© 2003 by ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer
Winter and spring changes in condition factor and energy reserves of wild cod compared with changes observed during food-deprivation in the laboratory
Ministère des Pêches et des Océans, Institut Maurice-Lamontagne CP 1000, Mont-Joli, Quebec, Canada G5H 3Z4
*Correspondence to J.-D. Dutil; tel: +1 418 775 0582; fax: +1 418 775 0740. e-mail: dutiljd{at}dfo-mpo.gc.ca.
Atlantic cod were food-deprived for a period of 84 days at three temperatures (2, 6, 10°C), and changes in the liver, gonads and somatic weights, and muscle and liver water contents were monitored and compared with changes observed in wild cod over winter in the northern Gulf of St. Lawrence. Total lack of food during the period January–April would have caused condition to decline to a level at which very high mortality takes place. Actual changes in condition in wild cod were less than predicted from the laboratory experiments except during the period April–May at the onset of spawning. Thus, wild cod were able to meet part of the metabolic costs during winter through occasional feeding, as confirmed by stomach content data. We conclude that previous estimates of natural mortality associated with poor condition in spring were not biased by the selective mortality of poor-condition fish in winter.
Keywords: Atlantic cod, Gadus morhua, natural mortality, condition, energy, growth, maturation
Received 11 April 2002; accepted 18 February 2003.