© 2004 by ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer
Variant colourations of Atlantic cod (Gadus morhua) in Newfoundland and Labrador nearshore waters
a Environmental Science Programme, Memorial University of Newfoundland St John's, Newfoundland, Canada, A1B 3X5
b Ocean Sciences Centre, Memorial University of Newfoundland St John's Newfoundland, Canada, A1C 5S7
*Correspondence to J. S. Wroblewski: tel.: +1 709 737 2410; fax: +1 709 737 3018. e-mail: jwroblew{at}mun.ca.
Adult cod (Gadus morhua) inhabiting continental shelf waters of the Northwest Atlantic typically display a countershaded colouration: a dark back gradating to a light underbelly. Some cod in Newfoundland and Labrador inshore waters have predominantly brown or red pigmentation. Cod inhabiting Gilbert Bay in Labrador often have golden-brown colouration, likely the result of an invertebrate diet rich in carotenoids, and are known in the vernacular as the "golden cod of Labrador". To determine the stability of these variant colourations, we captured cod from Gilbert Bay, held them in a net pen and fed them a diet of fish. Over the 12-week experimental period, the variant coloured cod lost much of their brown or red pigmentation, and became countershaded. Because of its impermanence when cod switch from invertebrate to fish prey, variant colouration of cod can provide only provisional information about stock origin.
Keywords: Atlantic cod, body colouration, carotenoids, diet
Received 20 October 2003; accepted 25 April 2004.