External morphology and weight - length relationships (WLRs) of harbour porpoise, phocoena phocoena (Cetacea: Phocoenidae) in the Black Sea

Abstract

The present study summarized information on the morphometric characteristics and weight-length relationships (WLRs) of pregnant females, non-pregnant females and males of harbour porpoise, Phocoena phocoena (Linnaeus, 1758) along the Rize coast in the Black Sea, Turkey. A total of 68 harbour porpoises (31 males, 22 non-pregnant females and 15 pregnant females) were obtained as bycatch in the turbot gill net fisheries from April 2010 to July 2011. A total of 16 external morphological characteristics of the harbour porpoises were examined by Principal Component Analysis (PCA). the PCA results clearly showed that there is sexual dimorphism mainly in the general size between non-pregnant females and males and also pregnant females and males. the greatest body length in the sample was 142.0 cm for females and 128.0 cm for males. Weight-length relationships (WLRs) of harbour porpoise showed negative allometric growth characteristics (Pauly' t test, P<0.05). the slopes of the regression lines for males, non-pregnant females and pregnant females were significantly different from the isometric growth curve slope of 3 (Pauly' t test, P<0.001). Correlation coefficient (r) was significant for both sexes (P<0.05). These results will enable researchers, fishermen and fisheries management authorities to enhance the knowledge of harbour porpoises life history and ecology.