摘要:

The use of the electric shocker in the salvage of rainbow trout (Salmo gairdnerii) from an irrigation canal is described. An account is given also of physiological effects observed during shocking and the morphological effects determined by dissection. In order to determine the effects of shocking, the trout were transferred to a holding pond at a state fish hatchery and observed for 2 to 5 days before being released.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[61:SHEOTE]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

This paper covers the findings of 10 years of research on the problem of the low fertility of brown trout eggs (Salmo trutta) at the Jonkershoek Inland Fish Hatchery, Stellenbosch. As a background to the problem a brief résumé is given of the acclimatization of trout in South Africa with which the development of the Jonkershoek Hatchery has been closely associated.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[65:TFOBTE]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

A biological survey of Great Slave Lake was begun in 1944 in order to estimate its capacity for fish production before commercial fishing began. This great inland lake of 10,500 square miles was found to have a fairly heavy population of desirable fish with lake trout, lake whitefish, and ciscoes predominating. Physical, chemical, and biological evidence suggested a capacity for sustained production not unlike that of the upper Great Lakes and Lake Nipigon. A first estimate of 3 to 5 million pounds per year was made in December 1944. Commercial fishing began in 1945 and has now increased to a point where production is 3.7 million pounds per year. General biological studies extended over 4 years, and a continuing program has been established to follow the effects of fishing on the fish population. This lake affords a unique opportunity for the scientific investigation of a large fishery and for the conservation of an important natural resource.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[81:ETFPOG]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

During experiments in 1945 and 1946 in which sulfamerazine in the food was found to be effective in the treatment of furunculosis in brook trout (Salvelinus fontinalis), it was observed that fish grew faster on untreated food and that when the dosage rate was heavy they did not eat all the food and showed a dislike for it. To determine the effect of sulfamerazine treatment on growth and to learn whether the drug injures various trout species, brook trout and rainbow trout (Salmo gairdnerii) were tested in 1946 and brown trout (Salmo trutta) in 1947. The daily dosage rates chosen were 0, 5, 10, and 15 grams of the drug per 100 pounds of fish (0, 11, 22, 33 grams per 100 kilograms).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[93:ROBRAB]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

An epidemic, resulting in the death of large numbers of white crappies (Pomoxis annularis) in McKay Reservoir near Pendleton, Oregon, was found to be due to infection with Cytophaga columnaris, a myxobacterium. Extensive lesions produced by this organism were present on the body and gills of dead and dying fish. Since other epidemics are known to have been produced by C. columnaris, it is suggested that during warm weather this organism may be a frequent cause of mortalities among fish in lakes and possibly in streams.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[102:CCAACO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

This paper presents the results of creel censuses being carried out on four major lakes in Oregon's Cascade Mountains. The study on one lake commenced in 1945 and on the other three in 1946. The fish population of one of the lakes, 130 acres in area, was removed by poison in 1941; all plantings of rainbow trout (Salmo gairdnerii) since that time can be identified in the catch. Two of the lakes of approximately 1,000 acres each are stocked annually with rainbow and eastern brook trout (Salvelinus fontinalis) and the fourth of approximately 3,000 acres is stocked annually with rainbow trout fry produced from an egg-taking station at the lake.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[105:LSIO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

Mortality and survival in four little-exploited fish populations which have been studied by Hart, Hile, and Kennedy are estimated by comparison of the number of individuals of successive ages taken by gill nets. The selectivity of gill nets makes it possible to use only the older fish in their catch for this purpose. For the whitefish of Shakespeare Island Lake in Lake Nipigon, it is possible to demonstrate that a length of 13 inches is the boundary beyond which the effects of selection become inappreciable. In this population mortality rate is very low, varying from 8 percent at age-group XII to 17 percent at XX, and up to 45 percent at XXVII. In Lake Nipigon itself the whitefish died at the rate of 36 percent per year between age-groups XIII and XX; these larger figures presumably were chiefly or entirely the result of commercial fishing. Whitefish of Lake Opeongo died off much more rapidly than either of those cited above, even without fishing, the mortality varying from 41 percent for age-group VII to 59 percent at XIII. The unexploited sauger of Lake Nipigon had mortality rates varying from 26 percent for age-group X to 60 percent for age-group XIV. The oldest of the rock bass of Nebish Lake were dying off rapidly at an annual rate of 66 percent (age-group XI) to 79 percent (age-group XIV). Male rock bass died more rapidly than did females of the same age. In all these unexploited populations mortality rate increased steadily with age over the range in which it could be measured.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[114:MRISLP]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

The experiment was initiated in an attempt to determine the effect resulting from the excision of the adipose fin of lake trout (Cristivomer namaycush). The experimental fish (500 marked and 500 unmarked) taken at random from fish handled during the daily clipping operations were weighed and measured and placed in two troughs allocated for the experiment.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[129:MROGAF]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

In marking experiments with king salmon (Oncorhynchus tshawytscha) fingerlings at Coleman Fisheries Station, California, in 1945 and 1946 half the fingerlings were held over for 6 months after marking. The extent of fin re-formation was studied during these periods. Standards based on the numbers of rays present were used in grading except in the adipose fin where size was the basis.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[132:ROEFOK]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor

摘要:

During the period 1943 to 1946, several combinations of largemouth black bass (Micropterus salmoides) and bluegill (Lepomis macrochirus) were stocked in ponds on the station grounds at Leetown, West Virginia. These ponds were fertilized with 12–5–5, inorganic fertilizer, but when water blooms failed to control the submerged vegetation, sodium arsenite or copper sulfate was occasionally used for this purpose.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1947)77[141:ROVTRO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1949

数据来源: Taylor