Movement and behavioral patterns of bottlenose dolphins, Tursiops truncatus, related to tidal regime at San Antonio Bay Marine Protected Area, Patagonia, Argentina

GUILLERMO M. SVENDSEN; GONZÁLEZ, RAÚL A; RAMÍREZ, AGUSTINA; COSCARELLA, MARIANO; ROMERO, MARIA ALEJANDRA

Rio Grande

Workshop; II Workshop sobre la Investigación y Conservación de Tursiops truncatus en el Atlántico Sur Occidental (ASO); 2017

Universidade Federal do Rio Grande

In response to a multispecific diet, bottlenose dolphins have developed unique foraging techniques and strategies, adapting to the local environment. In Patagonia, groups have been observed moving along with tidal currents while feeding, their displacement being towards the coast on high-tide periods, as occurs in San Antonio Bay (San Matias Gulf, Argentina). Therefore, this work aims to describe the behavioral pattern of bottlenose dolphins associated to tidal dynamic inside the bay and in its surrounding area, under the hypothesis that dolphins feed inside the bay while moving in advantage of the direction of the currents. Using binoculars, continued focal sampling was carried from a strategic point on the coast allowing a wide-range view of the inner side of the bay, recording data on behavior, group composition and tidal state. Furthermore, future analysis will be carried on historical data of sightings as well, on both cases studying frequency and occurrence of feeding events as a function of tidal flow, type and size of group, depth, season and exact location on the sampled area. Surveys from 2016 resulted in 21 focal sampling of a total of 25 sighted groups (ranged from 2 to 15 individuals), lasting from 3 to 45 minutes. The presence of dolphins in the bay increases during high-tide periods, and it has been possible to observe groups following the movement of the tide, feeding events and events related to this state. Thus, we expect to contribute to the knowledge of foraging strategies of this species in the ASO, taking into account that it will provide valuable information useful for conservation of this species, as human activities on marine environment keep on growing in San Antonio Bay.