摘要:

Population estimates made from observations on the number of sockeye salmon in the various spawning streams of the Skeena River, B.C., during the period 1944–48 are presented. The methods used include a fence count at Babine Lake, the most important spawing area, supplemented by stream counting in the other areas and sample tagging at Lakelse. Estimates made at Babine by the latter methods were compared with the fence counts; the stream count estimates were about one-third of the actual number present, whereas estimates from tagging were about twice the actual.A brief description of the spawning streams of the Skeena is accompanied by a map showing their location. Best estimates of 1946–47 escapements to major spawning areas are: Babine, 480,000; Morice, 70,000; Bear, 42,000; Lakelse, 29,000. These comprise 92 per cent of the total for the river system. The area of the spawning beds used by sockeye in the system is about 100 acres, or of the order of 1.5 square yards per spawning pair. The division of the whole run is approximately 45 per cent to the commercial fishery, 6 per cent to the Indian fishery, and 49 per cent escapement.

ISSN:0706-652X    

DOI:10.1139/f50-029

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Four species of Lake Winnipeg ciscoes (Leucichthys, Coregonidae) were found to differ in several biological characteristics thus supporting their validity as species.L.nigripinnisandtullibeeattained a larger size than eithernipigonorzenithicus. The curves of growth differed for the four species.L.nipigonhad a higher incidence of infection by the pseudophyllidean tapewom,Triaenophorus crassus, than did the other three species. There was no evidence of common relationship among three species between infection and age of host.

ISSN:0706-652X    

DOI:10.1139/f50-030

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Controlled experiments carried out over a three month period on lemon sole (Parophrys vetulus) show that tagging, using the Petersen type of tag, causes significantly more deaths among females than would normally occur, and it is suggested that this is true also for males. The rate of tagging mortality without competition from other types of mortality, extrapolated over a period of one year, was computed to be 41 and 49 per cent for males and females respectively. In neither sex did fish of different sizes die differentially as regards either the number of deaths or the rate at which they occurred. By affixing tags according to three degrees of looseness (0.76 mm., 1.52 mm., and 2.28 mm.) and to different positions on the fish (the nape, below the dorsal fin at the widest dorso-ventral position, and on the caudal peduncle) it was shown that the loosest attachment, and application below the dorsal fin, caused least injury to the fish, as well as the least number of deaths.

ISSN:0706-652X    

DOI:10.1139/f50-031

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Lobsters held in wooden tanks floored with sheets of copper, monel metal, zinc and lead died within 1, 6, 9 and 20 days respectively. Iron, aluminum and stainless steel were non-toxic.

ISSN:0706-652X    

DOI:10.1139/f50-032

出版商:NRC Research Press    

年代:1952

数据来源: NRC

摘要:

Discovery ofTrypanosyllis ingensJohnson off the west coast of Vancouver island is described. The species has hitherto been known from a single specimen collected at Pacific Grove, California, and described some fifty years ago. It is notable for its large size and the possession of a unique form of prostomium.

ISSN:0706-652X    

DOI:10.1139/f50-033

出版商:NRC Research Press    

年代:1952

数据来源: NRC