Age, length and reproductive parameters of harbour porpoises Photocoena phocoena (L.) from West Greenland

During 1988, 1989 and 1995, 187 harbour porpoises (Phocoena phocoena) were sampled from the catches off West Greenland during the months of July. Augu st and September. The samples were taken between 62 degreesN and 69 degrees 30 'N in Maniitsoq and three more northerly locations (134), Paamiut (23), and Nuuk (30). Comparison of age and length distributions between years an d areas, indicated that there were no significant differences between years . However. the Maniitsoq and northerly samples had a modal age in both sexe s of about 2 yr and a maximum age of 17 yr, while the more southerly Nuuk a nd Paamiut samples were biased to younger age classes, with the modal age i n both sexes being the first year of life (age class 0 yr) and a maximum ag e of 12 yr. Females ovulated from age 3.6 yr at a length af about 142 cm: combined test es weights > 200 g indicated maturation in males from age 2.5 yr upwards at a length > 125; cm. Several small embryos were found. consistent with a ma ting season in late summer. Testis hypertrophy in August was also consisten t with a late summer breeding. Application of growth models indicated an av erage asymptotic length of 154 cm in females and 143 cm in males. Comparisons of the West Greenland data with similar data for porpoises from the Canadian Atlantic. eastern North Atlantic and the North Sea. where gen etic studies have shown population differences. indicated differences in bi ological parameters.