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Release Criteria

Here are some commonly asked questions about release back to the wild criteria at The Marine Mammal Center.


1. Does the Center release animals at the location from which they were rescued?

No, we do not usually release animals at the location from which they were rescued. Often the rescue sites are public beaches, which are not good release points. Other animals are rescued from places that are very inappropriate for them such as docks, sidewalks, roads, porches, carports, and even airport runways. Marine mammals are migratory animals and are capable of swimming large distances, so it does not affect them to be released at a different point within their range.

2. Where are animals released?

The majority of animals are released at a quiet, non-public beach at Chimney Rock in Point Reyes National Seashore, Marin County. Occasionally, we release animals at other locations such as Anchor Bay Campground, Mendocino County; Fitzgerald Marine Reserve, San Mateo County; Point Lobos State Reserve, Monterey County; or Leffingwell Landing, San Luis Obispo County. At times, we release young California sea lions that have become accustomed to human contact and northern fur seals that are pelagic, out near the Farallon Islands via boat. Using remote release sites ensures that the released animals will have a quiet beach away from humans on which to gradually reenter the wild. In addition, there are seal and/or sea lion haul out areas in close proximity to these release locations.

3. What are your release criteria?

Prior to release, a veterinarian must give animals a clean bill of health. Stable body weight and blood chemistry and hematology values within normal parameters are also required. The animals must also be free-feeding, that is, able to eat fish on their own. Pups and vision-compromised animals must be capable of tracking and eating live fish.

4. What does the Center do with animals that cannot be released?

Although the Center's ultimate goal is to release animals back to the wild, occasionally we will have an animal that is non-releasable. Animals that we have designated as non-releasable have included a sea lion with epilepsy, a northern fur seal that was hit by a car after coming ashore in Berkeley, and a harbor seal pup that suffered brain damage after being illegally picked up from a beach by unauthorized people who allowed him to get overheated. We try to place these animals in licensed zoos or oceanaria, where they will be cared for properly and will be with others of their species. Occasionally, the Center has also served as a refuge for captive animals being transferred or placed in another zoo or aquarium. The length of stay for these animals depends on how quickly a zoo is found that will take them, and how quickly all the appropriate permits are approved and funds for the transfer are gathered. By transferring these non-releasable animals to zoos and oceanaria, we are helping ensure that these animals are given a comfortable home, and fewer animals are collected from the wild populations for captivity. The animals also provide an opportunity to educate the public about marine mammals.

5. How does the Center follow up on released animals?

All released pinnipeds (seals and sea lions) are tagged on their flippers with numbered orange plastic tags, registered at the Center and with the National Marine Fisheries Service (NMFS). Local biologists and marine mammal observers report tag numbers for released seals and sea lions that are resighted in the wild back to NMFS and the Center. NMFS permittees use tags of different colors. Año Nuevo researchers use green tags, Farallons researchers use pink tags, San Miguel Islands researchers use red tags, and so on. Orange is the color used by California rehabilitation centers like the Center.

6. What percentage of rescued animals are released back into the wild?

Through effective assessment, triage, and monitoring processes, the Center only admits animals that are sick or injured and in need of medical assistance. Survival varies by species, but overall approximately half of the animals admitted are released back into the wild.

7. Are pups released by the Center able to fend for themselves?

Such concerns are very valid at a rehabilitation center. We try to prevent the pups from becoming tame by taking several precautions. Contact with the pups is kept at a minimum; unnecessary handling is not allowed, such as cuddling or pampering. Hand-feeding is practiced only until the pup learns to grab its food from underwater. Keeping several pups together in the same pen promotes socialization with each other and not with people. The Science Department has placed radio tags on some harbor seal pups before release in order to monitor their behavior in the wild. We have located many tagged harbor seals, hauled out and healthy six months to a year after release.

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