摘要:

Recoveries of drift cards indicate a generally easterly drift of surface water across Georgian Bay, corresponding to prevailing winds. No cards were recovered on the western side of the bay, suggesting persistent upwelling there.

ISSN:0706-652X    

DOI:10.1139/f56-001

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Chemical properties of the waters in Trevor Channel and Alberni Inlet during late summer have been applied for an estimate of basic productivity. Based on the assumptions that the deep water in the system is renewed once per year and that the observed conditions in September represent the state of the water just before renewal, the oxygen deficit and the phosphate surplus in the deep water have been used as a measure of the organisms decomposed during the year. Oxygen depletion gives 28 g/m2of plankton per year as carbon; phosphate liberation gives 31 g/m2. From fishery statistics it was estimated that the herring in Barkley Sound consume about one-quarter of the available plankton and all plankton feeders consume about one-half of the total. This would increase the above figures of productivity to 56 g/m2and 62 g/m2, respectively. These values are probably a minimum annual productivity inasmuch as basic assumptions may not be completely fulfilled. Regeneration of nutrients in the surface layer, and some renewal of deep water by mixing and circulation, probably occur throughout the year.

ISSN:0706-652X    

DOI:10.1139/f56-002

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

A study has been made of some of the factors affecting the spoilage rate of fish in the trawlers at sea. It was found that two conditions were major causes of accelerated spoilage: (1) Treatments that resulted in very heavy initial contamination such as storing the fish directly against the slimy wooden pen boards, and (2) Treatments that resulted in a rise in the temperature of the fish. This latter may be a larger increase in temperature for a short period, such as exposure of the fish on the deck during warm summer weather, or a smaller increase over a longer period, such as results from inadequate or inefficient icing.Other types of carelessness and unsanitary conditions did not have any significant effect on the fish until at least 6 or 7 days, as long as they were well iced during the subsequent storage period in the hold.

ISSN:0706-652X    

DOI:10.1139/f56-003

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

A list is given of 89 stations where biological or oceanographic observations or collections were made by theCalanusin Hudson Bay, western Hudson Strait and Ungava Bay, during the 1953 and 1954 seasons.

ISSN:0706-652X    

DOI:10.1139/f56-004

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Quick frozen freshly shucked oysters stored at −10°F. (−23 °C.) did not deteriorate significantly during a storage period of 9 months, as assessed by taste panels on the simmered oysters. Slow freezing and storage at higher temperatures resulted in a much greater loss in quality, and objectionable darkening occurred. Preparation as a stew largely masked this deterioration.

ISSN:0706-652X    

DOI:10.1139/f56-005

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The net plankton of Great Slave Lake was studied extensively in the years 1944 to 1947 and sampling continued at a central station through 1954. Some 490 samples were taken using large nets and traps with No. 20 silk. Taxonomic, gravimetric and numerical analyses are reported and comparisons made between the larger, open lake and the deep, cold, east arm.Among 160 species of algae, two diatoms,Melosira islandicaandAsterionella formosawere dominant. Green and blue-green algae were scanty butDinobryonwas numerous, especially in the cold, east arm. Among 26 rotifersKeratella cochlearisandKellicottia longispinawere dominant and four other species common. Cladocera were scarce but the copepods made up about 85% of the plankton volume.Diaptomusspp.,Cyclopsspp.,Limnocalanus macrurus,Epischura lacustrisandSenecella calanoideswere the main species.The average dry weight of the standing crop of net plankton in the open water was 21.8 kg./ha. The crop was heavier in years of warm water than in those of colder water. Occasional high turbidity was associated with decreased plankton. In Christie and McLeod Bays of the east arm, where the waters are deeper, colder and lower in mineral content, the average dry weight of plankton was 14.3 and 9.0 kg./ha. These amounts are typical of the plankton in large, very oligotrophic lakes.An early season maximum of diatoms and copepods was followed by a rapid decline in late July. The smaller, late-summer maximum included large numbers of rotifers. More than half of the plankton was in the upper 25 metres with decreasing amounts down to 100 metres. A thin plankton, mainly of copepods, extends down to 600 metres.The dominant species of plankters in the open water of Great Slave Lake appear to be almost identical with those of Lake Winnipeg, Lake Nipigon and the Great Lakes. All have a diatom-copepod type of plankton with a constant group of rotifers andDinobryonin moderate numbers. Green and blue-green algae are scanty except in the shallower and warmer lakes, Winnipeg and Erie.

ISSN:0706-652X    

DOI:10.1139/f56-006

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Taste panel assessments of taste, texture, and grade, and estimations of soluble actomyosin and of fat spoilage on plaice fillets after frozen storage at + 10°F. (−12 °C.) are reported. The plaice became unpalatable at 6 to 7 months as compared with 2 to 3 months for cod and about 8 months for Atlantic halibut at +10°F. Ascorbic acid was not effective in preventing lipid deterioration. A relationship between protein denaturation and the lipid content of the fish and its deterioration is suggested.

ISSN:0706-652X    

DOI:10.1139/f56-007

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Pigeon Lake, Alberta, is a shallow eutrophic lake with a sandy basin, gentle contours and an area of 40 square miles. It contains whitefish, pike, yellow walleye, perch, burbot, white suckers and spottail shiners. The whitefish have been commercially exploited for many years and catch statistics are available from 1918.In 1941 a greatly increased catch of whitefish was permitted. Large annual yields continued until 1946; in 1947, in spite of considerable effort, a very small catch was made. Since this collapse fishing was prohibited in two years and light in two years. The lake now contains a normal whitefish population.Samples of the commercial catch during this period showed that the average age of the fish fell from 5.1 to 2.3 years, then, after collapse, increased to 5.7 years. Growth rates increased greatly, then decreased to the original level. Age at maturity decreased from five to two years.Calculations of the number of fish each year-class contributed to the fishery reveal that the collapse of the fishery was not due to overfishing; the weak year-classes which caused the collapse had parent year-classes of normal abundance. It is suggested that egg destruction by strong winds may have caused the weak year-classes.

ISSN:0706-652X    

DOI:10.1139/f56-008

出版商:NRC Research Press    

年代:1956

数据来源: NRC