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Population size, distribution and behavioral ecology of Indo-Pacific bottlenose (Tursiops Aduncus) and humpback (Sousa Chinensis) dolphins off the south coast of Zanzibar

Lookup NU author(s): Professor Per Berggren



Indo-Pacific bottlenose (Tursiops aduncus) and humpback dolphins (Sousa chinensis) off the south coast of Zanzibar, East Africa, have been subject to both direct andindirect takes as well as disturbance from local dolphin tourism during the last decade. Meanwhile, little or no information on population parameters exists forthese animals. In order to assess the anthropogenic threats, a study was conducted between 1999 and 2002 to determine population sizes, distribution, and behavior ofthese animals. Population sizes were calculated for each year using mark-recapture methods applied to photo-identification data. The estimates ranged between 136and 179 for the bottlenose dolphins and between 58 and 65 for the humpback dolphins in the calculated 26 km2 study area. Patterns in distribution and behaviorwere investigated using image and spatial statistic software on data from boat surveys. Analyses of spatial densities showed that both species concentrated their activities to smaller areas (2%–11.5%) within the study area. When the study results were considered in light of the anthropogenic threats, it was clear that immediate conservation measures were needed. This is critical if the negative impact on the species is to be minimized and the dolphins are to continue to represent a socioeconomic resource in the region.

Publication metadata

Author(s): Stensland E, , Carlen I, Sarnblad A , Bignert A , Berggren P

Publication type: Article

Publication status: Published

Journal: Marine Mammal Science

Year: 2006

Volume: 22

Issue: 3

Pages: 667-682

Print publication date: 01/07/2006

Date deposited: 07/05/2010

ISSN (print): 0824-0469

ISSN (electronic): 1748-7692

Publisher: Wiley


DOI: 10.1111/j.1748-7692.2006.00051.x


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