April 6 - Franciscana vs. Bottlenose Dolphins

From left to right: Roberto, Lea, and Yaana has moved to the mouth of the bay, where she spent time shortly after she was originally tagged, about a month ago.

Over the past few weeks, Tango (a team member from San Blas who has his own boat) has seen several tagged dolphins while out on the bay, but he was unable to distinguish them by eye. Pablo plans to get a team with a digital camera into the field within the next two weeks to document the tags and identify distinctive individuals.

So, what do they look like? Check out the photo to the right... Franciscana dolphins are very different from bottlenose dolphins (the species that I see and study in Florida---and that you can see at Brookfield Zoo). Adult franciscanas are the size of bottlenose dolphin calves. They have a long rostrum, with hundreds of tiny sharp teeth (as compared to the bottlenose’s short beak with about 100 medium sized teeth). They have a chocolate brown body, matching the color of the estuarine water in which they live. Their eyes are small. Their flippers are relatively large, perhaps reflecting a need for greater maneuverability around features on the sea floor. Franciscana dolphins tend to surface slowly, sometimes with their long beak coming out of the water. I have never seen one jump out of the water.

April 5, 2007

Current satellite information shows that Lea and Roberto are deep within Bahia San Blas, while Yaana is a bit more towards the entrance channel of the bay. Click on the map above for a larger image.

April 4, 2007 - Franciscana Dolphin Range

So...we are going to be posting these maps daily. But you might be wondering what they refer to... You can get a sense of where this place is from the project map below, but what is the area like? Well, Franciscana dolphins live in coastal waters and estuaries---areas where there is influence from rivers, but typically in full seawater. The species is found from Brazil, through Uruguay, to northern Patagonia in Argentina, so the species as a whole experiences a wide range of water temperatures, though more temperate than tropical. This year, we worked near the southern extent of the species’ range, in early autumn waters of about 65 degrees. Where we have worked with them, Franciscans seem to prefer habitats with sandy bottoms and murky waters (from the river influence).

April 3, 2007

Here is today's map. From left to right: Yaana, Lea, Roberto. Click the image for a larger view.