摘要:

A few hundred to one or two thousand cohoes enter Cultus Lake each year, while the Sweltzer Creek population below it is several times as large. "Jack" (age II) fish usually predominate over older male cohoes at the lake. Spawning in the lake or in tributary streams above yields downstream migrations of some hundreds of fry and, a year later, up to a few thousand yearling smolts. These, on the average, amount to 0.13 per cent of eggs in spawners, or only 3 smolts per female. This does not suffice to maintain the coho run into the lake, which is, therefore, heavily recruited from creek-bred fish each year. There are also a very few age-II seaward migrants, which largely return from the sea the same year. Of yearling smolts marked in 1927, 8 per cent returned to the lake after one and a half year's absence.A large fraction, probably the majority, of yearlings produced in the lake fail to migrate from it and live there into their second or third year of life. They are readily taken by trolling or netting in the autumn of their second year and in the winter and spring of their third. Maturing fish of ages II (males) and III (both sexes) have been taken but they are scarce. For this or other reasons production of young by lake-resident cohoes is negligible, or perhaps altogether lacking.

ISSN:0706-652X    

DOI:10.1139/f53-021

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The colour of 184 humpback whales (Megaptera nodosa), was studied at the Coal Harbour whaling station on Vancouver Island during the summers of 1949, 1950 and 1951. The colour of the throat region, the flippers and the flukes were classified separately, according to the amount of white present in each of these three regions. Humpback whales from the coast of British Columbia differ from those taken at South Georgia, South Africa, New Zealand and Madagascar in being darker in colour. Males are lighter in colour than females, on the average. No definite change in colour occurs with increase in length.

ISSN:0706-652X    

DOI:10.1139/f53-022

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The Arctic char (Salvelinus alpinusLinn.) was studied, in the summers of 1948, 1950 and 1951, about the mouth of the Sylvia Grinnell River, Frobisher Bay, Baffin Island.Otoliths are shown to be reliable age indicators and are used for age determination. Because of deficiencies in the sampling of the fish a calculated growth curve has been constructed. The calculated growth rate is obtained by showing the relationship between otolith width and fish length and expressing it in the equation: log (fish length) = −1.503 + 1.982 log (otolith width). The relationship between otolith ring diameter and fish age is demonstrated, and from these two relationships the lengths of fish at earlier ages are calculated.The char grow very slowly, and reach an age of more than 24 winters. They migrate to the sea in late June and return to fresh water from late July until September. The first movements to the sea probably occur during the fifth, sixth and seventh summers. Sexual maturity in the females is reached at a length of about 45 cm., and at an age of approximately 12 winters. Egg counts of maturing fish averaged 3,589. Only about 33 per cent of the females over 45 cm. were maturing. At least 30 food species were found in the stomachs.Additional growth, fecundity and food studies were made on small samples from George River, Herschel Island and Adlorilik.

ISSN:0706-652X    

DOI:10.1139/f53-023

出版商:NRC Research Press    

年代:1953

数据来源: NRC