Patterns of associations among fin whales (Balaenoptera physalus) observed in Gulf of St-Lawrence, Canada

Abstract:

Little is known about the social organization of balaenopterids . Fin whales are typically seen alone or in pairs but larger groups occur in some areas. We analyzed fin whale photo-identification and biopsy data collected in the northern Gulf of St. Lawrence (GSL), Canada. 2068 sightings (out of 3608) contained at least one identified fin whale; 286 fin whales were identified (61 males; 64 females). Observed group sizes ranged between one and 18 individuals and were among the largest reported for fin whales. Females were significantly more likely to be seen alone than males. 57% of pairs were mixed, but male biased sex ratio was evident in all larger group sizes sampled. Mean associations indices (MAI) were twice as high for males as for females . Similarly, male-male MAI were twice as high as male-female and three times as high as female-female MAI. Permutation tests provided evidence of short-term association among males, females and between males and females but there was no evidence of long-term associations. Standard lagged associated rates indicated some long-term associations between males and females.

Delarue, Julien; Bérubé Martine; Ramp, Christian; Sears, Richard. 2009. Patterns of associations among fin whales (Balaenoptera physalus) observed in Gulf of St-Lawrence, Canada. Poster presented at the Eighteenth Biennal Conference on the Biology of Marine Mammals, Quebec, Canada.
Patterns of associations among fin whales (Balaenoptera physalus) observed in Gulf of St-Lawrence, Canada PDF (548 KB)