摘要:

New and previously published records are listed for 28 species of freshwater fishes in tributaries of the Mackenzie River in northern British Columbia. Distribution patterns are discussed for all species reaching the continental divide at the Peace River headwaters; some are restricted to one or other side, but 17 species are common to the Peace and Fraser Rivers, suggesting that mountain ranges have served as a check but not an insurmountable obstacle to postglacial expansion. Five species indigenous to the Pacific slope—Catostomus macrocheilus,Richardsonius balteatus,Ptychocheilus oregonense,Mylocheilus caurinum, andCottus asper—have evidently penetrated to the Peace River in comparatively recent times. Three species—the flathead chubPlatygobio gracilis, the trout-perchPercopsis omiscomaycus, and the spoon-head sculpinCottus ricei—have not previously been recorded from the province. Evidence is presented that subspecific distinctions are invalid inCouesius plumbeus(Agassiz) andLota lota(Linnaeus).Coregonus coulieriandHybognathus hankinsoniare reported for the first time from the Mackenzie drainage.

ISSN:0706-652X    

DOI:10.1139/f56-044

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The variation of the efficiency of acetone as an extractant of fats from biological materials has been studied. The moisture content of the acetone was found to be the dominating factor. Refluxing time, as well as the ratio of solvent to sample, have been found to be of minor importance. A rapid, precise analytical method of fat determination based on these observations has been developed.

ISSN:0706-652X    

DOI:10.1139/f56-045

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

For the present macroscopic study over 1,000 female speckled trout from the Laurentide Park in Quebec have been examined. Of this number, 747 specimens received special attention. In ovaries of adult trout 3 types of eggs were found:recruitment stock(Classa),maturing eggs(Classb) andatretic eggs(Classc). In the process of maturation, the number of eggs of Classbprogressively decreases due to atresia, but their diameter becomes greater. Comparisons of fecundity between different trout populations should be made only when eggs are nearly mature. The diameter of ripe eggs just previous to spawning, preserved in formalin, varied from 3.8 to 4.8 mm. There is a direct relation between the number of ripe eggs and the size of the fish: the extreme numbers of eggs were 90 and 4,800 eggs, and the extremes of fork lengths of females were 6 and 22 inches. The fecundity is greater among fish from lakes richer in food. A simplified method of determining the number of eggs in ovaries was devised. The maturity of females was determined by a 7-digit system. The colour of flesh was classified by a 6-digit system.

ISSN:0706-652X    

DOI:10.1139/f56-046

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Arctic char (Salvelinus alpinusL.) from the commercial sea run were sampled at five stations in northern Labrador. Otoliths were used for age determination. In the southern part of the range—Adlatok and Nain—commercial size is reached at 6 years and at places farther north in 7 years. There is also a tendency for older fish to occur as one proceeds north.Age, weight, and length frequencies as well as their relationship to one another were determined.Vertebral counts indicate little, if any, intermingling of populations between: Adlatok and Nain, Okkak Bay and Hebron, Adlatok and Ramah, Nain and Hebron. Fin ray counts conform with the vertebral results but indicate no significant difference between Adlatok and Nain or Nain and Okkak Bay fish.Variations in flesh colour from white to deep red is a distinct characteristic of Arctic char in northern Labrador; flesh colour has a distinct bearing on the market value of the fish.Principal food items included capelin, launce, young of mailed sculpin, Amphipoda, and Euphausiacea.

ISSN:0706-652X    

DOI:10.1139/f56-047

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Offensive "bilgy" odours develop when fish are stored in contact with slime-soaked wooden surfaces. Anaerobic bacteria develop in the slime layer between the surfaces of the fish and the wood.The muscle of bilgy fish has a higher hydrogen sulphide and a lower mercaptan content than that of similar fish spoiling in ice but not in contact with wood. The trimethylamine and volatile acid values are usually, but not consistently, high in bilgy fish.In the observations described in this paper, the fillets of fish stored in contact with dirty pen boards acquired a distinct bilgy odour when the anaerobic bacteria on the skin exceeded 106 per cm.2, at which point the hydrogen sulphide content of the muscle was 0.05 mg. or more per 100 g. of fish.

ISSN:0706-652X    

DOI:10.1139/f56-048

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Annually, large amounts of cod and haddock viscera (minus livers) are discarded by the fishing industry. The chemical composition of this offal makes it a possible raw material for production of additives to animal feeds. Various processes that would lead to a method of production of such preparations were investigated. Autolysis of fresh viscera in the presence of sodium nitrite as a preservative was found most attractive. Optimum conditions for this process were established and various methods of drying these autolysates were investigated.

ISSN:0706-652X    

DOI:10.1139/f56-049

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f56-050

出版商:NRC Research Press    

年代:1956

数据来源: NRC