Preliminary results from skin lesions study in Commerson?s dolphin (Cephalorhynchus commersonii) from the northern Patagonian sea.

M.J. KLAICH, S.N. PEDRAZA, M-F VAN BRESSEM, AND E.A. CRESPO.

Santiago de Chile, Chile,

Workshop; WORKSHOP ON CETACEAN SKIN DISEASES. INTERNATIONAL WHALING COMMISSIONN; 2008

A skin lesion study was carried out in a local population of Cephalorhynchus commersonii from the northern Patagonian Sea, Argentina. Data were obtained from digital pictures taken during seasonal sampling in 2006 and 2007 at the estuarine of the Chubut River. Pictures were classified in four quality levels: bad, regular, good and very good. Only good and very good images were used. We report here on the seasonal and annual variation of prevalence (P) of tattoo skin disease (TSD) and orange marks (OMD) possibly caused by diatoms in this species. Presence and absence of TSD and OMD were recorded for each dolphin. The number of identified dolphins for 2006 and 2007 were 69 and 88, respectively. For TSD and OMD a comparison for P between 2006 and 2007 was carried out by means of confidence interval estimation. The mean annual prevalence levels were 15.43% (TSD) and 4.53% (OMD) for 2006 and 23.81% (TSD) and 11.92% (OMD) for 2007. The P of TSD and OMD showed a significant correlation with time and temperature while the difference between annual P for TSD of 2006 and 2007 tended to be significant. The results obtained during this work will be used to set the basis for a long-term skin lesion study using digital pictures in combination with capture-recapture methods.