摘要:

Benthosema glaciale(Reinhardt, 1837) collected off Nova Scotia can be aged using otoliths, one transparent otolith ring being laid down each year. Maximum age attained is at leastyears and maximum length is 68 mm. There is no sexual dimorphism in growth. Part of the population spawns for the first time at age 2 and all at subsequent ages.In the northwestern Atlantic,B.glacialeis abundant in water with temperatures of 4–16 C and is found in temperatures higher than 18 C. Daylight depth range is at least 80–290 fath, the centre of distribution being below 250 fath. At night they are caught from the surface to at least 275 fath with the centre of distribution between 25 and 50 fath, indicating a diurnal vertical migration of over 200 fath for at least part of the population. Older, larger fish are found deeper than young fish at night.

ISSN:0706-652X    

DOI:10.1139/f70-011

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The DNA polymerase of intact trout liver nuclei behaved similarly to that present in mammalian tissues in its mandatory requirement for four deoxynucleoside triphosphates, Mg2+, and DNA primer. It was inhibited by DNase and pyrophosphate in comparatively low concentrations and by RNase and Actinomycin D in comparatively high concentrations. Soluble DNA polymerase was extracted from buffered suspensions of the nuclei by centrifugation at 100,000 g. It possessed properties very similar to those exhibited by the enzyme in intact nuclei. The polymerase activity of intact nuclei was increased by freezing and thawing, and the soluble enzyme was unstable at 30 C and lost most of its activity in 1 day at 0 C. The specific activity of the enzyme was 10–29 picomoles of deoxynucleoside triphosphate incorporated into DNA by 1 mg of protein in 1 hr at 25 C.

ISSN:0706-652X    

DOI:10.1139/f70-012

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

From 1936 to 1965 food content was examined in 17,171 Lake Opeongo lake trout (Salvelinus namaycush). The diet is analysed from the point of view of frequency of occurrence of foods, their weight, feeding activity of trout, size of trout and size of food, and seasonal and annual changes in food habits.In the late 1940's and early 1950's perch,Perca flavescens, largely disappeared from the diet. The lake trout initially turned to lake whitefish,Coregonus clupeaformis, and then to the cisco,Coregonus artedii, introduced into Lake Opeongo in 1948.As a result of these dietary changes lake trout are now heavier and rate of growth has improved. Age and size at maturity is later and there are fewer infertile fish. Egg counts, egg size, and ovary weights are now greater, particularly in the medium-sized lake trout.In the fishery the average weight of individual trout taken has almost doubled. About 25% more of the immature stock is exploited by the recent fishery. The harvest and catchability of lake trout has remained generally constant on a numerical basis but show an improvement on a poundage basis in the more recent years. The possible effects of these changes on the character of the fishery are discussed.

ISSN:0706-652X    

DOI:10.1139/f70-013

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Two kinds ofGasterosteus aculeatus,leiurusandtrachurus, are considered species in several streams and lakes in British Columbia. The two sticklebacks may act as species over a much wider range, but at present there is insufficient evidence for firm conclusions. The data of Miller and Hubbs (Copeia 1969: 52–69, 1969) given as evidence for introgression betweenleiurusandtrachuruson the Pacific coast cannot be taken as well established. Should conclusive data for introgression be forthcoming, it would then seem that the two sticklebacks act as species in places and as subspecies in others. At least along the Pacific coast the pattern of variation found withinGasterosteusis exceedingly complex and cannot be accounted for wholly upon any simple explanation in terms of hybridization betweenleiurusandtrachurus. There is evidence that much of the interpopulation variation is a result of adaptation and natural selection — not introgression. It will in fact require much more investigation before we can proclaim the causes of the variation we see so strikingly inGasterosteus.

ISSN:0706-652X    

DOI:10.1139/f70-014

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Three programs were developed to be used on the CDC 3600 computer at the University of Massachusetts: back-calculation, condition factor, and stomach content. They are written in standard Fortran IV notation, which can be adapted to any computer setup that accepts Fortran IV and has at least the storage capacity listed for each program. Instruction sheets and sample output can be secured from either author.

ISSN:0706-652X    

DOI:10.1139/f70-015

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

A relatively simple and reliable in vitro methodology for fish chromosome study is described. A single cell suspension obtained by trypsinizing ovarian tissue was cultured for 5–7 days at 31 C. The cells were treated with colchicine and hypotonic solutions then fixed in acetic-alcohol fixative. Air-dried preparations were made from these cells and were stained with aceto-orcein.Numerous metaphase plates unmarred by overlapping chromosomes were recovered and high quality karyograms were available for detailed karyotypic analysis. The general similarity of squash and air-dried karyotypes suggests that short-period cell culture preserves natural karyotypes.

ISSN:0706-652X    

DOI:10.1139/f70-016

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Morphometric and meristic variations and ecological differences in 71 Lake Superior lake char,Cristivomer namaycush, from four localities confirmed that the lean lake char,C.n.namaycush, and the siscowet,C.n.siscowet, should be considered subspecies. They differed in four head characters and in mean numbers of anal fin rays and ribs. The siscowet and halfbreed differed in mean number of anal fin rays but not in any morphometric character studied. Differences between the humper and the three other forms were inconclusive.

ISSN:0706-652X    

DOI:10.1139/f70-017

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

In the regulation of water temperatures, it is now possible to improve on the conventional thermostat and the power switch it operates. This may be done through the use of a thermistor and a proportional controller. The latter supplies power to the heater in proportion to the difference between the temperature set on the dial and that measured by the thermistor. The result is exceptionally good temperature control with a minimum of mechanical problems.

ISSN:0706-652X    

DOI:10.1139/f70-018

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Nine specimens of stonecat were taken in the Red River 16 km south of Winnipeg, Man. This is the only known collection of the species from the Hudson Bay drainage. Ecological factors seem to be the main influence confining the species to its present restricted northern locality.

ISSN:0706-652X    

DOI:10.1139/f70-019

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

A use of the relative likelihood function is described. An example is provided to show exact statistical inferences about the parameter for an exponential increase in cell concentration when the concentration is a Poisson random variable.

ISSN:0706-652X    

DOI:10.1139/f70-020

出版商:NRC Research Press    

年代:1970

数据来源: NRC