in total, seasonal, or monthly levels of standing stock in either numbers or biomass between modified and unmodified streams. Invertebrate drift, both insects and total invertebrates, was similar in all streams. Some differences in individual taxa were observed, but these were related to localized differences between streams, rather than to drainage development. Specific differences included higher numbers in drift of the snail Physa gyrina and the amphipod Hyalella azteca in one modified stream, apparently the result of more suitable upstream habitat in drainage ditches. It was concluded that, in these agricultural areas, the impact of upstream drainage development on benthic invertebrates in natural downstream reaches was negligible.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<213:EOADDO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Eggs of Pacific herring, Clupea harengus pallasi, collected from Prince William Sound, Alaska were exposed to Prudhoe Bay crude oil for 4–144 hours, then returned to uncontaminated seawater for further development. Newly hatched larvae from both control and experimental groups showed no gross abnormalities. Transmission electron microscropy revealed inter- and intracellular spaces in brain and muscle tissues of exposed organisms but not in those of controls. Many mitochondria in the body muscle of exposed organisms were swollen, some with deteriorating cristae structure.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<224:UEOCOO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The twenty-four-hour median lethal concentrations (24-hour LC50) of total ammonia nitrogen (TA-N) to channel catfish (Ictalurus punctatus) at pH 7, 8, and 9 (total hardness, 40 mg/liter; temperature, 21–25 C) were 263.6 ± 11.3 (SE), 38.8 ± 1.8, and 4.5 ± 0.2 mg/liter, respectively. The 24-hour LC50 of un-ionized ammonia nitrogen (UIA-N) concentration at pH 8 was significantly higher (1.82 ± 0.06 mg/liter) than at pH 7 or 9 (1.39 ± 0.06 and 1.49 ± 0.12 mg/liter). Enrichment of the water to 440 mg/liter total hardness at pH 7 significantly increased the 24-hour LC50 of TA-N and UIA-N (356.3 ± 16.4 and 1.79 ± 0.07). Fish exposed to 25 mg/liter TA-N for 12 hours at pH 7 and 8 showed no differences from control fish in hematocrit, percent total plasma protein, or plasma and muscle chloride. Plasma sodium showed no difference between control and experimental groups at pH 7; however, a significant decrease occurred in fish exposed to 25 mg/liter TA-N at pH 8. No differences in blood pH were found between the control groups and fish exposed to 100 and 200 mg/liter TA-N at pH 7, and to 10 and 25 mg/liter TA-N at pH 8. Plasma sodium depletion is suggested as a contributing mechanism of ammonia toxicity.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<229:EOEPAC>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor