摘要:

Three species,Cricotopus bicinctus(Meigen),C.vierriensisGoetghebuer, andC.mackenziensisn.sp., in thebicinctus-group of the genusCricotopusVan der Wulp are now known to occur in the Nearctic. The new species is described from the Fort Simpson area, Northwest Territories, and compared with a closely related species,Cricotopus(s.s.)bicinctus. Most of the differences between the two species are related to the smaller size ofC.mackenziensis.

ISSN:0706-652X    

DOI:10.1139/f77-011

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The morphology of larvalAnisakis simplexin a subsample taken from Atlantic herring,Clupea harengus harengus, in the North Sea (and used in previous in vitro culture experiments) is described, with particular reference to the excretory system.The morphological similarities of these larvae fromC.harengus harengusand Atlantic salmon,Salmo salar, taken in widely separated locations in the North Atlantic suggests thatAnisakislarvae Type 1 isA.simplex. These findings are substantiated by studies on acid phosphatase polymorphism of the larvae and the known geographic ranges of related species. Frequencies of the acid phosphatase phenotypes varied in different sampling areas, suggesting that different populations of larvalA.simplexoccur in fish in the North Atlantic.

ISSN:0706-652X    

DOI:10.1139/f77-012

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Of four highly oligotrophic lakes of the Matamek River System, Quebec, Lac à la Croix containsChaoborus punctipennisandC.trivittatus, Lac GallienneC.americanus, Lac RandinC.americanusandC.trivittatus, and Lac MéchantC.flavicansandC.trivittatus. The instars are all planktonic except instars I–III ofC.trivittatusin Lac à la Croix. All species have a 1-yr life cycle exceptC.americanusin Lac Gallienne which has a 2-yr cycle. The cycles ofC.trivittatusin lacs Randin and Méchant are out of phase by 1 mo or more with those ofC.americanusandC.flavicans, respectively. Seasonal increases in length occurred in most instars except those ofC.punctipennisin Lac à la Croix. Both species in Lac à la Croix made fairly extensive diurnal migrations but in lacs Gallienne and Méchant all species remained near the surface. Intense competition for food is considered the most likely cause of seasonal or spatial separation of instars of similar size in all lakes.

ISSN:0706-652X    

DOI:10.1139/f77-013

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Brook trout (Salvelinus fontinalis) fingerlings were given four injections at weekly intervals of eitherp,p′ -DDT,p,p′ -DDE,p,p′-DDD, orp,p′ -DDMU to yield tissue concentrations of 1–5 mg/kg wet wt. The effect of these treatments on the subsequent dehydrochlorination of an injection of14C-p,p′ -DDT was investigated. The rate of dehydrochlorination of14C-p,p′ -DDT by the trout was not influenced by these treatments and was more highly correlated with factors such as the weight of the fish and their lipid content. Of the compounds injected during the treatment of the fish,p,p′ -DDMU was cleared more rapidly than the others.

ISSN:0706-652X    

DOI:10.1139/f77-014

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Relative growth and survival of offspring from matings of hatchery and wild Deschutes River (Oregon) summer steelhead trout,Salmo gairdneri, were measured to determine if hatchery fish differ genetically from wild fish in traits that can affect the stock–recruitment relationship of wild populations. Sections of four natural streams and a hatchery pond were each stocked with genetically marked (lactate dehydrogenase genotypes) eyed eggs or unfed swim-up fry from each of three matings: hatchery × hatchery (HH), hatchery × wild (HW), and wild × wild (WW). In streams, WW fish had the highest survival and HW fish the highest growth rates when significant differences were found; in the hatchery pond, HH fish had the highest survival and growth rates. The hatchery fish were genetically different from wild fish and when they interbreed with wild fish may reduce the number of smolts produced. Hatchery procedures can be modified to reduce the genetic differences between hatchery and wild fish.

ISSN:0706-652X    

DOI:10.1139/f77-015

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

During studies on inconnu,Stenodus leucichthys, in the Kobuk, Yukon, Koyukuk, Kuskokwim, Holitna, and Chatanika rivers, and the Selawik and Minto Flats areas, 3907 fish were marked. Nine hundred and ten (23.3%) had been recovered by December 31, 1974.Tag return data indicate that tagged inconnu comprise four major populations: Kobuk–Selawik, lower Yukon, Kuskokwim, and Minto Flats.Inconnu undertake rapid downstream postspawning migrations to wintering areas in lower reaches of large rivers (Yukon, Kuskokwim) or slightly brackish inlets (Hotham Inlet, Selawik Lake), then begin slow upstream migration before spring ice breakup, with nonspawning fish travelling to summer feeding areas and spawners migrating to spawning grounds during summer and fall. Minto Flats fish are nonanadromous.Three fish, tagged in the lower Yukon River and recaptured in the Koyukuk River, migrated upstream 1035–1156 km, averaging 13.8 km/day. The longest migration recorded was nearly 1,600 km.

ISSN:0706-652X    

DOI:10.1139/f77-016

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A cell line was grown from fin tissue of lumpfish (Cyclopterus lumpus). The cells were propagated in RTO medium supplemented with NaCl at 18 °C and have a generation time of 108 h. They are fibroblast-like, contain numerous cytoplasmic granules, are susceptible to amphibian virus (LT-1), and have an average chromosome number of 2N = 50.

ISSN:0706-652X    

DOI:10.1139/f77-017

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The incipient lethal level (ILL) of zinc to juvenile Atlantic salmon (Salmo salar) in fresh water at a water hardness of 14 mg/ℓ varies from 150 to 1000 μg/ℓ as a function of season and developmental stage of the fish. The ILL increases from 500 to 1000 μg/ℓ during the 1st yr and decreases to 150 μg/ℓ in the following spring. The more sensitive stage in the salmon's life history, evidenced by decrease of ILL coincides with and is probably related to initial stages of the parr–smolt transfo

ISSN:0706-652X    

DOI:10.1139/f77-018

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Between 1968 and 1971, upriver movement of bass from Lake Simcoe was highly correlated with water temperature and discharge (r = 0.704,P <.001). Vital statistics and growth were similar to lacustrine and riverine stocks at similar latitude. Total annual mortality averaged 0.56 with 65% attributable to angler exploitation, principally in the river. Some 34% (after mortality) river spawners returned upriver in subsequent years. Repeat spawners (65% female) comprised an average 19% of the spawning runs. Most adults moved downriver in late June and July when water temperatures approached 25 °C. Adults remaining in the spawning area experienced water temperatures to 29 °C before emigrating during freshets in July and August. Lake migrants intermingled on shoal areas with lacustrine and possibly other potamodromous stocks each summer.

ISSN:0706-652X    

DOI:10.1139/f77-019

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Dimensions of cleithrum bones from recently caught Atlantic cod (Gadus morhua) were measured and plotted against observed fish lengths to back-calculate cod lengths from cleithra from a ship wrecked in 1865. Mercury levels in the historical bones were approximately the same as those in recent material and showed no increase with fish length, but zinc levels appearto have increased since 1865 and increased with fish length.

ISSN:0706-652X    

DOI:10.1139/f77-020

出版商:NRC Research Press    

年代:1977

数据来源: NRC