摘要:

Tagged Atlantic menhaden, Brevoortia tyrannus, along with nontagged controls were held captive in a natural cove at Beaufort, North Carolina from December 1970 to January 1972. Rate of growth, annulus formation and increase in scale diameter was the same for control menhaden and those tagged one, two or three times. Growth of fish in the cove was similar to all other previous estimates obtained from back-calculated length-frequency studies. Both development of scales and growth of fish were correlated with annual temperature changes, and only one annulus formed during the year. Larval menhaden, which were thought to require water of low salinity to metamorphose into normal juveniles, transformed in the cove where the salinity was 30 ‰. An “inner ring,” which forms on the scales when menhaden are 50 to 70 mm and occurs on about 15% of the scales from commercial Atlantic menhaden landings some years, may represent a true annulus formed by very small juveniles from Long Island Sound, New York.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<292:GAFAFO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A direct relationship existed between standing crops of zooplankton and distribution, growth, and feeding of young-of-the-year blueback herring, Alosa aestivalis, in the James River, Virginia. Zooplankton densities were highest upstream where food consumption and growth rates were correspondingly highest. A progressive downstream decrease and upstream increase in fish abundance occurred during the study. Condition (K) decreased after flooding from Hurricane Camille.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<297:DGSFAE>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

During 1966 and 1967, the spawning runs of an anadromous population of alewives, Alosa pseudoharengus (Wilson), were studied in Bride Lake, Connecticut. Alewives entered the lake from Long Island via Bride Brook from March to June. The number of fish entering the lake each day varied and was not related to water temperature or amount of moonlight. Males predominated among early migrants, whereas a 1:1 sex ratio existed through the later part of the migration. The average size of adults decreased as the migration progressed. Adults spent from several days to 3 months on the spawning grounds, the males outnumbering the females. Counts of the number of fish entering and leaving the lake indicated that high mortalities occurred. Females spawned from 48,000–360,000 eggs. The total number of eggs spawned in the lake was estimated to be 2.0 X 1010.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<312:SOTAAA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

We studied the effect of severe fluctuations in flow on the distribution of bottom fauna of the upper Kennebec River. During the years 1964–1970, discharges below Wyman Dam ranged from 8.5 m3/sec to an average daily high of about 170 m3/sec. Slow currents resulting from low flows appeared to limit the diversity and abundance of swift-water aquatic insects on the river-bottom below the dam. Sampling stations above the impoundment averaged 19 aquatic insect genera, while those below the dam averaged 11. About 19 genera were found at stations where the current near bottom fluctuated from 0.5 m/sec to 0.9 m/sec while only 4 genera were found at stations where the fluctuations were from 0.1 to 0.5 m/sec. Aquatic insects adapted for swift water such as Rhyacophila, Chimarra, Iron, Blepharocera, Acroneuria, and Paragnetina were more abundant above the impoundment than below, and were absent from those stations below the impoundment with the lowest current velocities.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<318:TEOWFM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The daytime abundance and localized distribution of fishes in relation to temperature were studied in a small tidal cove by beach seining on seven dates in the Back River estuary, Maine, during the summers of 1971 and 1972. Temperatures on the seven dates ranged from 15.1–26.2 C, and salinities ranged from 17.3–24.7‰. Eighteen species of fishes were captured, with mummichogs, smooth flounders, Atlantic silversides and Atlantic herring together comprising over 98% of the catch. Mummichogs and Atlantic silversides were captured primarily near the inner end of the cove, while other abundant species were caught mainly at the outer end of the cove. Several species seem well adapted to naturally warm cove temperatures. Others seem now virtually excluded because of warm temperatures. Winter flounder, Atlantic herring, and Atlantic tomcod might be excluded from the cove during daytime in summer if artificial warming of the cove were permitted.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<325:SAOFIA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Tests were conducted to determine the upper incipient lethal temperature and critical thermal maximum (CTM) for mosquitofish acclimated to 25.0 C and 35.0 C, the effects of various cyclic thermal acclimation regimes on the CTM, and the effects of severe daily heat stress on the CTM. Heat tolerance of mosquitofish subjected to brief daily exposure to temperatures approximating or exceeding the upper lethal limit was increased over that obtained with constant temperature acclimation in proportion to the peak temperature of the cycle.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<331:TEOATC>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Increases in plasma lactate and glucose concentrations, along with decreases in plasma chloride and liver glycogen concentrations, were observed in muskellunge in response to capture and handling. Holding muskellunge in 0.3% NaCl alleviated some of the physiological symptoms of stress, but holding the fish in the lake for 48 hr before release had no effect. Physiological responses to fin-clipping and transport by truck were slight in comparison to that of original capture. Salt treatment and reduction in duration and frequency of handling is recommended.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<336:PROHRM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Northern pike, Esox lucius Linnaeus, collected from two regions in Ontario from 1961 to 1969, were studied to determine what characteristics and procedures might be used to externally separate the sexes. Spontaneous passage of reproductive products from the urogenital pore is the most accurate indicator of sex but can be used to differentiate such a small percentage of individuals annually that its value is limited. Even when stripped during the spawning period, only 82% of the mature males and 76% of the mature females yielded reproductive material. Differential body form alone is not a satisfactory indicator of sex. Sexing northern pike by the external appearance of the urogenital region is described. This technique can be applied to both mature and immature northern pike regardless of season. Accuracy of the method was tested throughout the year. Monthly averages of autopsied mature fish revealed that the urogenital technique was used to correctly sex 91% of the males and 94% of the females.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<343:ESDONP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Most of the usual methods for studying fish populations have been ineffective when applied in the shallow, freshwater marshes of southern Florida. Exceptions are devices which trap fish by rapidly enclosing a known area of marsh. Of these, pull-up traps are best suited for sampling large areas for relatively large or widely dispersed fish, whereas drop traps with bottom nets are the most efficient for studies of small species at permanent sampling sites. Each produces comparable but consistently biased results due to habitat disturbance. The most precise data on shallow water fish communities are obtained by use of bottomless drop traps which are moved to new sites for each sample.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<348:QSOFPI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Corrections are made to an earlier paper by Jensen (1971). The predicted yield from an unstable population is compared to that from a stable population. It is shown that an unstable population will reach a stable structure, following which the yield will not fluctuate but go steadily down. Data from the population indicate that it is on its way towards extinction, even without additional mortality imposed on any age group.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1974)103<353:OPTYFB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor