Seal darting results in three more successful disentanglements

The International Fund for Animal Welfare has been rescuing gray seals for years.

Recently, The Marine Mammal Center’s remote sedation darting and integrated acoustic tracking techniques with California sea lions has proven invaluable in increasing our effectiveness in removing life threatening entanglements from seals in Cape Cod waters.

Months after we successfully rescued our first gray seal using this new method , we were able to disentangle three seals in three days here. I am definitely proud of our team, and our collaboration with the Marine Mammal Center, the Center for Coastal Studies, National Marine Life Center, National Oceanic and Atmospheric Administration and the US Fish and Wildlife Service.

It took 14-18 responders in three to four boats to rescue each of the 200-280 lb. adult gray seals from Chatham harbor. While a high number of seals have life threatening neck entanglements in our waters, we need to target those at the edge of the herd so that we would have a clear shot. Gray seals haul out so close to each other that their bodies are touching, which increases the need for precision targeting with the pressurized dart gun. We aim for a target about 12 inches wide on the seal’s shoulder for an effectual intermuscular injection.

Once darted, we wait approximately ten minutes for the drugs to take effect before we attempt to capture the seal. During that time we follow the acoustic signal from the sedation dart using a hydrophone. This way we can monitor the seal from a distance and be ready to capture as soon as it is sedate enough.

Then we begin the capture process. We were able to catch two of the seals using a hoop net; the third required a seine net. Our team is able to quick switch between capture methods based off of the seal’s behavior and the surrounding conditions. From there we were able to lift the seals onto one of our boats and then bring them to a nearby beach to remove the monofilament netting that was causing injury.

On average this process takes about 45 minutes, including treating and flushing the wound, administering antibiotic and affixing a temporary satellite tag for follow up monitoring and assessment of how the seal is healing.

Earless seals like grays are dramatically different than sea lions. They are better divers, spend more time below the surface of the water, and flush back into the water more easily. These characteristics make hands-on rescue extremely difficult. Luckily we were able to work with other agencies that had figured out some of the techniques with other species and we were able to adapt that.

We are very impressed with how well the seals are recovering after treatment, especially given the severity of the wounds and entanglements.  As long as we can get the entanglement off before the seal becomes too compromised they have a great shot at healing.

It’s amazing to see the before and after results and know that our team is making a difference to save individual seals that would otherwise die a slow and painful death. One of the program goals is to use the information we learn from these disentanglements to figure out how to prevent these entanglements in the first place. We are also gathering significant data about individual seals, which is expanding the knowledge of gray seal behavior and habitat use for the population at large.

Our goal is to further refine the techniques so that we can rescue multiple seaIs in one day. We are also talking with our international partners to replicate these techniques to help save various seal species around the world.


All activities were performed under NMFS permit #18786 and supported in part by a John H. Prescott grant. For more on the NOAA Marine Mammal Health and Stranding Response Program, click here

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Azzedine Downes,IFAW President and CEO
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Beth Allgood, Country Director, United States
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