摘要:

Quantitative and qualitative analyses of organisms eaten by mountain whitefish in the Snake River were undertaken. Abundance of an organism in a whitefish stomach appears to be dependent upon the organism's overall availability. The stomach contents of all size classes differed in taxonomic composition. Overlap in the taxonomic categories of food organisms eaten by fish of size classes II and III was about 50%.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<764:FHOTMW>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

An objectionable “earthy-musty” flavor is frequently found in intensively-cultured catfish which renders the fish unmarketable. Fifty-gram channel catfish were held in 150-liter stainless-steel tanks containing dense masses of either Symploca muscorum or Oscillatoria tenuis to determine the capability of these geosmin-producing blue-green algae to impart this type of offflavor in the fish. Within 2 days the fish had acquired distinct earthy-musty flavor similar to the odor of the algae. Flavor intensity reached a maximum at 10 days. When fish which had been in the algae tanks for 14 days were transferred to flowing, charcoal-filtered water, the flavor disappeared after 10 days. Fish held in tanks containing algae-free filtrate from the algae culture tanks acquired the off-flavor but at a slower rate than the fish in the culture tanks. This indicated that the fish could absorb the flavor compounds without ingesting the algae, possibly across the gill membranes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<774:ABCCOE>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Commercial fishing statistics for lake whitefish (Coregonus clupeaformis), shallow-water lake herring (Leucichthys artedii), yellow perch (Perca flavescens), and suckers (Catostomus spp.) were analyzed separately by principal gears in the fishery for a 42-year period in northern Green Bay, Lake Michigan. The transition from cotton to nylon gill nets occurred 20 years after records began while the pound net remained unchanged. Abundance indices calculated separately for each gear and catch-per-unit-of-effort (CPE) averages for each gear did not show a general increased efficiency for nylon gill nets.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<778:TREONG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

A study of the reproduction of Ezicymba buccata Cope in Vigo County, Indiana is based on changes in tuberculation in males, condition of the ovary, size and number of ova, and length frequencies of young-of-the-year. Levels of tuberculation are described and prove to be reliable indices of reproductive maturity. Temporal changes in the degree of tuberculation and condition of the ovary as well as changes in number of ova indicate a spawning period from the end of April to at least the end of July. Early in the spawning season both age group II and III males and females contribute most to the breeding population and the larger specimens spawn earlier. Projection of the growth in initially moderate sized ova and lack of abrupt differences in ova size in spring suggest that individual females in age group II spawn more than once within the spawning season. Most age group III males and females die shortly after spawning. Later in the summer (July) large age group I males and females probably breed. Study of ova size and number as well as ovary condition indicates two major spawnings, one in early May and the other in late June or early July. Monthly length frequency distributions of young also indicate two spawning peaks. Long breeding season, fractional spawning of age group II and the late summer spawn of age group I all are adaptive to streams with a shifting sand bottom.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<786:ROTSME>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The life histories of the mimic shiner (Notropis volucellus), the common shiner (N. cornutus), and the bluntnose minnow (Pimephales notatus), from a small Minnesota Lake, were compared in order to find out how temperate fish species segregate ecologically and how accurate dietary studies are for showing ecological differences among similar co-existing species. The three minnow species were found to differ from each other in habitat, feeding behavior, organisms consumed, population age structure, and breeding habits. Mimic shiners occurred in large schools in shallow water and fed during the day, with peaks at dawn and dusk, on emerging and flying insects. They usually spawned in August but did not spawn at all in some years. Bluntnose minnows were found in small schools both in shallow water and in silty bottomed clearings in the aquatic vegetation in deeper water. They fed continuously on bottom organisms and detritus and spawned in July. Common shiners were roving opportunists, feeding on whatever organisms were most abundant. Their numbers fluctuated considerably but they were usually less abundant than the other two species. They spawned in June. All three cyprinids were ecologically segregated from the noncyprinid species in the lake as well. It was found that dietary studies can be reasonably good indicators of ecological differences if enough samples are taken at a variety of times and locations.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<794:ESATSO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The respiratory activity of three aquatic animals, selected from different pollution index classifications, was examined in the presence of sublethal concentrations of Dibrom, a commonly used, broad spectrum, organophosphate insecticide. The oxygen consumption of Hydroperla crosbyi (Needham and Claassen), Corydalus cornutus L. and Notemigonus crysoleucas (Mitchill) was measured in a specially designed flowing-water respirometer, housed in an environmental chamber.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<806:TEODOR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Field experiments were conducted in the northeastern Gulf of Mexico to evaluate techniques for using sequentially-operated lamp strings and moving lamps to lead and concentrate light-attracted coastal pelagic fishes. Fish were successfully led between sequentially-operated under-water lamps separated by distances up to 20 meters. Mobile lamps were used to lead fish distances up to approximately 1 kilometer. Fish aggregations which form daily around man-made structures were held after dark and led clear with moving lamps for capture by purse seine. A combination of nightlighting and man-made structure fish attraction techniques are proposed for harvesting coastal pelagic fish aggregations which occur around existing petroleton drilling platforms, well heads, and other areas presently inaccessible to conventional fishing gear.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<816:AACCPF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Experiments in the brackish water culture of rainbow trout (Salmo gairdneri) were conducted from 25 November 1971 to 24 March 1972 to determine the feasibility of providing a supplemental cash crop in the coastal water of Alabama during the winter. During this period trout were raised from an initial weight of 93.8 g to 354.8 g when stocked at 196 fish/m3and 322.3 g when stocked at 392 fish/m3. Rainbow trout acclimated easily to brackish water and their potential to southern mariculture appears promising.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<826:BWCCOR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Three toxicants were tested individually, and mixtures of two of them were tested for toxicity to fresh-water ostracods (Cypretta kawatai) in laboratory static bioassays at 24 ± 1 C. The 96-hr LC50 values were: antimycin A (95.5%), 7.40 μg/1; TFM (95.7% 3-trifluormethy1–4-nitrophenol), 7.10 mg/1; Bayer 73 (70% 2-aminoethanol salt of 2',5-dichloro-4'-nitrosalicylanilide), 1.16 mg/1. The toxicity of a 50:50 mixture of TFM and Bayer 73 was simply additive (96-hr LC50, 3.03 mg/1), whereas a 98:2 combination of TFM and Bayer 73 was slightly synergistic (96-hr LC50, 5.00 mg/1).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<829:ATOAAB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Digestibility studies of channel catfish were conducted with purified rations and commercial catfish feeds. The chromium oxide indicator method used in this study appeared to be satisfactory for determining apparent protein digestibility in foods with channel catfish. Desirable features of our procedure were that the fish consumed food approximating 2% of body mass voluntarily and feces for determining digestion coefficients were collected exclusively from the rectum. Derived digestion coefficients with practical diets indicated that digestion coefficients in livestock feeding tables for concentrated feedstuffs may be applied to catfish feeds.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1973)102<831:DOAPDI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor