Abundance of dolphins in the southern Egyptian Red Sea

Le résumé fourni par la source

Cetaceans in the Red Sea are poorly known and the lack of information on species presence and abundance is precluding assessments of population status. This work reports the first abundance estimates for delphinids in the southern Egyptian Red Sea based on vessel surveys. Three surveys were conducted in summers 2010, 2011 and 2012 using conventional distance sampling techniques covering a study area of 10,651 km 2 . A total of 3,702 km were searched on transects (sea conditions Beaufort ≤ 5) resulting in 81 sightings of five species. The following abundance estimates and coefficient of variation were obtained for these species: S. attenuata 8,146 (0.26), S. longirostris 6,609 (0.24), T. truncatus 407 (0.36), T. aduncus 497 (0.49) and G. griseus 303 (0.34). Detection probabilities were estimated for groups of combined species due to limited sample sizes (S. attenuata + S. longirostris; Tursiops sp.; Stenella sp. + G. griseus) and as function of covariates likely influencing the detectability. The abundance estimations obtained are the essential first step in developing conservation measures for cetaceans in the area as recommended by the Regional Master Plan developed by the countries of the Red Sea region in 2002.

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