Andrea Montero-Cordero

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)

Drake Bay.

Town/RegionCountryCategoriesDate
Drake BayCosta RicaCentral and Latin America, Cetaceans, Mammals21 Jan 2005

There are 11-12 different cetacean species documented for the Península de Osa area, between 1979-2002, where the most frequently sighted dolphins are spotted dolphins (Stenella attenuata). This species appear to maintain a year-round population in Golfo Dulce, a gulf located 60 km south Drake Bay. Rasmussen et al., were emphatic about the expansion of resorts and tourist activities in Drake Bay (located in Península de Osa) 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 permanently, or in an opportunistic way, to offer tourists whale-watch activities, in addition or combined with sport fishing, swim with dolphin, and diving activities. Unfortunately, most of these companies lack proper training and they seem to be creating constant stressful situations to these species.

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

Project Update: October 2007

In order to asses the potential effect of dolphin-watching in Bahia Drake (8°41' N and 83°40' W.), Costa Rica, a 2 year study was initiated in December 2004-April 2005. The observations were performed from a 7m boat with a four-stroke outboard engine. Data on the number of boats within 300m of the group of dolphins and dolphins’ behaviour was collected, in addition to dolphin group size and age class composition.

Behavioural observations were recorded using a scan-sampling method, where the groups’ activities were registered every 2 minutes. Acoustic recordings were performed simultaneously. Spotted dolphins’ sightings averaged 5±2.5 sightings/day and 90 sightings/season. Throughout the season, the apparent main behaviour showed by spotted dolphins is feeding.

Besides spotted dolphins, other 3 cetaceans’ species were observed in presence of more than one boat: bottlenose dolphins (Tursiops truncatus), false killer whales (Pseudorca crassidens), and humpback whales (Megaptera novaeangliae). Two community meetings have been done in Drake Bay, and we expect to have more during 2005 and 2006.

Final Report

Read about the activities undertaken and findings of this project in the final report below.

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Detailed Final Report82 KB

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