摘要:

Four species of fish found in Ontario streams can be divided into two distinct groups on the basis of habitat and associated fauna.Salvelinus fontinalis(Mitchill) andCottus bairdiGirard are found associated in cool source waters whereasAmbloplites rupestris(Rafinesque) andMicropterus dolomieuiLacépède occur together in warmer downstream waters. The latter group has more associated species of fish than the former. Some invertebrates such as certain stonefly and mayfly nymphs occur frequently with fish of one group and rarely with fish of the other group. They may be useful as indicators of waters likely to be inhabited by or suitable for the species of fish with which they are frequently associated.

ISSN:0706-652X    

DOI:10.1139/f59-015

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The oxygen consumption at a steady rate of activity maintained by a mild electric stimulus was measured forSalvelinus fontinalis(Mitchill),Catostomus commersoni(Lacepede),Ameiurus nebulosusLeSueur,Cyprinus carpio(Linnaeus) andCarassius auratus(Linnaeus) in the presence of various combinations of oxygen and carbon dioxide. At a given level of oxygen the logarithm of the rate of oxygen consumption decreases linearly with the concentration of carbon dioxide. The linear relation so found is characteristic of a given species and the sensitivity to carbon dioxide decreases with increasing acclimation temperature. The oxygen concentration determines the level of active oxygen consumption in the absence of carbon dioxide and when the concentration approaches the lower lethal limit the effect of the addition of carbon dioxide is enhanced. The data found for these species for active metabolism was combined with data in the literature for resting metabolism to give estimates of the metabolism available for activity. The respiratory sensitivities of the four species were further compared by considering the estimated combinations of oxygen and carbon dioxide required to bring about asphyxiation in both flowing water and sealed containers. The ability of the blood of the fish to take up oxygen in the presence of carbon dioxide shows no direct relation to the ability of the fish to transport oxygen to the external medium under similar circumstances.

ISSN:0706-652X    

DOI:10.1139/f59-016

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The incidence of nematodes in fillets of Atlantic cod (Gadus callarias) was determined in 1957 in four areas within 10 miles of Lockeport, N.S., and in six areas in the southwestern Gulf of St. Lawrence. About 1,500 cod, mostly between 1 and 6 years of age, were examined. All nematodes examined (517) were larvae. About 97% belonged to the genusPorrocaecum; the remainder appeared to belong to the genusAnisakis. In all areas there was a progressive increase in incidence with increasing age of cod. In age-groups IV and V usually more than 70% of the cod were infected. Considerable local variation in incidence was observed in the Lockeport region. Cod were more heavily infected in inshore than in offshore waters. The samples from the Gulf of St. Lawrence showed less geographic variation in incidence than the Lockeport samples. The incidence in cod from the Magdalen Islands was noticeably lower than that in cod from the New Brunswick shore. Cod in the Gulf of St. Lawrence were infected to about the same extent as those from the offshore areas near Lockeport. The relation between local variations in incidence and the distribution of seals is briefly discussed.

ISSN:0706-652X    

DOI:10.1139/f59-017

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

A study has been made of the landed quality (i.e. the quality at the time of discharge from the vessels) of trawler-caught, gutted and iced market cod and large haddock. The rate of deterioration, as indicated by the rise in TMA values, varies with the time of the year. Poorer quality fish are landed during the colder months of November and December and also during the warmer summer months of June, July, and August. The best quality fish are landed during the months of February, March, April, May and September.This seasonal spoilage pattern is similar for cod and for haddock and has been observed in the landed quality of the fish from eight individual trawlers over a period of 13 months.Some of the probable factors that bring about this seasonal pattern in the spoilage rate of these fish are discussed.

ISSN:0706-652X    

DOI:10.1139/f59-018

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The absolute changes in fat, protein, water and free and esterified cholesterol for the entire body of standard male and female sockeye salmon (Oncorhynchus nerka) during the Fraser River spawning migration are discussed.The data were obtained for twelve groups of males and twelve groups of females, totalling 216 fish. The fish were caught at three locations: before entering the river, 250 miles up the river, and at one of the spawning grounds 715 miles from the first sampling station.

ISSN:0706-652X    

DOI:10.1139/f59-019

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f59-020

出版商:NRC Research Press    

年代:1959

数据来源: NRC