摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f55-044

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

Fluctuations in total landings and in catch per boat have characterized the Digby scallop fishery since it began in 1920. An analysis of records of the fishery indicates that, although changes in fishing methods have been partly responsible for early changes in catch, their influence in recent years has been small and changes in abundance have been primarily responsible for fluctuations in the fishery since it reached its full development in the mid-thirties.Changes in abundance are assessed from analyses of catch records, special "census-fishing" techniques, submarine photography and marking experiments. Estimates from the different methods correspond.Scallops are recruited into the catchable population as six-year-old year-classes. Abundance is high when these recruited year-classes are strong, but is low when they are weak. Abundance in any year is correlated with water temperature six years previously. Both abundance and the strength of individual year-classes are correlated with water temperatures which prevailed at the time the scallops were present as pelagic larvae.It is concluded that changes in the abundance of the catchable scallop stocks result from the combined action of temperature and circulation on the pelagic larvae. Low temperatures retard larval development, and are indicative of great exchange of the water in the Bay of Fundy with outside water masses. This apparently leads to heavy losses of the larvae from the Bay, poor sets on the parent beds, weak year-classes and low abundance of the catchable stocks of six years later. High temperatures speed larval development and are indicative of a closed Fundy circulation which holds the larvae in the vicinity of the parent beds. This leads to good sets, strong year-classes and high abundance of the catchable stocks six years later.

ISSN:0706-652X    

DOI:10.1139/f55-045

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

Collections of planktonic copepods of Ungava Bay and central Hudson Strait were made during late June, July and August of 1947, 1949 and 1950. The following 22 species have been identified:Calanus finmarchicus,C.hyperboreus,C.helgolandicus,Pseudocalanus minutus,Microcalanus pygmaeus,Gaidius tenuispinus,Aetideopsis rostrata,Pareuchaeta norvegica,P.glacialis,Eurytemora americana,Metridia longa,Pleuromamma robusta,Heterorhabdus norvegicus,Acartia longiremis,A.bifilosa,Oithona similis,Oncaea borealis,Cyclopina gracilis,C.schneideri,Monstrilla dubia,M.helgolandicaandM.canadensis. The last 5 species have not previously been recorded from the western North Atlantic. Males ofCyclopina Schneideriare described for the first time. The two most abundant species,Calanus finmarchicusandPseudocalanus minutus, have one generation a year. A small part of the population ofPseudocalanus minutusbreeds a second time in the autumn. The next most common species,Acartia longiremisandOithona similis, probably breed and spawn in July. The population dynamics of all the species are discussed.

ISSN:0706-652X    

DOI:10.1139/f55-046

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

A collection of 26 species of echinoderms, collected between 1947 and 1952 by theCalanusexpeditions in Ungava Bay, eastern Hudson Strait, Frobisher Bay and Cumberland Sound, is described. Included are one crinoid, 10 asteroids, 9 ophiurans, one echinoid and 5 holothurians; of which 6 asteroids, 5 ophiurans and 4 holothurians are new records for the collection areas.

ISSN:0706-652X    

DOI:10.1139/f55-047

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

During the summers of 1953 and 1954 the effects of forced activity on two blood constituents were investigated in seven species of fresh-water fishes, representing six families. The fish were hatchery-raised or captured from lakes in the southern Okanagan Valley, and the experiments were carried out in the Summerland Trout Hatchery, Summerland, B.C. Following forced exercise for 15 minutes in water at 11.5 °C. the hemoglobin level increased significantly in only one species and the lactic acid increased significantly in all species. There appears to be a correlation between the average value of lactic acid following exercise and the activity of the fish, and also with the position of the species with respect to summer water temperature.

ISSN:0706-652X    

DOI:10.1139/f55-048

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

Burbot are common in Lake Winnipeg; 886 were taken as a sample. Trap-net and otter-trawl catches are more representative of the population than gill-net catches. A significant difference in length-weight relationship exists between two localities. Ages were determined from otoliths. Heavier exploitation in the northern part of the lake probably accelerated the growth rate. Age-6 burbot there weighed 3.4 pounds compared with 2.6 pounds in the southern part. Spawning begins about January 31 and lasts 3 weeks. The smaller burbot feed mainly on insect larvae, the larger burbot on fish and crayfish.

ISSN:0706-652X    

DOI:10.1139/f55-049

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f55-050

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f55-051

出版商:NRC Research Press    

年代:1955

数据来源: NRC