摘要:

The rates of oxygen consumption ofEuphausia pacificaHansen,Thysanoëssa spiniferaHolmes, andSergestes similisHansen at 1 atm were compared with the rates at 16–50 atm. Differences were not significant, indicating little effect of pressure on respiratory rate. Apparently temperature has more influence than pressure on the respiration of these species during their diel vertical migrations.

ISSN:0706-652X    

DOI:10.1139/f68-116

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Selected muscle proteins were examined in artificially reared redside shiners,Richardsonius balteatus, peamouth chubs,Mylocheilus caurinum, and in their F1and backcross hybrids to determine if they would be useful in identifying suspected natural hybrids. In reference to the proteins studied,Mylocheiluspossesses a single zone designated "3";Richardsoniusalso possesses a single zone designated "1," but of slower mobility. Artificially reared F1hybrids possess, in addition to both parental zones, a unique zone designated "2" which was assumed to be composed of components of zones 1 and 3. Some naturally occurring individuals suspected of being hybrids on the basis of morphological characters possessed a pattern identical to that of the experimentally produced F1hybrid (zones 1, 2, 3). Other suspected hybrids possessed either zones 1 and 2 or zones 2 and 3. These types of pattern corresponded to some of those produced by backcrosses toRichardsoniusandMylocheilus, respectively.The presence of both parental protein zones in the F1hybrid indicates that each polypeptide can be synthesized when only half the alleles of each parent is present. This characteristic of codominance can be useful in identifying suspected hybrid offspring of parents having different protein zones.Evidence is presented which supports the hypothesis that the proteins in question are genetically controlled by two loci, A and B, each of which exists in two allelic forms.

ISSN:0706-652X    

DOI:10.1139/f68-117

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The isozyme patterns of lactate dehydrogenase (LDH) were examined in three species of trout using electrophoresis in polyacrylamide gel slabs. Each pattern was species specific and contained 15 isozymes of LDH, but a hybrid trout had at least 27 LDH isozymes. Tissue specificity of these isozymes was low except for skeletal muscle. These results suggest that LDH isozyme patterns could be used for taxonomic and diagnostic purposes.

ISSN:0706-652X    

DOI:10.1139/f68-118

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Stable strontium is fed to fish in a Sr-rich, Ca-free synthetic food for a short period of time. Subsequent identification by flame emission photometry can be made using a single scale from a marked fish. One year after marking, scales from marked fish contain approximately 10 times as much Sr as those from control fish. There is no evidence of damage to fish due to their elevated Sr content.

ISSN:0706-652X    

DOI:10.1139/f68-119

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The striated adductor muscle of the scallopPlacopecten magellanicusis described. The fusiform uninucleate cells contain one fibril which is divided into A and I zones, and has Z and H bands. The A zone is 1.9 μ long, and in this zone apart from the H band about eight actin filaments surround each myosin filament. A sarcoplasmic reticulum envelops the fibril. Tubules of this reticulum are mainly oriented longitudinally and swellings from dyads with the sarcolemma.

ISSN:0706-652X    

DOI:10.1139/f68-120

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Walleye stocks in Nipigon Bay of Lake Superior were homogeneous with those in tributary inland waters but were discrete from Black Bay stocks. Returns from 2200 tagged walleyes in Lake Superior and tributary inland waters between 1955 and 1958 varied from 7.8 to 31.0% for 2 years after release. The commercial fishery in Lake Superior recovered 64.9% of the tags, the sports fishery in inland waters captured 27.6%. Fish tagged in the Nipigon River travelled a mean distance of 11.8 miles from the point of release and were recovered in 191 days (average). Total mortality rates for Nipigon Bay walleyes were 55.0% (1955–57). Mature walleyes on the spawning grounds in the Nipigon River in 1957 were estimated at 22,000, and fish in Nipigon Bay over 14 inches (total length) the same year at 41,000. All male walleyes were mature at 15 inches and females at 18 inches. Walleyes exploitation rates increased with the decline of the lake trout fishery. Wounding and scarring rates by sea lampreys increased during 1955–57 but never exceeded 1.0% on adult walleyes. Severe pollution on the west side of Nipigon Bay originated from a kraft mill. High concentrations of total solids and dense sedimentation of wood fibres created an environment unfavourable toHexagenia limbataandPontoporeia affinis. The recent elimination of the walleye fishery in Nipigon Bay is most likely attributable to industrial pollution rather than to overexploitation or sea lamprey predation.

ISSN:0706-652X    

DOI:10.1139/f68-121

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Marked success of rehabilitation of lake trout in Lake Superior has been due principally to the control of the sea lamprey and closure of the lake trout fishery in 1962 and large-scale plantings of yearling lake trout in 1959–66. After the sea lamprey became established in the late 1940s, spawning stocks of lake trout began to decrease and were almost nonexistent by 1960–61. After control of the sea lamprey and closure of the commercial fishery for lake trout in 1962, the abundance of spawning stocks began to rise and reached the highest levels on record in 1964–66. Successful spawning in 1964 and 1965 was demonstrated by catches of age-0 lake trout in 1965 and 1966, the first evidence of natural reproduction since 1959.Plantings of hatchery-reared lake trout in Wisconsin waters of Lake Superior began in 1952. The percentage of hatchery-reared fish in catches of juvenile lake trout increased almost steadily from 1953 to 1965 (when nearly all were of hatchery origin). The abundance of juvenile fish increased from 1959 to 1962 and remained nearly constant in 1962–66. The success of lake trout plantings was highest in 1959–61 but generally declined after 1961; the success of the plantings was inversely related to the abundance of older lake trout.Annual increments of growth of hatchery-reared lake trout varied from 1.1 to 5.0 inches after planting. The average lengths of fish of identical age-groups varied according to gear of capture, depth of water, and season. More than 65% of the season's growth of age-III lake trout took place after September.The findings indicated that the present rate of stocking lake trout may be higher than necessary to maintain optimum abundance.

ISSN:0706-652X    

DOI:10.1139/f68-122

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Recurrent species groups were formed by computer analysis from the data on occurrence of demersal fish at 480 trawl stations in the tropical eastern Atlantic; these recurrent groups were then marshalled into a small number of major species assemblages, or communities in the wide sense, on the basis of intergroup relationships. These assemblages proved to be remarkably similar in composition and ecology to the communities of demersal fish recognized earlier by a number of authors from their subjective analysis of trawling survey data in this region. The computer analysis provided finer detail on both the structure and distribution of the assemblages and their constituent groups. This confirmation of the reality of the subjectively recognized communities suggests (1) that the recognition of such assemblages by subjective methods has a place in the assessment of multispecies fish resources but (2) that where the method is practicable, the machine processing of recurrent species groups in the analysis of trawl survey data can be a valuable tool in resource evaluation.

ISSN:0706-652X    

DOI:10.1139/f68-123

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Keys, synonymy, descriptions, and distribution records are given for the eight American stonefly species of the genusTaeniopteryxPictet, including the new speciesburksi, lonicera, metequi, andugola.

ISSN:0706-652X    

DOI:10.1139/f68-124

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A series of tests were conducted to determine the effectiveness of pulsed low-frequency acoustic signals for attracting fishes. The acoustic signals were contrived to simulate the hydrodynamically generated disturbances normally associated with active predation. Underwater television was used to observe fish arrivals during both control and test periods. Demersal predatory fishes were successfully attracted although they habituated rapidly to the acoustic stimulus. Members of the families Serranidae, Lutjanidae, and Pomadasyidae were particularly well represented among the fishes attracted. Sharks were also attracted in considerable numbers. Herbivorous reef fishes, although common around the test site, were not attracted. Possible relationships between the test results and the hearing capabilities of fishes are discussed. It is concluded that acoustic attraction techniques have potential applications in certain existing commercial fisheries.

ISSN:0706-652X    

DOI:10.1139/f68-125

出版商:NRC Research Press    

年代:1968

数据来源: NRC