Satellite tags show Risso’s dolphin’s far-ranging movements since release

This map and dot chart shows the movement of a Risso’s dolphin after its release in January.


The following blog was written by our stranding apprentice Katherine McKenna. –MN

Each day, we have been eagerly checking the satellite tag data of a unique dolphin we rescued here on Cape Cod last month.

Map data shows that it travelled around Cape Cod Bay before moving offshore to Wilkinson Basin, then toward the Great South Channel, even further offshore.

Now more than three weeks later, is has swum all the way out to the edge of the continental shelf, over 110 miles from the beaches where it had stranded.

This case was truly remarkable as it represents the first time that a Risso’s dolphin has been successfully rescued, satellite tagged and immediately released from this region. These data not only signify a positive sign for this dolphin, but also provides post-release tracking data that will be invaluable for future live cetacean responses.

On Sunday January 17th we received a late afternoon hotline report of a live dolphin stranded in Loagy Bay, Wellfleet, one of our biggest hotspots for cetacean strandings. Despite losing daylight and the tide incoming for the next hour, we began to pack our trailer with gear to respond. The caller’s description of the dolphin did not match up with the dolphin species to which we commonly respond so we anxiously awaited photos to help identify the species.

Once photos were received we were able to confirm it was a Risso’s dolphin, a species typically found offshore in deeper waters.

Our five person response team, three IFAW staff and two volunteer responders, met at the stranding site in Wellfleet with all of the equipment we would need for the rescue. We walked through the rain in tall marsh grass to reach the dolphin which had been completely out of the water as the tide continued to recede. The dolphin was quite calm considering it had likely stranded during the morning high tide before being found later in the day.

When responders reached the dolphin, it was quite calm considering how long it had been likely stranded.

Our two volunteers stayed with the dolphin monitoring behavior and respirations while the trailer was prepped. With help from several members of Americorps Cape Cod, whom we had trained months before as responders, we loaded the nearly 9-foot-long, 450-pound dolphin onto a cart and transported it into the trailer.

Once inside the trailer the dolphin received supportive care and a health assessment which included drawing blood for diagnostics, monitoring behavior and respirations and an external exam for any injuries or wounds. In addition to their tall dorsal fin Risso’s dolphins have a distinct appearance from the white scars that cover their gray body. These scars accumulate over time and are the result of social interactions with other Risso’s or from when they hunt prey.

The dolphin we had rescued had minimal scarring which, along with its smaller size, led us to believe it was a subadult dolphin. After a consult with our veterinarian it was decided that we would release the dolphin with a small identification tag on the dorsal fin as well as a temporary satellite tag that would enable us to monitor the dolphin’s movements post-release.

Once we arrived at Herring Cove, Provincetown, the closest suitable release site, the tags were placed onto the dorsal fin and the dolphin received pre-release treatment before being loaded back onto the cart. At around 10:30 PM we carried the dolphin in a stretcher off the cart and into the water. As we ventured deeper into the water we all kept looking back at its tail to see if there was any movement of its fluke. Although it took a while to get acclimated to the water, we became hopeful when we saw a slight tail flutter. The stretcher was then removed and we carried the dolphin in deeper before letting it go. At first the dolphin rolled to its right but then gave strong tail motions before heading offshore until we could no longer see it through the swirling snow.

With a sigh of relief we packed up and headed back to our warehouse, anxious to see what the satellite tag tracks would show. We’ve been checking nearly every morning since that day.

This rescue and release would not have been possible without a great team effort, and I’m honored to have been a part of this memorable response.


Activities conducted under a federal stranding agreement between IFAW and NMFS under the MMPA.

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Senior Program Advisor
Senior Program Advisor
Brian Sharp, Emergency Relief Officer, Stranding Coordinator
Manager, Marine Mammal Rescue and Research
Céline Sissler-Bienvenu, Director, France and Francophone Africa
Director, France and Francophone Africa
IFAW Veterinarian
Katie Moore, Deputy Vice President, Conservation and Animal Welfare
Deputy Vice President, Conservation and Animal Welfare
Loïs Lelanchon, Animal Rescue Program Officer
Animal Rescue Program Officer
Shannon Walajtys
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Vivek Menon, Director of IFAW partner, Wildlife Trust of India
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