摘要:

The 24-hour activity patterns of young and adult black bullheads have been investigated in a pool of a Wisconsin stream as well as in the laboratory. The young were found to exhibit two primary feeding periods in nature, one around dawn and the other around dusk. The young swim actively in schools during most of the daylight hours with an apparent depression of activity occurring around midday. They appear to be relatively inactive at night. Adults apparently remain inactive in the weed beds during the daylight hours, but they move around extensively at night. Trapping evidence suggests that the adults tend to forsake the pool during the early hours of darkness and return shortly before dawn. Feeding of the adults takes place after dark, but its exact timing is unknown. Behavior of the bullheads appears to be controlled by a combination of internal and external factors. Internal factors include hunger and “social appetite.” External factors include food, other bullheads, and possibly light.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[1:DPITBB]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor

摘要:

The standing crops of fishes which inhabited three small lakes were estimated immediately after rotenone treatment by combinations of procedures which included collections of all fish along the shorelines, from the surface waters offshore, and from the bottoms in shallow water; collections and counts from random sampling areas on shore and in shallow water; and collections and counts from randomly selected transect lines on bottom in deep water by SCUBA divers. Estimates of the net primary productivities of the lakes were made by the C14method. When the lakes are ranked according to their estimated standing crops, the order of ranking is confirmed by the estimated net primary productivity of the most productive lake, but is in conflict with the productivity estimates from the intermediate and least productive lakes. Analyses of the structures of the fish populations of the lakes before reclamation and evaluations of techniques are also presented.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[9:SCOFIT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor

摘要:

Acute toxicity of an alkyl benzene sulfonate (ABS) surfactant detergent to five species of juvenile estuarine fishes was determined at 20‰ salinity and 20° C. Concentrations of detergent that will kill 50 per cent of the test organisms in 96 hours ranged from 7.0 parts per million (ppm) for silversides, Menidia menidia, to 22.5 ppm for mummichogs, Fundulus heteroclitus. Intermediate in susceptibility were mullet, Mugil cephalus (10.1 ppm), winter flounder, Pseudopleuronectes americanus (8.2 ppm), and eels, Anguilla rostrata (7.5 ppm). After 12 weeks in solution, the synthetic detergent (syndet) retained most of its toxicity. The stock syndet contained 30.3 per cent ABS at week zero as determined by the methylene blue method.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[26:SEOASD]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor

摘要:

Estimates of the numbers of young-of-the-year and mature (age-groups I and older for the brook trout, and 9 inches and longer for the brown trout) brook and brown trout present in Sections B, C, and D of the Pigeon River were made each September 1949-60. Correlation coefficients (r) were calculated for the numbers of young-of-the-year trout and groundwater levels in October as measured in feet below land-surface datum at an observation well within the Pigeon River drainage. Calculation of the difference between the average minimum discharge (in cubic feet per second) at two streamflow gaging stations on the Pigeon River indicated the well measurements were reflected in the flow data. For the 9 years of available data, 1949-57, there was a highly significant linear correlation between numbers of young-of-the-year brook trout and groundwater levels; for the brown trout no correlation was evident. During years of high groundwater level, large numbers of young-of-the-year brook trout were present. Correlation coefficients calculated for the number of mature trout estimated to be present each September and the number of young-of-the-year trout present the following September, for 11 years of data, 1949-60, were nonsignificant for both brook trout and the brown trout. Analyses of variance of regressions of young-of-the-year trout on groundwater levels and mature trout for the years 1949-57 agreed essentially with the correlation coefficients.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[32:ROYTTM]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor

摘要:

Net production of juvenile coho salmon was estimated in three small streams in Oregon for 4 consecutive years. Annual net production of coho was greatly different in the 4 years, but production per unit area was similar among streams, averaging about 9 g/m2per year. No significant differences were found among streams in production per unit area for 14 months from emergence of fry one spring through seaward migration the next spring. For 4 years biomass averaged 5-12 g/m2shortly after emergence of fry, declining to 2-3 g/m2by July and remaining at about 2-4 g/m2until emigration of smolts in the following spring. In all years, mean production declined from 1.9-2.8 g/m2per month after emergence to 0.2-0.3 g/m2per month in winter, then increased to 0.5-0.6 g/m2per month prior to emigration. Monthly instantaneous growth rates were highest shortly after emergence of fry, declining until late winter, then increasing just before smolt emigration. The mean monthly instantaneous growth rate was about 0.19 for all streams and years. Yield of smolts as seaward emigrants ranged from 18 to 67 per 100 m2. Net production was 1.5 to 3.0 times greater than yield as biomass of smolts. Net production of all fish in one stream containing coho, steelhead and cutthroat trout, and cottids was estimated to be 16 g/m2per year and compared with data from other waters. Relatively large freshets appeared to cause large downstream movements of juvenile coho. Downstream drift of postemergence fry and emigration of yearlings tended to bias estimates of growth and net production in the residual populations.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[40:NPOJCS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor

摘要:

An exogenous strain of cultured Hexamita salmonis (Moore) was employed to induce trophic hexamitiasis in otherwise disease-free juveniles of coho salmon (Oncorhynchus kisutch) and steelhead trout (Salmo gairdneri). Mortality and growth were the parameters used to detect the effects of hexamitiasis on the two species. Two levels of each of the three experimental factors under study, Hexamita infection, species of fish, and density of fish, were arranged in a three-way factorial design. Replicate lots involved a total of 1,440 fish held under controlled laboratory conditions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[53:EHIJCS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor

摘要:

Samples of flesh were excised from the middorsal region of 67 siscowets (Salvelinus namaycush siscowet) and 46 lake trout (Salvelinus n. namaycush) collected from Lake Superior. Chemical analysis of the samples revealed a range in fat content (dry weight) of 32.5 to 88.8 per cent in siscowets and 6.6 to 52.3 per cent in lake trout. Percentage fat increased progressively with increase in length of fish in both forms, but the average rate of increase was far greater for siscowets than for lake trout at lengths between 12 and 20 inches. Despite substantial individual variation, the percentage fat in the two forms was widely different and without overlap at all comparable lengths. The range in iodine number of the fat was 100 to 160 for siscowets and 103 to 161 for lake trout; average values were generally lower for siscowets than for lake trout among fish of comparable length. Percentage fat and relative weight were not correlated significantly in either subspecies. The fat content of flesh samples from a distinctive subpopulation of Lake Superior lake trout known as “humpers” was more closely similar to that of typical lean lake trout than to siscowets, but the rate of increase in fat with increasing length was greater than for lean lake trout. Flesh samples from hatchery-reared stocks of lake trout, hybrid lake trout X siscowets, and siscowets tended to support the view that the wide difference in fat content between siscowets and lake trout is genetically determined.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[62:FCOTFO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor

摘要:

Humper lake trout are one of the several races or subpopulations of lake trout in Lake Superior. This study is based on 3,705 fish collected on a reef south of Isle Royale near the eastern end. The mean lengths of humper trout from commercial gill nets were smaller than those of lean lake trout. Members of age-groups VII, VIII, and IX represented 81.5 per cent of the commercial humper catch. The body-scale relation was described by two intersecting straight lines. The weight of humper trout increased as the 3.282 power of the length. Growth in length was slow and ranged from 1.6 to 3.5 inches per year. Annual increments were greatest in the first, sixth, and seventh years. Growth in weight was also slow but increased each year. Humper trout became legal (1 1/2 pounds) in the eighth year of life and reached 5 pounds in 11 years. All fish longer than 19.1 inches and older than age-group VIII were mature; the shortest mature fish were: males, 12.7 inches; females, 14.7 inches. At minimum legal size, 98 per cent of the males and 56 per cent of the females were mature. Humper trout produced an average of 1,351 eggs per fish or 516 per pound.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[75:AGMAFO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[84:AVITRT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659(1965)94[88:EOPOSO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1965

数据来源: Taylor