MITOCHONDRIAL-DNA ANALYSIS OF HARBOR PORPOISES (PHOCOENA-PHOCOENA) INTHE BALTIC SEA, THE KATTEGAT-SKAGERRAK SEAS AND OFF THE WEST-COAST OFNORWAY

Incidental mortality of harbour porpoises, Phocoena phocoena, from cap tures in fishing gear has been documented consistently as severe in so me European waters. Since fishing effort varies greatly among regions, management units must be defined for more effective conservation of t his species. In this study, analysis of mitochondrial DNA (mtDNA) rest riction fragments was performed to investigate the population structur e of harbour porpoises in the Baltic Sea, the joint Kattegat-Skagerrak Seas and off the west coast of Norway. Mitochondrial DNA of 65 harbou r porpoises collected from three regions was analysed with nine restri ction enzymes. Analysis of the heterogeneity in the frequency distribu tion of haplotypes among provisional subpopulations revealed significa nt differences, which supports the recognition of three different subp opulations and thus three separate management units. Furthermore, indi ces of haplotypic diversity (range: 0.211 to 0.628) and nucleotide div ersity (range: 0.070 to 0.168) of these provisional subpopulations wer e much lower than for western North Atlantic subpopulations, which is consistent with the view that harbour porpoises in European waters, pa rticularly in the Baltic Sea, are depleted.