摘要:

Charitonetta albeolais a common summer visitant to parts of the interior of British Columbia and is abundant on the coast region in winter. Adults arrive in the interior in advance of the yearlings and the sex ratio in early spring flocks is predominantly male. Later, both age groups associate for a short time, then the paired adults become established on nesting territories. Most of the yearling males, and subsequently the adult males, disappear for six weeks or longer. They eclipse and begin to appear again on certain lakes in August but are not plentiful until late September or early October. The yearling females remain on the breeding grounds in flocks throughout the summer. Courtship which is observed first on the coast in March reaches its greatest intensity on the interior lakes in April. Males vigorously defend their nesting territories. Eggs are laid in May and by the last week of June most of the young have appeared. Breeding females leave their broods in order to moult before the young have reached the flying stage and associate with flocks of yearling females that have gathered on certain waters where food is abundant. At this time all are excessively wary. In the interior aquatic insects are the chief food of downy young, adolescents, and adults. On certain lakes amphipods and molluscs are important foods. Fishes, where available, form a minor part of the diet. Seeds of aquatic plants are the main vegetable food except on Okanagan Lake where a larger amount of other plant material is consumed. On salt water, crustaceans and molluscs are first and small fishes, second in importance. The buffle-head is highly regarded as an object of beauty. In the interior it is of economic value as food but is not held in esteem on coast waters. No evidence of it eating commercially valuable fishes was obtained and its consumption of salmon eggs, noted on coast streams, does not reach significant proportions.

ISSN:1923-4287    

DOI:10.1139/cjr42d-012

出版商:NRC Research Press    

年代:1942

数据来源: NRC

摘要:

Proteus hydrophilushas been isolated from and shown to be the probable cause of "ulcer disease" of hatchery reared brook trout.Cultures ofProteus hydrophilusisolated from "red sore" diseased pike, "ulcer" diseased trout, "red leg" diseased frogs and from lake water are shown to be indistinguishable by cultural and biochemical reactions.Proteus hydrophilusinfections are shown to be transmissible by water.

ISSN:1923-4287    

DOI:10.1139/cjr42d-013

出版商:NRC Research Press    

年代:1942

数据来源: NRC

摘要:

Data are presented on the percentage of liver and intestines in the fish, percentage of oil in body, liver, intestines, and offal and the vitamins A and D potency, iodine value, and percentage of unsaponifiable matter in these oils of shad and mackerel.

ISSN:1923-4287    

DOI:10.1139/cjr42d-014

出版商:NRC Research Press    

年代:1942

数据来源: NRC

摘要:

The life cycle ofPseudobilharziella querquedulaeMcLeod, 1937 has been completed experimentally and the relationship of the adult toCercaria physellaTalbot, 1936 has been definitely established. The female of the species and the eggs were recovered and are described for the first time. A report is given on the exposure of a number of species of molluscs to the miracidia of this schistosome and notes on the life cycle and adult stage ofCercaria dermolestesMcLeod, 1940 are included. A case of hypersensitiveness in man to the proteins of schistosome cercariae is reported.

ISSN:1923-4287    

DOI:10.1139/cjr42d-015

出版商:NRC Research Press    

年代:1942

数据来源: NRC