Biblioteca

Variation in dorsal fin morphology was assessed in five bottlenose dolphin (Tursiops truncatus) populations from the Southeast Pacific. We hypothesized that habitat specialization between coastal and offshore ecotypes led to differences in dorsal fin morphology. Photographs and direct measurements of dorsal fins were used to calculate three indexes: height/length base (h/b), width at half height/length base (a/b) and overhang of the dorsal fin tip/length base (falcateness) (s/b). The sample included 163 individuals (129 coastal and 34 offshore) from Ecuador, 60 individuals (9 coastal and 51 offshore) from Peru and 25 individuals of an inshore form from northcentral Chile (Pod-R). Values were logarithmically transformed to allow one-way ANOVAs and t-tests. Ontogenetic variation was found in coastal dolphins from Ecuador, with indices significantly different among age/classes. All indices were higher in juveniles and calves, suggesting a stronger (allometric) growth of the dorsal fin base (b) than in the upper parts of the fin. Hence only adults and subadults were considered in further analysis.