摘要:

Data were obtained from Cultus Lake giving (a) the number of seaward migrating smolts each year from 1927 to 1944, (b) their mean length and weight, and (c) the number of adults from each smolt migration which returned in the spawning escapement to the lake. These indicate a negative correlation –.5;24, (P < 0.05) between number of smolts and percentage return of adults. By multiple regression this is shown to be related almost wholly to the size of the smolts. With an increase in average weight of smolts from 4 to 10 grams, their average percentage survival is tripled.Smolt size and numbers together account for about 60 per cent of the variation in actual number of adult salmon which arrive at the lake. The residual variability could not be definitely related to available qualitative indices of fishing intensity or duration.

ISSN:0706-652X    

DOI:10.1139/f54-023

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Tagging of 279 spiny dogfish (Squalus acanthias) near St. John's, Newfoundland, July 9 to 23, 1942, gave 5 per cent recaptures: 4 returns in 1942, 5 in 1943 and, apart from 1946, one in each successive year until 1949. Eight recaptures were from Newfoundland, 3 from the Maritime Provinces, 2 from Gloucester, Massachusetts, and one from Virginia.

ISSN:0706-652X    

DOI:10.1139/f54-024

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

As the first part of an investigation of the nutritive value of cod liver, two methods of preparation of cod liver residue were studied, as well as the effect of drum drying the residue, with and without the presence of sodium bisulphite, defatting the dried residue and extracting vitamin B12from the dried residue.It was found that Vandenheuvel's method of preparation of residue produces very good results. The fresh residue could be dried without appreciable loss of vitamin B12activity on a double drum dryer, operated with steam at 20 p.s.i.g. Sodium bisulphite afforded some protection during the drying. The most satisfactory results in defatting were obtained by extraction with dichloroethylene. Concentrates with vitamin B12activity equivalent to 2–4 micrograms per milliliter were produced by extraction of dried, defatted residue with water and evaporationin vacuo.Five different types of residue were prepared for further studies.

ISSN:0706-652X    

DOI:10.1139/f54-025

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Plantings of Atlantic salmon fry were made in the Duffin Creek system in order to determine the survival and distribution of salmon under a variety of stream conditions. Population studies estimated that the three general June plantings resulted in an average survival of 12.7 per cent until the autumn of the first year, 9.2 per cent until the autumn of the second year. High summer temperatures were lethal to the salmon in certain parts of the creek system. Over the balance of the planted part, the greatest mortality occurred soon after plantings when heavy predation by other species of fish occurred. The extent of predation was determined largely by the amount of shelter available to the fry. Suitable shelter for the young salmon was limited generally to gravelly riffle areas where the degree of bottom sedimentation determined the amount of shelter offered. Other stream conditions were of minor or no importance in salmon survival. Further losses of salmon were low once the young salmon had become established in the creek system.

ISSN:0706-652X    

DOI:10.1139/f54-026

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The temperature regime at any point on the bottom over the Scotian Shelf depends upon the geographic location and the depth relative to the structure of the water column. Seasonal variations are observed on any bottom sufficiently shallow to lie within the surface layer. For this reason some areas exhibit maxima in the late fall when the surface layer is deepening. Deeper areas are subjected to non-periodic variations which are related to such factors as slope water incursions and the westward protrusion of Labrador waters. The distribution and variations of temperature over these important fishing grounds are of considerable biological significance.

ISSN:0706-652X    

DOI:10.1139/f54-027

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Miller's method of studying mixing processes is extended to the examination of the characteristics of waters on the Scotian Shelf against a five-pointed grid. The use of the modified T-S theorems and the less rigorous definition of water types make T-S analyses rewarding in this area. Some light is shed upon the mixing processes and movement pattern on the Scotian Shelf.

ISSN:0706-652X    

DOI:10.1139/f54-028

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The plankton material collected by the 1923 expedition of the Canadian Fisheries Research Board was examined with regard to appendicularians (Tunicata). Their occurrence supports the thesis that these animals can serve as current indicators, as suggested by previous authors for the same waters. The distribution of the water of the Labrador current around Newfoundland is traced by the occurrence of oikopleurids, and of their separate age classes, in the hauls. The results agree with the hydrographic data of the expedition and with the distribution of other planktonic groups. Partial disintegration of live appendicularians in response to unfavourable environmental conditions was common, especially where waters of different character mix.

ISSN:0706-652X    

DOI:10.1139/f54-029

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Descriptions are given of the new generaNeopygospio(typeN.laminifera, nov.) andNovobranchus(typeN.pacificus, nov.); of the new speciesNereis(Eunereis)wailesi,Spio butleri,Neopygospio laminifera,Novobranchus pacificus; and of the new varietypacificusofDistylia volutacornis(Montagu). All are from the Pacific coast of Canada. Synonymy is proposed ofLepidonotus caelorusMoore withL. squamatus (Linné), and ofGoniada eximiaEhlers withOphioglycera giganteaVerrill. In addition to the new species and variety, records of three species new to western Canada are presented, and notes on others. Thirteen species and a variety new to eastern Canada are recorded, one of them new to North America.

ISSN:0706-652X    

DOI:10.1139/f54-030

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Silver salmon were captured in traps in Issaquah Creek and its East Fork. The olfactory pits of approximately one-half of the fish were occluded before all of them were displaced to the Issaquah about one mile below the junction of the two streams. The control salmon, unlike those with occluded olfactory pits, showed an excellent ability to repeat their original choice at the stream juncture. This is interpreted to mean that the operated fish were not able to differentiate between the two streams but were distributing themselves in a random fashion. The results, therefore, are in accord with those which would be expected if the fish were relying on their sense of smell in making this choice.

ISSN:0706-652X    

DOI:10.1139/f54-031

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Greatest concentrations of entomostracans at Lakelse Lake in 1949 were in the upper half of a 30-metre column. The copepods were quite uniform in horizontal distribution over the deeper part of the lake while the cladocerans tended to concentrate at the north end. A high abundance of entomostracans occurred between mid-July and mid-October. Sampling at the deepest station only may be sufficient to give an indication of the total incidence ofCyclopssp. in the lake, but a true representation of total abundance of the other entomostracans cannot be obtained by this restricted method of sampling. An apparent decline in the occurrence of entomostracans following 1949 can probably be attributed, in part at least, to a change in efficiency of the collecting nets used.

ISSN:0706-652X    

DOI:10.1139/f54-032

出版商:NRC Research Press    

年代:1954

数据来源: NRC