Genetic markers and whale stocks in the North Atlantic ocean: a review

Abstract

Abstract The discovery of protein electrophoresis and later of applying electrophoresis to DNA fragments is a powerful tool in comparing animals from different areas. We discuss our experience of using these techniques in comparing stocks of whales. The emphasis is laid on fin ( Balaenoptera physalus ), sei ( B. borealis ) and minke whales ( B. acutorostrata ). Of 31 enzyme systems encoded by 40 loci in fin whale liver samples from Iceland and Spain, 11 loci were found to be polymorphic. The average heterozygosity for these two stocks of fin whales was 0.074 and 0.083, respectively. There were between years differences observed in the fin whales suggesting substructures of the populations. The Nei's genetic distance between Icelandic and Spanish fins was 0.016. In a limited study of fin whale samples from Norway, Iceland and Canada there were statistical differences between enzyme loci tested. No between years differences were found in seis that came only from Iceland. The isozyme study of minke whales revealed genetic differentiation between Norway, Iceland and West Greenland. DNA finger-printing showed similar differentiation. Earlier morphometric comparisons and tagging experiments pointed in the same direction. Immunogenetical studies of the MHC region of fin and sei show lack of polymorphism in these species. The C4 is more similar to terrestrial animals regarding polymorphism. The C4 typing revealed hybridisation between blue and fin whales; three hybrids were found, one fertile female in her second pregnancy and two males. This demonstrates how closely related these two species are. The conclusion from our study is that fin whales from Norway, Iceland, Canada and Spain are separate stocks. The same applies to minke whales from Norway, Iceland and West Greenland; they represent different populations.