A total of 433 skulls of harbor porpoises, Phocoena phocoena, were examined to evaluate geographical variation within the western North Atlantic, using analysis of covariance and discriminant analysis based on 45 measurements of skull components. The relationship between condylobasal length and body length was sigmoid in both sexes. Condylobasal length is generally less in adult males than in adult females.
Despite some overlap, morphological differences between different regions and even adjacent local stocks could be recognized by ANCOVA and discriminant analysis. The percentage of correct classification by discriminant functions was 65.2% for the four regional samples: (1) North Canadian Atlantic (which includes Gulf of St. Lawrence and Newfoundland), (2) Bay of Fundy, (3) Gulf of Maine-New York, and (4) Maryland-South Carolina. It was 65.9% for the four local geographical areas (10s of km) within the Bay of Fundy; Quoddy-region porpoises revealed a closer relationship with the southwestern Nova Scotia population than with other adjacent stocks. The results at this level imply that gene flow is restricted to some degree even among closely adjacent geographical units. Management of this species should aim, therefore, for conservation of a variety of local stocks.