Day 8 - Bottlenose Dolphin Sightings

If possible, it was more than a perfect day, not a cloud in the sky, warm and sunny, and no swells. It was as though the dolphins were waiting for us, because our sightings began within minutes of leaving the harbor. Sean, our fearless captain and founder of the Pelagic Shark Research Foundation, gave his little superstitious tap on the boat’s out drive, which can be detected by the dolphins through the reverberation in water. We spent the remainder of our day surrounded by the pod of bottlenose dolphins. We had over 40 dolphin sightings today, including several mothers and their calves. I had never seen dolphins breach so high, wave after wave, nor ride alongside of boat as well as bow riding. Sean said they were actually watching us and that there hearing is so acute that most likely they recognize the familiar sound of our motor. Breaching occurs when dolphins jump high out of the water and appears to fly up through the surf. Bow riding is when the dolphin leads at the front of the boat and stays ahead within its wake.

We just kept heading south; I could no longer tell whether they were keeping up with us or we were keeping up with them. Anna, was taking a photo ID of as many dorsal fins as possible and broke her record this year with 483 pictures! Sean and Anna were so familiar with this pod that they had given them names from previous encounters and recognizing their dorsal fins. This was definitely part of the Monterey Bay bottlenose resident population as opposed to a transient unit of dolphins that are only present temporarily. Our PI (principal investigator) is exploring the long-term fidelity to a particular area for long periods and maintaining their school structure through time. She is aware of particular “social units” that move back and forth along the coast.
Today, we observed the high cohesion amongst the females, “mothers” with their calves, which was most exciting.
A question for my students to consider now; what is the difference between a resident population as opposed to a transient one?


I would like to credit Peter Nilsson and Anna Janovicz for generously providing many of the awesome dolphin, otter, and whale photographs. Peter and Anna are the team leaders on our Earthwatch expedition.