摘要:

A model useful for managing interacting fish species, based on concepts of food competition, is developed and tested.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<215:ACMOBD>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The ecological impact of fish hatchery wastes on periphyton production rates and oxygen balance were determined in the Jordan River from March through June, 1971 and 1972.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<226:PEOFHD>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A naturally occurring fish kill took place during the southern Florida dry season when receding water levels forced aquatic organisms out of shallow swamps and into a small pond. Physico-chemical parameters of water quality varied greatly from their usual range as did the abundance of phytoplankton which reached a peak of 2.5 X 109cells per liter. The fish kill had no effect on the long-term limnological characteristics of the pond, as water quality returned to normal range within 2 months and phytoplankton disappeared within 1 month after the fish kill. The species of fish in the pond showed a range of susceptibility to low oxygen concentration and other aspects of the fish kill. They were classified into three categories based upon their survival: Notemigonus crysoleucas, Lucania goodei, and all centrarchids were eliminated rapidly; Fundulus chrysotus, Poecilia latipinna, Heterandria formosa, and Ictalurus natalis were either eliminated late in the fish kill or survived in numbers lower than measurable by methods used in this study; Lepisosteus platyrhincus, Gambusia affinis, Jordanella floridae and the prawn Palaemonetes paludosus survived the fish kill in moderate densities of 0.6 to 6 individuals/m2In three species of Lepomis, larger fish died before smaller ones. Six of 22 species of fish and only 0.6% of the previous fish population survived the fish kill.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<235:EOANFK>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The lowest concentration of methylmercuric chloride (MMC) and mercuric chloride added to Lake Superior water that caused a significant increase in cough frequency in brook trout was 3 μg Hg/liter. Cough frequency is a good short-term indicator of the long-term effects of MMC. The response can be used to predict the safe concentration of mercuric chloride since the long-term effects of this compound are not known. Increases in cough frequency were proportional to the concentration (from 3 to 12 μg Hg/liter) of both compounds at pH 7.5. The fish were more responsive to MMC when the pH of the test water was lowered to 6.0; response to mercuric chloride was not changed by lowered pH. Fish exposed to MMC at pH 6.0 contained more total mercury in their gills and red blood cells than fish tested at pH 9.0. The uptake of mercury by brook trout exposed to mercuric chloride did not differ significantly at pH 6.0 and 9.0.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<244:CRAUOM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Similar patterns of dispersion were observed over 90-day periods among hatchery-reared rainbow trout and rainbow-steelhead hybrid trout released in the Lake Washington system in 1966 and 1967. In both experiments 90% of recaptures were within 3.2 km of the release site. Returns were generally the same for the three tags tested (Carlin dangler, Petersen disk, Floy anchor pendant). Of the total fish released in 1966, 47.3% were recovered, and of those in 1967, only 40.5%. A reward was offered in the 1966 experiment. Loosening and loss of tags and infection of tag wounds appeared minimal.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<250:TRAMOR>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Bottom trawl samples showed that there were diel changes in bluegill abundance in limnetic areas of Lake Wingra, Wisconsin, from April to November 1970. Catches during daylight were greater than those at night. Sampling both littoral and limnetic habitats during September, when diel migrations appeared most dramatic, indicated that fish moved onshore after sunset and offshore after sunrise. All size classes sampled appeared to participate in these movements. Larger fish predominated in littoral areas, suggesting either longer residence time during a did cycle or a proportionately larger resident population. Stomach analyses indicated that bluegills ate mostly zooplankton in limnetic areas, whereas macrofood organisms such as insects dominated the prey of littoral zone fish. Quantitative comparisons of stomach content demonstrated that smaller fish benefited most from the offshore migration.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<255:DPODAF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The principal diet of age I+ winter flounder Pseudopleuronectes americanus captured in the Weweantic River Estuary, Wareham, Massachusetts was comprised of polychaetes, bivalves, gastropods, and crustaceans. During spring, flounder fed on planktonic crustaceans found within the estuary and during the summer and fall on mollusks and polychaetes at the estuary's mouth.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<261:FHOYWF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A summer food habit study was conducted on 300 specimens of the black sculpin, Cottus baileyi Robins, collected from the upper South Fork Holston River and four tributaries in southwestern Virginia from July to October 1966. Frequency of occurrence, average number, and percent of total were determined for all organisms occurring in the stomachs. Analysis of stomach contents revealed a diet consisting almost exclusively of immature aquatic insects encompassing a wide range of morphological and behavioral differences. Cottus baileyi fed throughout the daylight hours taking whatever was available. Forage ratios ranging from 0.1 to 10.3 were determined for a selected group of insects that represented a wide diversity of habits. Baetis, Pseudocloeon, Antocha, and chironomids had forage ratios greater than 1.0. Baetids and chironomids were the most important food items in the diets of all sizes of fish. Habits of insects largely determined the extent they were preyed upon by C. baileyi.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<270:SFHOTB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

During 18 months of electrofishing a sample of 991 adult largemouth bass (Micropterus salmoides) was taken from Crab Orchard Lake. The stomach contents were removed in the field with a gastroscope. Gizzard shad (Dorosoma cepedianum) constituted the principal forage fish. Approximately 50% of the bass collected had empty stomachs. As the size of bass increased, the food intake as a percent of body weight decreased. Ninety percent of the bass stomachs contained one food item. When more than one food item was found, they were usually in the same stage of digestion. It is suggested that the high percent of empty stomachs was related to hunting success, or that the onset of the feeding stimulus in association with rate of digestion might result in a periodicity of feeding that involves a high percent of empty stomachs. A higher relative intake of food by small bass was postulated to be a result of the bass's typically consuming only one fish. Inasmuch as the forage fish were relatively uniform in size, one fish constituted a large meal for a small bass but not for a large bass.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<277:FIOTLB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Tilapia andersoni, T. macrochir and T. rendalli account for a large portion of the 6,000-metric-ton fish catch taken each year from the Kafue floodplain in Zambia. The Kafue Gorge Hydroelectric dam, completed in late 1970, altered the natural flooding regime on much of the floodplain. From April 1969 to August 1970, I studied these species of Tilapia in a sector of the Kafue floodplain as one means of predicting the effects of the Kafue Gorge dam. I determined ages of these Tilapia species from scale samples and calculated growth of each fish during preceding years. The growth of Tilapia varied significantly from year to year. The extent of seasonal flooding correlated positively with growth of younger Tilapia of all three species.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<281:GOTOTK>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor