© 2005 International Council for the Exploration of the Sea
Seasonal cycles in weight and condition in Atlantic cod (Gadus morhua L.) in relation to fisheries
Fisheries Conservation Chair, Marine Institute, Memorial University of Newfoundland PO Box 4920, St. John's, NL, A1C 5R3 Canada
*Correspondence to Luiz G. S. Mello: tel: +1 709 778 0652; fax: +1 709 778 0669. e-mail: luiz.mello{at}mi.mun.ca.
Seasonal cycle in weight and physiological condition of Atlantic cod (Gadus morhua) influenced productivity and economic impacts of the cod fishery in Placentia Bay, Newfoundland. Condition indices (Fulton's K condition factor and hepatosomatic index – HSI) were lowest during the spawning season (spring) and increased rapidly during the postspawning period, reaching maximum values by fall (K and HSI increased on average 24% and 82% between spring and fall, respectively). Somatic weight and condition indices varied seasonally. Condition indices were correlated with an industry index of product yield. Historically, cod fisheries have been prosecuted during all seasons, but simulations of 1997–1999 fisheries indicate that a fall fishery (period of peak physiological condition) resulted in a 8–17% decrease in the number of cod removed from the stock while maintaining the same weight-based quotas, and profiting from maximum yield and better product quality. Spring and summer fisheries resulted in lower yield (6%) and quality (5–26%) of fish products by weight. Seasonal biological cycles could be used as templates for management strategies that promote fisheries conservation and economic benefits by harvesting fish during periods when biological impacts are minimal and economic returns maximal.
Keywords: Atlantic cod, Fulton's K condition factor, harvesting strategy, hepatosomatic index, Placentia Bay, yield and quality indices, 3Ps
Received 15 March 2004; accepted 18 March 2005.