The biology of the cod (Gadus morhua (L.)) of the northeast coast of Newfoundland

Wells, Richard (1968) The biology of the cod (Gadus morhua (L.)) of the northeast coast of Newfoundland. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (4MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The biology of the cod of the northeast coast of Newfoundland is analyzed from observations made in various years in the period 1940-65 but mostly in the 1960's. Age and length distributions indicate that numbers of older and larger fish have declined over this period. Year-class dominance, not present at the beginning of the period, is now evident. The growth rate and total mortality rates have increased. The changes listed above have been attributed primarily to an increase in fishing effort. Age at sexual maturity is lower for males than for females but the range of ages over which sexual maturity takes place is the same. There are indications that the stock is made up of more or less distinct inshore and offshore substocks.

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