Research Document - 1999/045

Temporal Trends in Condition, Gonado Somatic Index and Maturity Stages of Atlantic Cod (Gadus morhua) from Northern Placentia Bay (Subdivision 3Ps), Newfoundland, during 1998.

By A. D. Bolon and D. C. Schneider

Abstract

The maturity stage, condition and gonado-somatic index of cod sampled at four sites in northern Placentia Bay were monitored from March to December 1998. A histological procedure was used to determine whether the visual classification of female cod in spawning stage could be improved. The duration and timing of spawning at each site was determined. Among females, spawning fish were present from March to August with a peak spawning period from May to August. The males had two peak spawning times. One during April and one from the end of June to early August. Females had a peak spawning time spreading over two month while males' largest peak spawning period spread only over one month. During the spawning period, the condition of males and females were similar among the sites, ranging between 0.7 and 0.8. Their gonado somatic index reached a peak by the end of June and then decreased until the end of August. This supported the maturity stage data that spawning fish could be found until late August. When comparing the visual to the histological procedure used to classify the gonads, the visual procedure underestimated the percentage of spawning females by up to 29%.

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