摘要:

A new method of increasing the capacity of a trout hatchery has been developed through the use of small circular tanks. These tanks are superimposed and fastened independently by means of a swivel arrangement, to a vertical post. The use of this method for incubating trout eggs and rearing fry has increased by four times the potential capacity of a hatchery at Saint Faustin, Quebec, where the new method was developed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1940)70[430:AMOITC]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor

摘要:

The yellow perch, Perca flavescens (Mitchill), of Costello Lake, Algonquin Park, Ontario, were sampled regularly from June to September, 1937, by means of minnow traps. From this 89-acre lake about 750 individuals were taken for an analysis of growth and feeding habits.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1940)70[436:SVISCA]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor

摘要:

Costiasis, or the disease produced by the flagellated protozoan ectoparasite, Costia necatrix, is of considerable importance in the artificial propagation of both warm- and cold-water fishes. In spite of its importance, costiasis seldom is accurately diagnosed probably because of the extremely small size and sedentary nature of the causative organism. A general resume of the specific diagnostic characteristics, pathology, and recommended measures for the prevention and control of Costia necatrix are presented. The application of available information concerning the parasite may eliminate effectively the losses of fish in hatcheries occasioned by it.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1940)70[441:NOCN]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor

摘要:

Intensive creel censuses served as the chief basis for estimates of the effectiveness of plantings of marked legal-sized brook trout, brown trout and rainbow trout at various seasons over a period of from 1 to 3 years in sections of five public streams and in two private streams. Similar data are presented for plantings of rainbow trout in five lakes. Returns from fall planting in streams never exceeded 5.3 per cent; spring and open-season plantings resulted in the recovery by anglers of from 4.9 to 61.9 per cent of the fish released. Fall plantings of rainbow trout in lakes yielded returns up to 66 per cent. Plantings of from 100 to 160 trout per mile of stream averaging 50 feet in width yielded higher percentage returns than did plantings of larger numbers of fish, benefited relatively more anglers, and did not stimulate the catch of native fish. The increase in the catch per hour and the percentage of hatchery fish in the total catch appeared to be inversely proportional to the density of the native population of the species stocked and directly proportional to the number of fish planted. The percentage of the total catch contributed by plantings of moderate numbers of trout in the spring or during the season varied from 1.8 to 30.4. It is concluded that in northern Michigan streams, major dependence for good fishing must be placed on the native or “wild” stock. Rainbow trout and brown trout were caught for at least 8 weeks following planting, although the majority was removed by the end of 4 weeks; few if any brook trout were taken after 4 weeks. Very few planted trout survived one or more winters even in private streams not subject to intensive angling. Most of the trout were taken within 5 miles of the point of release and usually downstream; of the three species, rainbow trout migrated most extensively. From 5.7 to 20.6 per cent of the fisherman-day records showed the capture of marked trout. Apparently as many anglers benefited frown “spot” plantings as from wider distribution by boat. Control experiments proved that jaw-tagging and fin-clipping provided effective methods of tracing fish during the period of investigation and that mortality and the effect on growth of either method were negligible.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1940)70[446:RFPOMT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor

摘要:

A set of three large siphon tubes has been installed on the lower St. Francis River in Arkansas, which pass the normal flow of the river. They operate with a negative pressure equivalent to from 18 to 26 inches of mercury. Experiments with fish held under negative pressure in aquaria for the length of time required to pass through the tubes have been conducted and some species of fish show serious injury. Those that are physostomous are more able to make the sudden change or adjustment in the swim bladder necessary when passing through the tubes, while physoclistous fish are unable to make the sudden adjustment and suffer hemorrhage in the circulatory system and many die. There is need for close cooperation between engineers and fishery administrators in designing and constructing devices that are apt to affect fish life in public waters.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1940)70[469:TEOHVO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor

摘要:

Croakers of varying ages and with approximately an equal distribution of the sexes were studied to determine gonad development. Data gathered indicate that males mature earlier than females. The smallest male to reach sexual maturity was 24 centimeters long, whereas smallest ripe female was 27.5 centimeters long, total length. The ages of these fish, as indicated by scale examinations, were 2 and 3 years, respectively. All fish 3 years or older had ripening gonads. The fish studied were collected by random sampling, in which the ratio of males to females in the areas changed from 50:50 in June to a ratio of approximately 35:65 during early August. This evidence, further supported by records of ocean catches, indicates that males begin their spawning migrations out of the bay earlier than females. At the time of departure whether males or females, the gonads have reached comparatively complete maturity. Evidence based upon tagging, gonad development, and samples from commercial catches, shows that sexually mature croakers leave bay waters largely during the month of August, and that virtually all fish have departed by September 15, the greatest wave of migration taking place during the first week in August. Sexually mature croakers return to the Chesapeake Bay waters during late spring.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1940)70[475:SDOTCM]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor

摘要:

The fish inspection system of the State of Minnesota was instituted in 1932 by the Department of Agriculture, Dairy and Food. It was created as a service to fishermen to determine if their catches were sufficiently free from parasitic infestation by the tapeworm Triaenophorus robustus to allow them to pass market inspection by the U. S. Food and Drug Administration. The service, which also regulates and certifies as to quality of fish, now covers all herring and tullibees produced for commerce by Minnesota fishermen.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1940)70[483:IOFBTS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1941.10493086

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1941.10493087

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor

ISSN:0002-8487    

DOI:10.1577/00028487.1941.10493088

出版商:Taylor & Francis Group    

年代:1941

数据来源: Taylor