Showing papers on "Atlantic cod published in 1981"

Vertebral Numbers in Atlantic cod,Gadus morhua, of the Newfoundland and Adjacent Areas, 1947-71, and Their use for Delineating Cod Stocks

Abstract: A total of 416 cod vertebral samples collected from the Newfoundland and adjacent areas during 1947-71, are analyzed in relation to their use for delineating the cod stocks of the region. Differences greater than two vertebrae were found between the highest and lowest vertebral means for different stocks. The overall vertebral mean for females exceeded that for males by 0.10. The main portion of the Labrador-East Newfoundland stock (Div. 2G to 3K) was well separated from the southern Grand Bank stock (Div. 3N and 30) by the presence in the northern area of high vertebral means and of higher percentages of high vertebral numbers and the lack of low vertebral numbers. This contrasted with vertebral means about one to two vertebrae lower in the southern Grand Bank stock, with higher percentages of low vertebral numbers and a lack of high vertebral numbers. Cod from the offshore area in Div. 2G to 3K had somewhat higher vertebral numbers than those of the inshore area. The high vertebral-count cod of the Labrador-East Newfoundland stock also extended to the northern slopes of Grand Bank and around the Avalon Peninsula (Div. 3L), but in this area they usually intermingled with cod of the Avalon stock complex and with some migrants from southern Grand Bank as indicated by vertebral means intermediate between the northern and southern extremes. In the Labrador-East Newfoundland stock, vertebral means were slightly lower in 1961-71 than in 1947-60. Vertebral means for cod off West Greenland were considerably lower than those for Labrador cod and similar to those for the southern Grand Bank stock. On St. Pierre Bank (Subdiv. 3Ps), some samples had as low vertebral means as those on Grand Bank whereas other samples had intermediate vertebral means similarto those in the adjacent coastal area. The northern Gulf and southern Gulf stocks, north and south of the Laurentian Channel in the Gulf of St. Lawrence (Div. 4RST), had low vertebral means, except for evidence of the intrusion of some cod with high vertebral numbers in and near the Strait of Belle Isle. Vertebral means declined from north to south on the Scotian Shelf (Div. 4VWX) and to Georges Bank (Div. 5Z). Spawning times of cod in various parts of the Northwest Atlantic are reviewed, and vertebral numbers for the different areas and stocks are related to the surface temperatures and current drifts following spawning. The lowest surface temperatures during egg and early larval development were associated with the longest period of egg and larval drift, the highest vertebral means, and the largest, most-widely distributed stock.

Antifreeze glycoproteins in the plasma of Newfoundland Atlantic cod (Gadus morhua)

Abstract: The plasma of the Atlantic cod, Gadus morhua, contained antifreeze glycoproteins which were present only during the winter months. The antifreeze proteins were isolated, using gel filtration and io...

Ultrastructure and prevalence of viral erythrocytic necrosis (VEN) virus in Atlantic cod, Gadus morhua L., from the northern Atlantic Ocean.

Abstract: . Blood samples were taken from Atlantic cod, Gadus morhua L., and several other marine teleost species in the northwest Atlantic Ocean to determine the prevalence of viral erythrocytic necrosis (VEN). The infection was found in G, morhua at a level of approximately 1.5° in the samples collected from both Newfoundland and Greenland. The latter finding extends the geographic range of VEN infection in this species. Ultrastructural details of the virus in erythrocytes of G. morhua from Greenland differed in several morphologic features from those previously reported.

Differentiation of Atlantic cod Gadus morhua morhua and pacific cod Gadus morhua macrocephalus by electrophoresis and by isoelectric focusing of water-soluble proteins of muscle tissue

Abstract: 1. 1. The water-soluble proteins of the skeletal muscle of Atlantic cod Gadus morhua morhua and Pacific cod Gadus morhua macrocephalus have been examined by electrophoresis and by isoelectric focusing in polyacrylamide gel. 2. 2. The species were readily differentiated either by electrophoresis or by isoelectric focusing. 3. 3. It is suggested that differences between the patterns of these two types of cod are of the order of those found between separate species rather than variants of a single species.

Variation in Vertebral Averages for Year-Classes of Atlantic Cod,Gadus morhua, on Flemish Cap

Abstract: Analysis of the average numbers of vertebrae in 21 year-classes of Atlantic cod, Gadus morhua L., produced on Flemish Cap during 1940-66, indicated min imal variation in vertebral averages among year-classes. Although variances of the vertebral frequencies for these year-classes were found to be heterogeneous and their means significantly different, the variances of 17 vertebral frequencies were homogeneous and their means, ranging from 54.37 to 54.78, did not differ significantly. It was concluded that the factors responsible for determining the vertebral numbers in cod on Flemish Cap are not subject to great variation.

Production Responses for Multi-species Fisheries

Abstract: Production equations are estimated for five major species of fish harvested in the Northwest Atlantic including Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), flounder (Pleuronect...