摘要:

Concentrations of zooplankton observed at Station "P" (50°N.L., 145°W.L.,) are less than those in the Northwest Pacific, the Bering Sea, British Columbia coastal waters and the Labrador Sea; about equal to those at Station "M" in the Norwegian Sea; and greater than those in the central Equatorial Pacific and the Sargasso Sea. Zooplankton abundance at Station "P" appears representative of that in a wide area of the central Gulf of Alaska. A vertical distribution of zooplankton characterized by maxima of concentration from 0–100 metres and from 200–500 m was observed both day and night and in all seasons. Daily means of concentration of surface zooplankton ranged from about 20 g per 1000 m3in winter to about 150 in summer. A small autumn maximum was observed. A similar seasonal cycle of abundance occurred down to depths of about 200 m. Below 200 m the amplitude of the seasonal cycle tended to decrease with depth. Vertical hauls captured mainly copepods all year round. Horizontal surface tows revealed a marked seasonal cycle in taxonomic composition. A pronounced diurnal variation in the concentration of surface zooplankton was observed and showed the major features of typical diurnal vertical migration. Night catches of vertical hauls exceeded day catches.

ISSN:0706-652X    

DOI:10.1139/f61-001

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A study of the herring of the south and west coasts of Newfoundland in 1957 and 1958 revealed no great fluctuations in relative year-class strength and indicated a fairly high survival rate from the age of recruitment to the fishery.The rate of growth was higher than that found by Tibbo (1956) in 1942–44, and no significant difference in growth rate was demonstrated between the south coast and the region of Bay of, Islands and Port au Port Bay.The study indicated an unusual spread in spawning time with probably peaks in spring, autumn and winter, while prior to about 1950 the Newfoundland herring were apparently all spring spawners. It is suggested that this has caused changes in the traditional pattern of distribution, which have been unfavourable for the herring fishery, and it may also have resulted in an actual decrease in population size.

ISSN:0706-652X    

DOI:10.1139/f61-002

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Glycerin-preserved otoliths of burbot,Lota lota, often become opaque and difficult to age; they become readable if heated in glycerin for 10 minutes at 190 °C, or for longer times at lower temperatures.

ISSN:0706-652X    

DOI:10.1139/f61-003

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Phytoplankton samples, collected in 1953 and 1954 by theCalanusexpeditions, were examined by the quantitative sedimentation method in an attempt to determine the ecological aspects of phytoplankton production in Hudson Bay and Strait. During the period July to September of both years, water temperature data, and salinity, oxygen and quantitative phytoplankton samples were collected at the surface and from depths of 10, 25, 50 and 100 metres. Numerically, the most abundant, heterogeneous phytoplankton populations were found in the mouth of Hudson Bay. The lower production of phytoplankton in the surface layer can be explained by the greater amplitude of temperature and salinity, dependent upon ice conditions and surface wind drift. The most productive layer was at a depth of 10 m. Large phytoplankton populations in waters supersaturated with oxygen were still found at 25 m, indicating light conditions favourable for photosynthesis. The relatively high plankton production in the area joining Hudson Bay and Hudson Strait is probably due to the hydrographic structure and the supply of nutrients resulting from the mixing of water masses which originate in other geographical areas. The preponderance of diatoms over flagellated groups, which is more marked in Hudson Strait than in Hudson Bay, is typical for the arctic. The composition of phytoplankton in these areas shows a great similarity in the main to that found on both sides of the Atlantic. Apart from locally produced plankton populations, there is a population exchange which follows water movements. To supplement the meagreness of existing taxonomic descriptions, attention is here focussed on the identification of plankters and their individual importance in the general ecology of the phytoplankton.

ISSN:0706-652X    

DOI:10.1139/f61-004

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Rats were used to test the digestibility and protein quality of dried preparations of muscle and viscera from cod and haddock, and of liver from cod.The digestibility of the preparations from muscle and viscera was good, and better than that of the preparation from liver.The metabolic utilization of nitrogen and the support of growth were good in the case of the muscle preparation, and poor in the case of the visceral and liver preparations.

ISSN:0706-652X    

DOI:10.1139/f61-005

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Nearly all the herring landed on the British Columbia coast during the past 10 years has been converted by the wet reduction process to animal feed, the bulk of which was in the dry form. While the final products of the wet reduction process have proven to be of a high nutritive value, in the dry form they have the disadvantage in the amount of handling required during transit. A liquid product would not only reduce handling costs but also it would act as a binder in otherwise dry feed rations.Three methods have been tested to liquefy the whole herring: ensilage, high pressure steam liquefaction and proteolytic enzyme solubilization. In the ensilage process the liquefaction of the whole fish in an acid medium was achieved in 72 hours at 37 °C. The liquefaction of the fish was shown to be due to proteolysis by the natural occurring enzymes present both in the viscera and in the flesh of the fish and was not caused by the action of bacteria. While up to 70% of the whole fish was solubilized by autoclaving the fish in an acid medium, the resulting free oil was high in free fatty acid content and the liquid concentrate dark in colour. Of the commercial proteolytic enzymes tested, pepsin achieved the highest maximum solubilization, followed by bromelin and Rhozyme B-6. An oil–protein emulsion stable at 100 °C and to salting, however, was formed in the digest of each enzyme tested.Liquid fish products were prepared under pilot-plant conditions for future nutritional assay.

ISSN:0706-652X    

DOI:10.1139/f61-006

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Experimentally prepared "liquid fish" made from British Columbia herring was compared with presscake herring meal, whole herring meal and condensed herring solubles as a source of supplementary protein for chicks. Two samples of liquid fish made by an enzymatic and by a high-pressure acid treatment respectively were tested. The two preparations were similar in protein value and gave a growth response intermediate between that obtained with herring meal and with condensed herring solubles.

ISSN:0706-652X    

DOI:10.1139/f61-007

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The following quadratic equation relating fork length to scale radius is derived for Atlantic salmon taken in the Miramichi commercial fisheries:where L = fork length in cm; and S = anterior scale radius in mm. The value 2.40 represents the fork length in cm of the fish when the scales first appear. Smolt transformation occurs after the young have reached an approximately similar size (about 12 cm) regardless of age. Five-year-old fish with 3 river years and 2 sea years predominate in the catch. Repeat spawners constitute only about 1/20 of the catch of salmon larger than grilse.

ISSN:0706-652X    

DOI:10.1139/f61-008

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Three groups of trout, two introduced populations ofSalmo gairdneriand a residentSalmo clarki, were studied in stream sections. Liver glycogen deposits, which were reduced to low levels during transportation to the stream, were restored in 2 to 3 weeks in all groups, with recovery rates being approximately inverse to the population density. Within the hatchery groups, larger fish laid down greater glycogen stores. Wild trout maintained their high glycogen reserves throughout the experiment.

ISSN:0706-652X    

DOI:10.1139/f61-009

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Slicing cod fillets longitudinally into slicesinch (13 mm) thick can increase the efficiency of candling cod fillets for codworms to over 95%. The increase is greater in the larger fillets than in the smaller fillets if sliced. If fillets are not sliced the candling efficiency decreases with increasing size of fillets.

ISSN:0706-652X    

DOI:10.1139/f61-010

出版商:NRC Research Press    

年代:1961

数据来源: NRC