摘要:

Fry from Atlantic salmon taken in Chaleur bay, near the mouth of the Restigouche river, N.B., where the salmon enter early in the summer and mainly as two-sea-year and three-sea-year fish, were planted in 1932 in the East branch (without salmon) of the Apple river at the head of the bay of Fundy. In this region the local salmon enter only in the autumn and nearly all as one-sea-year fish (grilse). The Restigouche fish as parr grew more rapidly than the local fish, corresponding with the less crowded conditions in the East branch. The smolts were marked by removal of the adipose fin when descending to the sea in 1934. Their descent occurred from May 12 to June 20, being markedly accelerated by rainfall. Traps were placed on both branches in 1935, giving in the autumn 92 marked grilse entering the East branch and 6 the South. The traps in 1936 gave in the autumn, 5 marked two-sea-year salmon entering the East branch and 1 the South. No difference in appearance or behaviour was observable between these and the local salmon of the South branch.

ISSN:0706-652X    

DOI:10.1139/f38-001

出版商:NRC Research Press    

年代:1938

数据来源: NRC

摘要:

Of the various kinds of error which arise in quantitative plankton investigations, those involved in the process of enumeration of a collection are ordinarily smallest in magnitude, though fractioning may introduce an extra sampling error, particularly when not done volumetrically.More serious are the possibilities of error in the collection of the plankters from the lake. Traps are in general more accurate than nets, but the latter are more convenient, and when made of no. 10 silk are reliable quantitative collectors of the larger organisms. The more usual no. 20 silk is very variable in efficiency. Both nets and traps appear to suffer from the ability of some plankters to see and avoid them, by day. The sampling error of a collection, considered as representing the part of the lake near which it was taken, is such as to make a single collection, containing only a moderate number of individuals, of little value in determining abundance of a species.On Cultus lake, collections taken at a single central station will indicate the average abundance of the pelagic plankton almost as precisely as would the same number of collections taken at various points throughout the whole pelagic region.

ISSN:0706-652X    

DOI:10.1139/f38-002

出版商:NRC Research Press    

年代:1938

数据来源: NRC

摘要:

Intermittently over a 13 year period the net plankton of Cultus lake has been sampled, at a central representative station. Net plankton was not particularly rich in common species. Of the entomostracans important as fish food, only four occurred. Seasonal distribution of the various species is of two principal kinds: unimodal, with one peak of abundance in late spring or summer—various green algae, Protozoa, Rotatoria, Cladocera andEpischura; and bimodal with peaks in early spring and in autumn—diatoms, mostly Rotatoria andCyclops. Among bimodal species the spring maximum is ordinarily the greater. Marked differences in abundance of a plankter occur from year to year and affect both the maximal numbers attained and duration of time of proliferation. The available data do not show these annual changes to be cyclic and no definite correlation with environmental conditions has been made. The total nitrogen content of net plankton varied from 2 to 10 mg. per l. in 1932, the dry weight from 30 to 210 mg.

ISSN:0706-652X    

DOI:10.1139/f38-003

出版商:NRC Research Press    

年代:1938

数据来源: NRC

摘要:

Nestlings on the Margaree river, Nova Scotia, are fed young salmon and trout only, whose average size increases with that of the bird, indicating selection by the parents. The proportion of trout (Salvelinus fontinalis) to young salmon (Salmo salar) in the food of the adults varies directly with the height of the water.

ISSN:0706-652X    

DOI:10.1139/f38-004

出版商:NRC Research Press    

年代:1938

数据来源: NRC

摘要:

Paphia bifurcata: a new molluscan species from Ladysmith harbour, B.C. Distinguishing characters chiefly: shell shape; relatively shallow, rounded pallial sinus; and siphons separated at tips.

ISSN:0706-652X    

DOI:10.1139/f38-005

出版商:NRC Research Press    

年代:1938

数据来源: NRC

摘要:

Carotene, xanthophyll and fucoxanthin were found in commercial British Columbia pilchard oil, but only the two former in oil from canned fish. Heating commercial oil as in canning did not destroy the fucoxanthin, indicating its absence in the parts of fish canned.

ISSN:0706-652X    

DOI:10.1139/f38-006

出版商:NRC Research Press    

年代:1938

数据来源: NRC

摘要:

Pilchard oil contains approximately 23% saturated fatty acids and over 15% highly unsaturated C24acids. Unsaturated C16, C18, C20and C24acids are also present in considerable amount.

ISSN:0706-652X    

DOI:10.1139/f38-007

出版商:NRC Research Press    

年代:1938

数据来源: NRC