摘要:

Seasonal studies of bottom foods were made in Waddell Creek Lagoon in 1932, 1933, and 1934. Quantitative samples were taken both with an Ekman dredge and a square-foot box. The numbers of organisms per square meter and pounds of food per acre are based on recalculations of results obtained from the unit areas sampled.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[178:QAQOOF]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor

摘要:

Three of the major problems connected with rainbow trout production and management were studied at Paul Lake, British Columbia: (1) what quantity of fish can be produced in a given body of water, (2) how big a crop can be removed and still allow a sustained yield, (3) how great a financial expenditure to increase production may be justified. The investigation covered a period from 1931 through 1936 in which a consistent stocking policy requiring the planting of 200,000 one-inch fry was carried out. The data show that the lake was capable of producing about 10 pounds of trout per acre and that this amount is being maintained under the policy outlined. The mortality amounted to about 95 per cent, providing a 5 per cent yield to the fishermen. The cost of the stocking operations was judged to be commensurate with the return to the people of the Kamloops District. It is suggested that intensive management of this type should be instituted only after adequate surveys have been made of individual bodies of water.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[187:TPORTA]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[192:POAESO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor

摘要:

A study was made of the minimum concentration of oxygen in the water necessary to maintain sockeye and chinook salmon in normal condition. It was found that when the oxygen content of the water was reduced to 3.5 p.p.m. salmon showed definite signs of distress; a reduction below 3.0 p.p.m. caused the death of some fish; a reduction below 2.5 p.p.m. brought about the asphyxiation of most of the fish in a short time. Considerable individual variation was found, some fish not dying until the oxygen concentration had dropped to 1.2 p.p.m. Some notes also are presented concerning the reaction of suckers and carp to a diminished oxygen supply.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[197:EOADOS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor

摘要:

An analysis is presented of the food of 170 specimens of the young of the common bullhead, Ameiurus nebulosus nebulosus (LeSueur), taken at intervals from June 21 to October 10, 1938, in quiet coves of Cayuga Lake, Ithaca, New York. A large variety of organisms were utilized for food. The main staples were Crustacea (approximately 60 per cent) and Diptera (approximately 25 per cent). Almost all of the Diptera were chironomid larvae, while 80 per cent of the Crustacea were ostracods and cladocerans. Considerable variation in the length attained by the common bullheads was noted in the collections taken after the middle of July. By October 10 the largest specimen was more than twice the length of the smallest. While the mean total length does not exceed 3 inches at the end of the first growing season, some individuals may reach a total length of nearly 4 inches.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[205:TFAGOT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor

摘要:

An electrical method of collecting fish has been developed which appears to be successful in streams up to 20 feet in width, and depths not greater than can be waded. Fish stunned, and then collected with a scap net, recover when placed in fresh water, so that almost none die as a result of the shock. The method has been tested in hard and soft water and under a variety of stream conditions. Fish may be removed from areas where brush, boulders and other obstructions prohibit seining. Because the fish turn with the light-colored ventral side up when stunned they become more visible than when only the dorsal surface is exposed to the view. The method is effective for fish large enough to be seen easily when stunned, that is, fish 3 inches or more in length.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[210:AEMOCF]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor

摘要:

The history of the Pyramid Lake (Nevada) cutthroat trout (Salmo henshawi Gill and Jordan) fishery, conducted by reservation Indians, shows a rapid decline in the catch within the last few years. While the Indian is blamed for overfishing, the white man's demand for trout, the dams and diversions that he built along the Truckee River where the trout have spawned, the pollutants that he has dumped into the river, the spawn that he has taken, the competing species of fish that he has introduced, and principally the large amounts of water that he has diverted to another watershed, have led to a condition which has prevented the trout from reproducing its kind. The revival of the fishery is made doubtful by an agreement concerning the use of the Truckee River's flow, the expense of hatching and rearing a stock of the Pyramid Lake trout (not to mention the questionable availability of its eggs), and inadequate regulation of the fishery. Thus, the Pyramid Lake cutthroat trout fishery appears to be doomed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[216:TDOTPL]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor

摘要:

Renewed activity in the placer gold mining country of the Pacific Coast States has raised the question of how much harm silt does to salmon and trout. The effect silt may have on migrating adult fish, on the selection of spawning places, and on the survival of fish food, is discussed. The conclusion is drawn that silt, whether from placer mining or natural erosion, is harmful to salmon and trout if it is heavy enough to form a layer on the stream bottom or if it persists during periods between floods.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[225:PMSAIR]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor

摘要:

A method of measuring the areas of stream sections and a method of removing the fish therefrom are described. Cresol is used to render the fish helpless, and a formula is given for calculating the amount necessary for a treatment. The advantage of the new method lies in the fact that the fish can be removed from the stream, examined, and returned to the stream unharmed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[231:AMOETN]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor

摘要:

From 1930 until 1939 a study of the natural propagation of the pink salmon (Oncorhynchus gorbuscha) has been carried out at McClinton Creek, a tributary to Masset Inlet on the Queen Charlotte Islands in northern British Columbia. This stream, approximately 4 miles in length, possesses a good spawning bed, and has always had a considerable run of pink salmon. Specially constructed fences were used to assess and examine the adults migrating upstream and the fry returning to the sea. The production of fry from five spawnings has varied from 6.9 to 23.8 per cent of the possible egg deposition, i.e., the number of eggs calculated to be contained in all the females released above the weir. The loss of 76.2 to 93.1 per cent may be due to many factors, among the most important of which are the climatic conditions as they affect the water height, velocity, etc., during the stages from spawning to fry migration, and predators as they prey upon the adult salmon, the eggs and the fry. It is suggested that the number of fish or the number of eggs deposited may have an effect on the production efficiency. Data on the marine portion of the life history will not be discussed until further information is obtained on the migrations in the sea.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1939)69[237:ASOTNP]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1940

数据来源: Taylor