Monday, March 10, 2008

Franciscana Dolphins - March 10



Final Day of Tagging
Today was the final day to attempt tagging. We did not catch any franciscanas today, but we added several to our photo-identification catalog. In total, we have tagged four dolphins with satellite-linked transmitters. Their positions as of this morning are shown in the attached map, with the red dots being the most recent, and all occurring within the same minute or so. This shows that they are following similar movement patterns, but they are not together in the same group at this time, suggesting perhaps a fluid social structure. More data will be required to document how often individuals join and separate.

The three transmitters with time-depth recoding capability appear to be collecting data appropriately, but limitations of the internet site in San Blas preclude our being able to fully review the data in the field. If they are indeed functioning properly, then we will have accomplished our primary goal for this year´s tagging session.

Killer Whales Spotted
Today we had an added treat - two killer whales entered the bay and passed by our boats. They both had distinctive fins, and we will try to compare them to the existing identification catalog for Argentina. They appeared to be different from the pair we saw here last year - last year's orcas were not in the existing catalog for Patagonia.

Tomorrow will be our last day in the field. We will work with our colleagues from Argentina to refine the photo-ID abilities they have learned working with our Sarasota lab over the past two years, and we will search for distinctive dolphins, our current tags, and individuals tagged last year who should have shed their tags.

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