Dolphin Release
DB: This is Earth and Sky. Releasing a captive or trained dolphin back into the wild is far more difficult that it might seem – if you want the animal to survive.
JB: Most of the time, dolphin releases don’t work. Emaciated dolphins show up in harbors, begging for food from boats and people. But there’s one well-documented success story. Two male bottlenose dolphins, Echo and Misha, were released from the Mote Marine Laboratory into Florida’s Tampa Bay in October, 1990. A decade later, they’re still alive and at sea.
DB: There are some good reasons why this experiment succeeded where so many other attempts failed. Misha and Echo spent only two years in captivity. They were collected from the wild when they were six or seven years old – old enough to have learned to catch fish and avoid predators. But perhaps the most critical contribution to their survival was that Misha and Echo were returned to the same waters from which they were captured. These dolphins already knew the available prey, predators and environmental patterns in their familiar home range.
JB: Misha and Echo re-integrated themselves into long-term social relationships that make up the fluid dolphin society. Since their release, they’ve been observed with some of the same dolphins they were seen with prior to their capture. Special thanks today to the National Fish and Wildlife Foundation and to the U.S. Forest Service. We’re Block and Byrd for Earth and Sky.
The following individuals were interviewed for today’s program. Our thanks to:
Trevor R. Spradlin
National Oceanic and Atmospheric Administration
National Marine Fisheries Service
Office of Protected Resources
Silver Springs, MD
Randall S. Wells, Ph.D.
Chicago Zoological Society
The following books, articles and web sites were used in preparing this script:
McClintock, “Baywatch”, Discover, Volume 21, Number 3 (March 2000)
Wells, R.S., “Sarasota Dolphin Research Program Enters 30th Year”, Mote News, Vol. 44, Number 3 (Fall 1999)
Wells, R.S., K. Bassos-Hull and K.S. Norris. 1998. Experimental return to the wild of two bottlenose dolphins. Marine Mammal Science 14:51-71.
Author’s Notes:
It’s difficult to say how many released dolphins have survived in the wild. Many releases have not included systematic follow-up monitoring as part of their release protocols. In these cases, monitoring has relied upon receiving (largely unconfirmed) reports from the public. Thus, reliable documentation of successes has been minimal. With the Misha and Echo project, as well as with the rehabilitated stranded dolphins that released from the Dolphin and Whale Hospital at Mote Marine Laboratory, researchers have tried very hard to implement appropriate follow-up tracking and/or observation efforts in order to monitor their re-adjustment to life in the wild, and, under appropriate circumstances, to be able to intervene if the animals indicate a failure to thrive. This monitoring is the only way to get hard data to address the kinds of questions you pose.
The methods that researchers use to track dolphins when they are returned to the wild depend on the species and habitat. Scientists expected Misha and Echo to remain in inshore waters, as these are patterns exhibited by other dolphins within the same region, and they already had indications of long-term residency by Misha prior to release. Therefore, scientists were prepared to observe them frequently from small boats. In order to track the dolphins, they placed a small radio transmitter on Echo’s fin that was designed to fall off within a few weeks, and conducted photographic identification surveys through the waters of Tampa Bay to search for the dolphins and to document their condition and associates. Researchers conducted conducted focal animal behavioral observations on the dolphins over the first year following release. Each dolphin had a distinctive dorsal fin. In addition, freezebranded numbers were placed on their bodies and fin, primarily for the benefit of other observers who might be able to report sightings.
