Seasonal trends in spawning condition and catch rates of Atlantic cod (Gadus morhua) in northern Placentia Bay, Newfoundland, over 1995-1999

Bolon, Aline D. P. (1999) Seasonal trends in spawning condition and catch rates of Atlantic cod (Gadus morhua) in northern Placentia Bay, Newfoundland, over 1995-1999. Masters thesis, Memorial University of Newfoundland.

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Abstract

To describe the temporal spawning of cod and its relation to water temperature, sexual maturity, length, and age, the condition and gonado-somatic index of Atlantic cod sampled at four sites in northern Placentia Bay were monitored from March 1998 to April 1999. Similar information collected by the Department of Fisheries and Oceans over 1995-1997 was added to this data set. A histological procedure was used to verify spawning condition and improve the visual classification of spawning females. The visual classification was found to underestimate the percentage of spawning females by up to 29.7 %. No significant differences of biological variables and temperatures were found among the four fishing locations. Spawning fish were present from March to August, and several peak spawning periods per year were observed. A correlation between spawning patterns and temperature existed, but with a difference between sexes. Catch per unit effort, which gave a representative image of movement and abundance of fish, was more important in fixed than free locations, and was low during the spawning season.

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