摘要:

Late stage pre-extrusion larvae have been examined from 37marinus-type and 44mentella-type redfish, obtained from three localities in the Newfoundland area. Examination of 120 larvae from each fish has revealed that a difference exists between the two types, in the relative presence or absence of caudal melanophores in their larvae. The caudal melanophores, when present, are situated near the base of the caudal fin and ventral to the vertebral column. Caudal melanophores were absent in only 2.3% of the larvae frommentella-type parents in contrast to the absence of caudal melanophores in 76.1% of the larvae frommarinus-type parents. When only those larvae having caudal melanophores are considered, larvae frommarinus-type, parents usually have but a single melanophore whereas those frommentella-type parents usually have two caudal melanophores.This difference between larval samples provides evidence of the existence of a real genetic difference betweenmentellaandmarinustypes of redfish in the Northwest Atlantic.

ISSN:0706-652X    

DOI:10.1139/f59-057

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Pacific coast dogfish (Squalus suckleyi) were held 21 days in ice and in refrigerated sea water with and without added chlortetracycline, viable bacterial counts and volatile bases being determined periodically. Viable bacteria increased sharply after about 14 days but the muscle pH values showed little or no increase. No appreciable increase in the total volatile base or trimethylamine content of the muscle was noted until the fish were stored for more than 2 weeks, and then the increases observed were comparatively small.

ISSN:0706-652X    

DOI:10.1139/f59-058

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

In the Gulf of Alaska the chaetognath,Sagitta lyra, was most frequently found in areas where the temperature at 150 m exceeded 6 °C and the salinity exceeded 33‰. Water of this character was mainly associated with a northward intrusion of warm water past the Canadian coast. Comparison of surface gillnet catches of salmon with occurrence ofS.lyrashowed that whenS.lyrawas present in the zooplankton, the salmon catch was small and when it was absent the catches of salmon could be quite large. This change in catch was even observed (on two occasions) on successive days at a station where the physical properties of the water did not change detectably.

ISSN:0706-652X    

DOI:10.1139/f59-059

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The Miramichi is the largest river in northeastern New Brunswick. The watershed covers an area of about 3,500,000 acres. Its waters support commercial fisheries valued at about $1,250,000 in 1952 and 1953. The commercial fisheries are located in the tidal waters which extend inland about 50 miles. The fresh waters extend inland about another 100 miles. Water temperatures range from −1.6 °C in winter to 25 °C in summer and the salinities from 0‰ to 30‰.Thirty-eight families represented by at least 78 species of fishes have been found in the waters of the Miramichi system. Of the species, 53 are marine, 7 anadromous, 1 catadromous, and 17 freshwater.

ISSN:0706-652X    

DOI:10.1139/f59-060

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

A study of the propagation of pink and chum salmon in the central coastal region of British Columbia was made for the years 1947 to 1956.Timing, distribution and movement of the adults and fry are discussed. The effects of temperature, stream discharge, sex ratio and population density were considered in relation to survival of egg to fry. Within the limits observed, temperature, stream discharge and sex ratio were not affecting the population perceptibly, but population density was an important factor. The density of spawners in preceding years also affected the survival in subsequent years.Predation was an important factor in keeping the fry output low: the number of fry consumed was approximately 500,000 during each migration.Ocean survival, including the effect of fishing mortality, ranged from 5.2% down to 0.7% for pink salmon, and from 2.6% to 0.85% for chum salmon. Ocean survival for pink salmon before fishing mortality occurred ranged from 10.8% down to 1.0%.Combination of freshwater and ocean survival rates indicate that a variation up to 190 times the lowest rate recorded is possible.

ISSN:0706-652X    

DOI:10.1139/f59-061

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Excellent production of brook trout (Salvelinus fontinalis) and drainage from a stabilized agricultural area are associated in the streams and ponds of Prince Edward Island. Determinations of phosphorus content of Ellerslie Brook, P.E.I., showed major contributions from commercial fertilizers applied to cultivated land. The inference appears valid that commercial land fertilizers are an important factor in maintaining high trout production, and may enhance oyster production in shallow saltwater inlets at the mouths of the streams.

ISSN:0706-652X    

DOI:10.1139/f59-062

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

1. During the 1920's, plantings of anadromous sockeye fry in small barren lakes tributary to Stuart Lake produced (in addition to smolts) lake-maturing "residual" sockeye dull in colour at maturity. The samples taken contained a large excess of females. 2. The kokanee of Cultus Lake, caught in 1934–36, were all of one year-class and are now believed to have been progeny of Kootenay Lake (West End) kokanee eggs hatched and reared at Cultus Lake, though notintentionallyplanted there. These kokanee were of a bright colour at maturity, like their parent stock, and matured mostly at age 2+.

ISSN:0706-652X    

DOI:10.1139/f59-063

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Coastal cutthroat trout,S.c.clarkiiRichardson, occupy most lakes and streams of coastal British Columbia, including the adjacent islands. Yellowstone cutthroat,S.c.lewisi(Girard), occupy southeastern British Columbia; their range is separated from that of the coastal subspecies by a zone lacking cutthroat trout. A map showing all natural distribution records in the province is presented. From 60 to 146 specimens were examined for distinguishing characters. Spots below the lateral line are more numerous towards the anterior end inS.c.clarkii, but more numerous towards the posterior end inS.c.lewisi. A plot of spot number in selected areas of the body provides almost complete separation of individuals of the two subspecies. Significant differences also occur in certain scale counts and in body and peduncle depth, although these characters overlap considerably between the subspecies. No difference was found in vertebral count.

ISSN:0706-652X    

DOI:10.1139/f59-064

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

By considering data of maximum depth and average depth for 107 lakes, it is suggested that an 'elliptic sinusoid' closely approximates the average shape of lake beds. The elliptic sinusoid is defined as a geometric body whose base is an ellipse such that planes perpendicular to the base ellipse passing through the centre of the latter intersect the surface of the body along troughs of sine curves. The results are capable of practical application.

ISSN:0706-652X    

DOI:10.1139/f59-065

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f59-066

出版商:NRC Research Press    

年代:1959

数据来源: NRC