Trypsin isozymes in Atlantic salmon, Salmo salar L.: studies of heredity, egg quality and effect on growth of three different populations

Abstract. Isoelectric focusing of Atlantic salmon, Salmo salar L., trypsin resolved three major isozymes designated TRP-1, TRP-2 and TRP-3, with three variants, TRP-l(9l), TRP-l(75) and TRP-2(92). The TRP-1 and TRP-2 may represent duplicated loci which exhibit either tetrasomic or disomic inheritance from pairing of homeologous chromosomes. A significant difference in growth during 3 months after first-feeding was observed in the families exhibiting a high frequency of the isozyme TRP-2(92) (f≥0·5). Studies of three salmon populations suggested a correlation between the presence of this isozyme and better growth rate. No difference in egg quality was observed between the families possessing and lacking the trypsin isozyme TRP-2(92).