摘要:

Morphometric and hydrographic conditions indicated Nabisipi River, Quebec, has a fjord-type estuary with warm surface water of low salinity flowing out over cold saline water from the Gulf of St. Lawrence at all phases of the tidal cycle. The age, weight, and condition factors of 231 juvenile salmon from the estuary and 200 from the lower reaches of the river are given. Ages ranged from 1+ to 4+, condition factors (100 × weight in grams divided by the length in centimeters cubed) were slightly below 1.0 in the river and slightly higher in the estuary. Amphipods and capelin eggs were important constituents in the diet in the estuary, Corixidae in the river. Tagging indicated a growth rate of about 0.8 mm/day in the estuary. Both tagging and the handling of marked fish retarded growth. Tagging retarded growth for approximately 20 days. Tagging returns indicated a population of between 700 and 2500 fish near the mouth of the estuary in June and July 1961. These were thought to be remnants of the spring smolt run. In addition there was a small resident population of salmon parr living in the estuary. Numbers of fish in the estuary changed considerably from year to year.

ISSN:0706-652X    

DOI:10.1139/f66-088

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Theoretical aspects of the influence of the temperature of maximum density of water on the circulation of deep cold lakes are applied to the temperature structure of Great Bear Lake. In general good agreement between observation and theory is found. In most years summer circulation does not extend below a depth of 225 m as stability at lower levels is sufficient to prevent it. In cold years with slow heating, circulation extends to the bottom (450 m). In winter the lower half of the lake is isothermal at the temperature of maximum stability (3.53 C) of the bottom water. This is explained on the basis of the slope of the line of maximum density being double that of the slope of the line of maximum stability. When the water at a depth of 225 m is cooled to 3.53 C the point of maximum temperature in the profile at this depth is removed so that isothermy develops in the lower half of the lake.

ISSN:0706-652X    

DOI:10.1139/f66-089

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Changes in body weight, liver weight, liver glycogen, blood plasmapH, hematocrit, plasma protein, and glucose levels in the Atlantic cod (Gadus morhuaL.) during feeding, fasting, and liver regeneration are recorded. Resting liver glycogen content (37 ± 7 mg/100 g liver) is much lower than in many terrestrial and freshwater vertebrates. There is a transient increase in liver glycogen (702 ± 188 mg/100 g liver) with resumed feeding after prolonged fasting. Average resting levels of plasma protein (4.66 ± 0.36% w/v), glucose (100 ± 4 mg/100 ml plasma) and hematocrit (23.2 ± 1.2% v/v) decreased during the initial stages of food depletion. A reversal of this trend resulting in apparent increased levels is observed in acute malnutrition. This is attributed to dehydration of plasma with consequent drop in the total blood volume. The steady increase in plasmapH (7.24–7.54) with the duration of fasting may be due to extensive deamination of tissue protein amino acids for gluconeogenesis.

ISSN:0706-652X    

DOI:10.1139/f66-090

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Fingerling and yearling trout (Salmo gairdneriRichardson) responded differently when exposed to a series of artificial daylight illuminations. Fingerling trout showed no apparent response to the overhead cover, being randomly distributed at all light intensities. Yearling trout, except in total darkness, exhibit a positive response to the overhead cover, but their pattern of behaviour differed with the light intensity and the positioning of the cover.

ISSN:0706-652X    

DOI:10.1139/f66-091

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Twelve commercial samples of oil from Atlantic herring (Clupea harengusL.) were examined for fatty acid composition by gas–liquid chromatography. Individual fatty acid components varied widely between these oils, but an assessment of the respective totals of saturated, monounsaturated, and polyunsaturated acids from these oils and from oils of other species has led to an empirical formula giving the total per cent polyunsaturated fatty acids in marine oils as: total polyunsaturated fatty acids = 10.7 + 0.337 (iodine value oil — 100)In the Atlantic herring oils studied the average proportions of the saturated, monounsaturated, and polyunsaturated fatty acids were 20, 60, and 20%, respectively. In comparison with herring oil analyses reported from other areas the total saturated acids in the Atlantic herring oils are slightly lower, but there is general agreement that hexadecanoic acid averages about 60% of the total saturated fatty acids. Relationships which are fairly consistent among other acids and apparently not related to iodine value include the ratio of hexadecanoic acid to hexadecenoic acid plus octadecenoic acid, the ratio of C20and C22successor acids to C18linoleic-type precursor acids, and the ratio of linolenic-type acids compared to immediate precursors of the same chain length. As iodine value increases the saturated acids increase slightly, and in the linolenic type acids the ratio of C20to C18fatty acids increases more noticeably than the ratio of C22to C18. The ratio of C22to C20linolenic-type acids accordingly decreases with increasing iodine value. The ratio of total linolenic-type acids to total linoleic-type acids apparently increases with increasing iodine value. Comparisons are made with oil analyses of clupeids taken in other oceanic areas.

ISSN:0706-652X    

DOI:10.1139/f66-092

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Responses of young Atlantic salmon (Salmo salarL.) and of brook trout (Salvelinus fontinalis(Mitchill)) to different levels of illumination and to overhanging and submerged cover were compared in the laboratory. At surface illuminations between 0.4 and 160 ft-c trout were either slightly photopositive or showed no preference for light or dark areas, while salmon were photopositive. At illuminations above 300 ft-c both species were photonegative when the light area had a smooth, unbroken substrate. Under these conditions starvation induced salmon into the light, but trout remained photonegative, although slightly less so than well-fed trout. With submerged cover (plants, broken flowerpots, etc.) in the light area, salmon were strongly photopositive, while trout were photonegative. Salmon were less photopositive, but still preferred the light area, with submerged cover in both dark and light areas, in most experiments trout maintained position at the edge of the shadow caused by overhead cover, looking out into the light area from the dark.The significance of these results to habitat segregation by the two species where they are sympatric in nature is discussed.

ISSN:0706-652X    

DOI:10.1139/f66-093

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The lipid composition of fresh and frozen cod (Gadus morhua) muscle was studied using silicic acid chromatography. Dark cod muscle contained about three times as much total lipid as white muscle but the composition was quite similar. The most significant difference was that the dark tissue lipid contained more esterified cholesterol and less phosphatidyl choline. Frozen storage for up to 9 months at −12 C showed that the free fatty acid content increased from 5 to 326 mg/100 g tissue due to the hydrolysis of phosphatidyl ethanolamine and phosphatidyl choline. Other phospholipids were not hydrolyzed. Phosphatidyl ethanolamine hydrolysis ceased after storage for 4 months, whereas hydrolysis of phosphatidyl choline continued thereafter at a slower rate. After 9 months, the phospholipid content of the total lipid had dropped from 84 to 32% and only 13% of the original phosphatidyl ethanolamine and phosphatidyl choline remained unhydrolyzed.

ISSN:0706-652X    

DOI:10.1139/f66-094

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Fifteen- and 25-hr-old zebrafish (Brachydanio rerioHamilton-Buchanan) embryos with the outer egg membrane ruptured survived longer in a solution of zinc sulphate (20 ppm Zn) than embryos of the same ages with the membrane intact. Forty-two-hour embryos with the membrane completely removed survived in four concentrations of zinc sulphate (2.5, 5, 10, and 20 ppm Zn) at least as long as 42-hr embryos with the membrane entire. The high resistance of zebrafish embryos to zinc was therefore not owing to protection by the membrane. On the contrary the presence of the membrane lowered resistance.This result was probably owing to the formation of opaque material enclosed by the outer egg membrane of zinc-poisoned, unruptured eggs. The action of this material in reducing survival is unknown.

ISSN:0706-652X    

DOI:10.1139/f66-095

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Migration, distribution, and movement of five groups of fin-marked coho salmon of the 1950 brood planted into Puget Sound, Washington, in 1952, were followed during 1952 and 1953 by a study of 847 recoveries of marked salmon taken in sport and commercial fisheries in the Pacific Ocean, Puget Sound, and closely adjoining regions.Differences in migration, distribution, and movements of the five groups of salmon were correlated with the time, place, and method of planting.The most pronounced difference in behavior was shown by salmon receiving an extra 2 months of rearing in the hatchery as compared with other groups. This group was marked by removal of the dorsal and right ventral fins. A lag in average time of migration to points in the ocean and a tendency to migrate lesser distances while in the ocean characterized the behavior of these fish. This lag in time of migration as indicated by patterns of recovery of marked salmon from sport and commercial fisheries was confirmed by an actual lag in time of return to the point of release.In migrating from off the coast of Washington to Puget Sound, the salmon moved at an estimated rate of 5–7 nautical miles per day.

ISSN:0706-652X    

DOI:10.1139/f66-096

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Taste panel assessment is reported for Atlantic cod (Gadus morhua) frozen once and twice, and stored at −23 C. The fish were bled, gutted, and iced immediately after capture, and frozen as fillets or dressed fish before, during, and after rigor mortis. Dressed fish were thawed later in recirculated tap water, then processed, refrozen, and stored as fillets. The procedure was conducted three times (June 27, July 19, July 30) during the inshore trap fishery and twice (March and October) during the offshore Grand Bank fishery.For trap-caught landings, the quality of the stored fillets frozen once depended upon the season of catch; for Grand Bank cod, upon the time and place of catching. Trap fish, feeding lightly, caught in cold water in June, were of best quality, grades equalling 70 and over after 20 weeks storage. Those caught on July 30 while feeding heavily in warm water were second; the July 19 fish, obtained under nearly similar conditions, were not significantly poorer than those taken on July 30 and were still acceptable. March landings of Grand Bank fish, once frozen, scored over 70 after 20 weeks storage; October landings only 40 (borderline quality) after 30 weeks. Physiochemical and chemical assessment confirmed the poor quality of the latter.Thawing, refreezing, and storage of June trap fish longer than a few weeks resulted in poor but still acceptable samples. The stored product was soon similar in quality to samples prepared from July landings. In contrast, twice-frozen samples prepared from the March landings from the Grand Bank continued to score high, 70 after 28 weeks storage. Refrozen October samples from the Grand Bank yielded much lower scores, similar to those given the once-frozen samples of the same catch. Thus, in general, an acceptable or better twice-frozen product was obtained by starting with material well handled and quickly chilled, from either the inshore or offshore fishery.

ISSN:0706-652X    

DOI:10.1139/f66-097

出版商:NRC Research Press    

年代:1966

数据来源: NRC