Comparative Survival and Growth of Two Strains of Atlantic Cod ( Gadus morhua ) through the Early Life Stages in a Marine Pond

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Blom, Geir, Svåsand, Terje, Jørstad, Knut E., Otterå, Håkon, Paulsen, Ole I., Holm, Jens C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1994
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Norway; atlantic cod; Gadus morhua
• Online Access: http://dx.doi.org/10.1139/f94-101; http://www.nrcresearchpress.com/doi/pdf/10.1139/f94-101

Survival and growth of two strains of Atlantic cod (Gadus morhua) were compared through the larval and juvenile stages in a marine pond in western Norway in 1990 and 1991. Strain A was homozygous for the genetic marker allele GPI-1*30 at the glucose phosphate isomerase (GPI) locus expressed in white muscle, and Strain B possessed other GPI-1* genotypes, in 1990 the frequency of Strain B increased significantly from the larval to the juvenile stage; however, in 1991 the frequency of Strain A increased slightly but not significantly from the larval to the juvenile phase. Larval mortality did not differ significantly between strains any year, but juvenile mortality was significantly lower in Strain B in 1990 and Strain A in 1991. Average growth rates in length estimated from regressions were not significantly different between strains during the larval and juvenile period any year, but initial length was significantly larger in Strain B in 1990 and Strain A in 1991. Our results indicated that food limitation during the early juvenile stage induced differential size-selective mortality among the strains due to small differences in body size and actual age between strains. Body size did not become important for survival until the food-limited regime had occurred.