Dolphin-watching in Península Valdés Argentina: multiway approach for its Management.

DANS, S. L.; DEGRATI, M.; CRESPO, E.A

Setubal

Congreso; 27th. ANNUAL CONFERENCE OF THE EUROPEAN CETACEAN SOCIETY; 2013

Whale-watching in Península Valdés, Argentina, was exponentially growing, showing an annual rate of 14%. This expansion also has lead to the diversification of services. Dolphin-watching emerged as an alternative target in 1997. The activity is still underdeveloped and is based on dusky dolphin groups, during summer, mainly because navigation is forbidden outside this season due to the presence of right whales. The effects of boats on dusky dolphins were already evaluated and several changes in behavior and activity budgets were detected. In this work, several approaches were integrated in order to produce management recommendations: a) the feasibility of rethink the marine protected area based on habitat use pattern, b) the establishment of carrying capacity in terms of energetic costs that the interaction represents for animals, and c) the elaboration of a code of conduct based on ways to minimize behavioral changes. Data were obtained from boat-based surveys and groups followed from 2001 to 2007. Distribution of dusky dolphin groups was analyzed by means GIS tools, in order to test for habitat preferences and temporal variation. Behavioral sequences were modeled by Markov chains and behavioral budget estimated by eigen-analysis as well as its seasonal variation. Eigenvector sensitivity analysis was used for predicting which behavioral changes would produce most significant changes. Dusky dolphins showed preference for some depth and distance to shore categories, however dolphins´ locations changed through years. This result precludes the utilization of a restricted area as a management tool. Feeding activity budget was one of the most affected by boats presence, decreasing from 22 to 15%, Feeding time budget was 11% during winter months when an alternative feeding strategy was observed involving longer-lasting dives. Feeding time budget was more sensitive to the probability of dolphins changing from traveling to feeding, and more less from maintaining a feeding bout.