摘要:

A rupture of the integument was shown to be essential for the transmission ofGaffkya homarito the lobsterHomarus americanus. The acidity of the lobster gastric fluid was bactericidal forG.homariand was an adequate barrier against transmission of gaffkemia by the oral route. Lytic activity associated with the larger protein molecules of lobster gastric fluid, but not with the bactericidal effect of the acid condition, was weakly active againstMicrococcus lysodeikticusbut was not active againstG.homari. The acidity of the lobster stomach is a function of the acidic protein molecules rather than a result of an excess of small, acidic molecules.

ISSN:0706-652X    

DOI:10.1139/f69-001

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Three phenotypes of lactate dehydrogenase (LDH) isozymes were found in sera of sockeye salmon (Oncorhynchus nerka), presumably representing B′B′, B′B, and BB genotypes. No association was obvious between LDH phenotype of sera and sex or total body length.Of 1006 sera from Asian, Bristol Bay, and Gulf of Alaska stocks, 826 were B′B′ and 180 were B′B or BB. Of 591 sera from Washington and British Columbia stocks, 589 were B′B′ and 2 were B′B; both of the B-allele phenotypes were found in fish captured at the Skeena River in northern British Columbia. These findings suggested that LDH isozymes should be useful in studies on ocean distribution of sockeye salmon and in characterizing certain Asian and Alaskan sockeye salmon populations.

ISSN:0706-652X    

DOI:10.1139/f69-002

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Juvenile smallmouth bass showed a marked response of utilizing opaque plastic coverts in a stream aquarium with two water velocities (12 and 28 cm/sec). The most complex of six opaque coverts at the higher water velocity was occupied a mean time of 7190 ± 6 out of 7200 sec. The presence of a visual reference point was the first feature to attract a fish to a covert for a marked period of time. The addition of an area of darkness increased the use of a covert. Maximum use was obtained with the above features plus an area of quiet water. Clear plastic coverts, which supplied only thigmotactic stimuli or thigmotactic stimuli and an area of quiet water, were rarely used.

ISSN:0706-652X    

DOI:10.1139/f69-003

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Lakeward migration of rainbow trout fry was studied in the upper Lardeau River, where the young emerge from a spawning area immediately below the outlet of Trout Lake utilized by large trout from Kootenay Lake, about 56 km downstream. Most fry move downstream towards Kootenay Lake shortly after emergence; however, some, particularly later in the emergence period, move upstream into Trout Lake. Field observations and experiments suggest that water temperature may be important in inducing different responses to water current in these fish, but may not play such a predominant role or operate at the same levels as proposed earlier for control of young trout migration in the Loon Lake system.

ISSN:0706-652X    

DOI:10.1139/f69-004

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Fresh mid- and hind-gut contents of young, hatchery-reared Atlantic salmon degradedp,p′-DDT top,p′-TDE in vitro. Most of the ability to degrade DDT, attributable to intestinal microflora, was eliminated by streptomycin and by heat-sterilization of the gut contents. Since TDE is less toxic than DDT, the activity of intestinal microorganisms may increase the chances of survival of fish that ingest DDT-contaminated prey.

ISSN:0706-652X    

DOI:10.1139/f69-005

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

During the period May 28 to August 1, 1967, benthic infauna was collected at 37 stations in Puget Sound and off the coast of Washington. When large but rare species were excluded from the samples, the variability in standing crop (ash-free dry weight) among replicate samples was less than among means from different stations. The mean standing crop for the offshore stations was 1.92 g/m2, which is comparable with the standing crop on the shelf in the Gulf of Alaska, but less than half the mean standing crop for the Puget Sound stations; the difference may be explained in part by differences, previously reported, in primary productivity of the water masses. For the offshore stations there was a weak trend of increasing standing crop with depth. The standing crop at the shallow-water offshore stations, in substrates characterized as fine sand, was dominated by crustaceans and small lamellibranchs, whereas at the deeper stations, in sediments with high percentages of silt and clay, polychaetes and echinoderms were the most important contributors.

ISSN:0706-652X    

DOI:10.1139/f69-006

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Competition among coho salmon fry in stream aquaria supplying natural drift was found to reflect the history of exposure of eggs and resulting fry to dissolved oxygen concentration prior to emergence. Size disparities induced by differential hypoxial stress were amplified with time, and fry that had been exposed to the most severe hypoxial conditions were most prone to emigrate. Most emigrants placed in an initially vacant, replicate system remained there, grew rapidly, and became as large as, or larger than, nonemigrants. Size of former emigrants reflected enhanced feeding opportunity due to less competition for food and space in the replicate system. Competition was referred more precisely to hypoxial history by using net production. A replicate population fed hatchery food provided a comparison. When exposed to the stream aquaria, this population substantiated the previous findings. Diel cycles of activity and aggression peaked at dawn and dusk, and were related to competition for food and space. The ecological significance of the results is discussed with particular regard to competition for food and space, and the effect of a size-related social order that put smaller individuals at a disadvantage.

ISSN:0706-652X    

DOI:10.1139/f69-007

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Measurements of the effect of rapid change in temperature on the spontaneous activity and oxygen consumption were made on Atlantic salmon underyearlings acclimated to 6 or 18 C. The new levels of imposed temperature ranged from 6 to 30 C for both acclimations. At similar test temperatures the calculated standard metabolic rate of the fish acclimated to 6 C was higher than that of the fish acclimated to 18 C, up to about 23 C, where the two curves relating oxygen consumption and temperature intersect. Spontaneous activity could be separated into two phases, a transient phase occurring during the actual period of temperature change, and a stabilized phase. The transient phase was characterized by a peak in activity which was found to be correlated with the rate, rather than the amount, of the temperature change. In general, the peak was higher for fish acclimated to 18 C. The relation between activity in the stabilized phase and test temperature was characterized by a plateau or maximum in the general region of the previously determined selected temperature. Except at the coldest test temperature (6 C), the fish acclimated to 6 C were more active in the stabilized phase than were the fish acclimated to 18 C at similar test temperatures. Complete acclimation for both metabolism and activity, between 6 and 18 C, requires about 2 weeks, regardless of the direction of the temperature change.

ISSN:0706-652X    

DOI:10.1139/f69-008

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Juvenile coho salmon (Oncorhynchus kisutch) fed a folic acid-deficient diet and sampled at 6, 9, 12, and 14 weeks developed macrocytic anemia. The anemia, first observed at 6 weeks, was characterized by a significant reduction in red blood cell count as well as macrocytosis and poikilocytosis of erythrocytes. The abnormally shaped erythrocytes observed in peripheral blood smears may be an important aid in the identification of folic acid deficiency in coho salmon. Gross manifestations of the deficiency were extremely pale gills; exophthalmia, often accompanied by ascites fluid; dark coloration; and reduction in growth. Fish recovered after 8 weeks on a diet adequate in folic acid and exhibited a normal blood picture.

ISSN:0706-652X    

DOI:10.1139/f69-009

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Coho salmon (Oncorhynchus kisutch) and rainbow trout (Salmo gairdneri) were highly resistant to endotoxins from bothEscherichia coliandAeromonas salmonicida(a fish pathogen) at 14 and 18 C.This resistance was investigated with liver tryptophan pyrrolase, liver glycogen depletion in vitro, and the arterial blood pressure as indicators. Liver glycogen depletion was accelerated by both endotoxins, but there was no significant cardiovascular response or effect on liver tryptophan pyrrolase activity. Since the cardiovascular effects of histamine were also limited, it was concluded that the metabolic effects of bacterial endotoxins in salmonids are qualitatively different from those of the higher vertebrates.

ISSN:0706-652X    

DOI:10.1139/f69-010

出版商:NRC Research Press    

年代:1969

数据来源: NRC