摘要:

Examination of 1,323 American smelt, Osmerus mordax (Mitchill), from the Great Bay region of New Hampshire during the period from October 1951, through April 1952 showed that 308 (23.3 percent) were infected with Glugea hertwigi. The serious pathological manifestations of the disease suggested that it is an important contributing factor to the recent decline in the smelt population of the area. Although the mode of transmission of the parasite from smelt to smelt is not known, it seems probable that it enters with the food–perhaps after prior mechanical concentration of the spores by one or more of the organisms utilized by the smelt for food. Additional study is needed on the problem of transmission.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[84:MPGHIA]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor

摘要:

A total of 1,055, scale samples from tagged, recaptured brown trout, rainbow trout, and brook trout and 129 scale samples from planted, marked rainbow trout were taken from Prickley Pear Creek, Montana, between June 1949 and October 1951. In addition, scale samples were obtained from 69 rainbow trout planted as fry in Savage Lake, Montana, and from 42 known-age rainbow trout of the brood stock at the U. S. Fish and Wildlife Service Fish Hatchery, Ennis, Montana. Studies of these scales substantiated the general validity of the scale method of aging wild trout and trout planted as fry or young-of-the-year fingerlings.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[91:VOADFS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor

摘要:

The effects of variations in volume of solution of toxicant, aggregation, temperature, and change in condition of test animals during time of holding in the laboratory were investigated with regard to possible influences on bio-assay results. The western gambusia, Gambusia affinis affinis (Baird and Girard) was used as the test animal. In spite of relatively favorable experimental conditions, it seems that estimates of relative toxicity are affected by uncontrolled variations which greatly limit dependability.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[104:BPFTEO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor

摘要:

A large proportion of the current fishery research literature is cluttered with superfluous mathematical material, such as numbers expressed in too many significant digits or decimal places, data written more precisely than is justified by the experimental procedure, or complicated formulae and equations. This criticism applies particularly to papers published in the Transactions of the American Fisheries Society, a professedly practical journal. Much of this redundant matter could be omitted, with no appreciable loss in clarity or meaning; however, cases vary, and it is impossible to set any hard and fast standards of form.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[115:DPOROF]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor

摘要:

Gorge Creek, a typical small mountain trout stream on the eastern slope of the Rocky Mountains, was used in a test to measure survival and weight changes in hatchery-reared cutthroat trout (Salma clarki). A resident population of this species exists in the stream. The experimental procedure was to introduce groups of trout into enclosures 1/2 to 3/4 mile long; each trout in a group was given a numbered Petersen tag and weighed before planting. Recapture by angling and reweighing were carried out throughout the season of planting and also in later summers. In this way six lots of pond-reared, one lot of stream-reared, and one lot of transplanted wild cutthroat trout were studied. Pond-reared fish exhibited very low survivals over the first (0 to 4.9 percent) and second (0 to 3.1 percent) winter. Survival was largely independent of age. Transplanted wild trout showed survivals of 46.0 to 29.0 percent to the second and third summers, respectively. Stream-reared hatchery fish gave an intermediate value (17.2 percent to the second summer).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[120:CSOWAH]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor

摘要:

The Red Lakes in northwestern Minnesota comprise 275,000 acres of water which support a commercial fishery producing up to 1.5 million pounds of fish per year. Walleye, Stizostedion vitreum vitreum (Mitchill), and yellow perch, Perca flavescens (Mitchill), are the principal species. Statistics for the past 37 years have been analyzed and fluctuations in the abundance of the important species calculated for the 24-year period, 1930–1953. The fishing is carried on exclusively with 3 1/2-inch-mesh (extension measure) gill nets by Chippewa Indians and the catch is marketed through a cooperative fishery enterprise. There have been wide fluctuations in the abundance of principal species but, although fishing effort has increased greatly during the past few years no trends have developed. Changes in walleye abundance have been shown to be independent of changes or levels of fishing effort, and to be determined by strength of individual year classes. Gear competition has no effect on abundance estimates. Strength of year classes is not correlated with size of brood stock, abundance of competing species, or amount of hatchery fish planted. Weather conditions cannot be correlated with observed changes in strength of year classes. Implications for management include provision of adequate prediction of abundance, and annual adjustment of fishing practices to make greatest use of the available stock. Gear limitations should be designed to secure harvest at optimum size of fish and to provide a suitable economic status for the fisherman.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[131:FIPAAO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor

摘要:

The redside shiner (Richardsonius balteatus) was introduced into Paul Lake, British Columbia about 1945 and by 1952 was abundant in the lake. Some effects of this introduction on Kamloops trout (Salmo gairdneri kamloops), previously the only other species of fish in the lake, are described. The summer diet of trout underwent marked changes and in 1952 shiners constituted a main item of diet for trout longer than 30 centimeters, fork length. Average stomach volumes of the smaller trout decreased subsequent to introduction of shiners. Growth rate declined and trout did not reach legal size (roughly 20 centimeters) until they were more than 2 years old. Previously, yearling trout had contributed substantially to the fishery. Change in growth rate has intensified the selection by the sport fishery of faster growing fish. A decline in the success of fishing and a drop in angling pressure have resulted in a decrease in catch to less than one-half of the previous annual total. These changes are discussed in relation to predation by shiners on trout fry, predation by trout on shiners and competition for food between shiners and trout.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[161:SEOIOT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor

摘要:

A study of the life history of the black crappie Pomoxis nigromaculatus (LeSueur), from Lake George, Florida, was made in 1949 and 1950. Few previous attempts to determine the age of fish from Florida waters have been made because of several difficulties in reading scales. Scale readings of 943 black crappie revealed that the 1947 and 1948 year classes were stronger numerically than the 1949 year class. The readings also indicated that few fish reached the IV group or older. Males and females showed only minor differences in growth. Calculations of growth from scale measurements yielded the following estimates of length at the end of the first five years of life: first–4.4 inches; second–8.1 inches; third–9.9 inches; fourth–11.5 inches; and fifth–12.5 inches.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[176:LHOTBC]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor

摘要:

Several earlier researchers have pointed out that trout and salmon fry hatched under gravel are hardier than those reared in a hatchery. The present report confirms these observations, and tries to delineate the effect of certain environmental factors on the embryonic development of salmon fry. Salmon fry (Salmo salar) hatched under gravel were better developed, more deeply pigmented, and on the average 15 percent heavier than those hatched in troughs. The average number of vertebrae was significantly influenced by solar radiation and by gravel cover. The separate effects of these two environmental conditions tended to obscure one another. Vertebral malformations were numerous in fry hatched under gravel in total darkness. Mortality, caused by blue-sac disease at the time of the spring run-off of snow water was less among brown trout (Salmo fario) alevins hatched in gravel than among hatchery reared alevins. Rainbow trout (Salmo gairdneri irideus) fingerlings hatched under gravel were less vulnerable to predators (eels) than fingerlings hatched in hatchery troughs.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[194:EOSRAO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor

摘要:

A study of the redeye bass, Micropterus coosae Hubbs and Bailey, was conducted on Sheed's Creek in southeastern Tennessee during the years 1950 through 1953. This fish is common in Georgia and Alabama and also occurs in several small streams in Tennessee. The redeye bass is primarily a fish of small upland streams and is seldom found in lakes or ponds. In comparison with other black basses, the redeye bass has an average life span, grows slowly, and is relatively slender. Of the 6,363, redeye bass scales examined 82 percent were regenerated. This occurrence of scale regeneration was higher than in 13 other species of fish in eastern Tennessee streams. This report on the redeye bass includes information on the standard length-total length relationship, length-weight relationship, growth rate, parasites, food habits, spawning habits, fecundity, maturity, distribution, migration, and angling importance. The redeye bass has been propogated successfully in Tennessee hatchery ponds and has been introduced experimentally into 10 small streams of middle Tennessee that have proven to be unsuitable for either warm-water game fish or trout.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1953)83[202:GAHOTR]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1954

数据来源: Taylor