Potential effect of dolphin-watching tours and other recreational activities on dolphins at Drake Bay, Costa Rica: A case for the spotted dolphin Stenella attenuata (Cetacea:Delphinidae)

P.I. Andrea Montero Cordero

E-mail: amontero@fundacionketo.org

There have been 12 different cetacean species documented in the Osa Península area, between 1979 and 2002. The most frequently observed species is the spotted dolphin (Stenella attenuata). This species appears to maintain a year-round population in Golfo Dulce, a gulf located 60 km south of Drake Bay. Rasmussen et al. (2002), were emphatic about the expansion of resorts and tourist activities in Drake Bay (located in Osa Península) over the last 8 years of their research. The Osa Conservation Area (to which Drake Bay belongs), estimated a total of 88 lodging businesses, from which 48 (55%) are localized along the coast, and own at least one vessel for ecotourism services. These vessels are used to offer tourists whale-watching activities, in addition to or combined with sport fishing, “swim with dolphins”, and diving activities. Unfortunately, most of these companies lack proper training and they seem to be creating constant stressful situations for these species.

Several studies have detected the following changes in cetaceans’ behavior due to whale-watching: horizontal avoidance, increased dive intervals, increased speed and vocalizations. Cetaceans’ spatial distribution is influenced by a number of environmental, biotic and anthropogenic factors, like fishing activity and boat traffic, among others. The sounds created by vessels used to approach cetaceans for science and tourism are problematic since they can cause animals to avoid certain areas, effectively reducing or degrading their habitat.

We also thank: Cabinas Jademar, Emily Tour and Internet Corcovado Expeditions