You’ve seen our previous post about two southern sea otters rehabilitated by The Marine Mammal Center in Sausalito, CA, named Otto and Yankee Doodle. Their release on Sept. 22 and Oct. 24, respectively, represented a major milestone, as they were the first two rehabilitated sea otters released back into the wild with LHX life-long monitoring implants (see end of post for more details on LHX tags).
Otto, an 8-year-old southern sea otter, exits his carrier during his release in Morro Bay after being treated for domoic acid toxicosis at The Marine Mammal Center in Sausalito, CA. Video Credit Kathleen Curtis © The Marine Mammal Center, USFWS permit #MA101713-1.
Of course, we want to know how well these two otters are doing after their release! Both animals actually received two implants, one LHX tag, and one VHF radio beacon. This VHF beacon allows researchers to detect their presence and directly track individual animals, using directional antennae and hand-held radio receivers:
Since his release in Morro Bay on September 22nd, Otto has been sighted and detected repeatedly, and appears to be doing quite well in the area.
Yankee Doodle was released on October 24th in Half Moon Bay, near his original rescue location. On October 25th, he was detected and observed in San Francisco Bay. After that confirmed sighting and VHF transmitter detection, he was not seen or detected until just recently: on November 4th he was sighted near Point Reyes by a group of hikers, and his VHF beacon was then detected in an aerial sea otter survey near Point Resistance. The group of hikers posted a video of Yankee Doodle on YouTube:
So far, so good. It is very useful for us to be able to track and observe these animals after their release. Concerns remain about how much these two otters may have been affected by domoic acid, and how this might impact their survival back in the wild. Through the combination of VHF and LHX tags, we are hoping to continue to track them and learn more about how well they will do following rehabilitation.
This is also a good opportunity to remind people not to approach or disturb wild sea otters, or any marine mammal. If concerns exist about an animal that may appear in distress, or if a dead animal is found, please contact your regional stranding hotline.
What are LHX Tags?
LHX tags are a satellite-linked transmitter that is surgically implanted into the abdominal cavity of warm-bodied host animals. They function like a black box on aircraft: throughout the life of the host, they monitor multiple sensors (temperature, light, motion) to determine the state of the host. The tags do not transmit while their host is alive and well – from inside of a body, the signal would be far too weak to reach a satellite. Instead, all this data is stored in memory, and only transmitted to orbiting satellites post-mortem, after the tag has been liberated from the decomposing, dismembered or digested host body. To read up on LHX tags, check out www.sealtag.org, as well as these recent blog entries on 60 North Science: “how we get research ideas,” and “paper in a nutshell” (summarizing a recent scientific paper on the initial LHX tag trials in harbor seal pups). You can read more about Otto the sea otter here, and here you can find a related media release from The Marine Mammal Center.
Written by: Dr. Markus Horning
Otto, an 8-year-old southern sea otter, exits his carrier during his release in Morro Bay after being treated for domoic acid toxicosis at The Marine Mammal Center in Sausalito, CA. The Center serves as the primary first responder for stranded sea otters across its 600-mile rescue range and recently retrofitted several existing pens at its Sausalito hospital to make them a suitable and safe space for the threatened species. Credit Brian MacElvaine © The Marine Mammal Center, USFWS permit #MA101713-1