San Diego Bay Sea Turtles

Their origin remains a mystery, but South San Diego Bay is home to a group of green turtles (Chelonia mydas), also known as black turtles. Sea turtles have been sporadically reported in San Diego Bay since the 1850's. During this time it was common for commercial fisherman to harvest turtles from Mexican waters and bring them to canneries located in San Diego Bay. Turtles that were being held in corrals before slaughter would regularly break out and escape into the bay. Thus, many believe this may be how the population of turtles in San Diego Bay was established.

Although they do not venture ashore this far north to nest, green turtles are often found during the summer months in waters off the coast of California, Oregon, and as far north as Alaska. Usually the turtles will stop feeding and eventually die if caught in cold waters. However, in the southern part of San Diego Bay the water is warmed by thermal effluent from the Duke Energy power plant, and supports a small population of green turtles year-round. The area near the Duke Energy power plant is the only area on the west coast of the United States where green turtles are known to aggregate (Stinson 1984). They appear to thrive there, although several turtles have been killed by boats in different parts of the bay. In addition to turtles, the wide variety of fish and birds that inhabit South San Diego Bay (including a number of endangered species) have led to a proposal by the U.S. Fish & Wildlife Service to designate South San Diego Bay as a National Wildlife Refuge.

Green turtles in the eastern Pacific Ocean are considered endangered throughout their range. Major threats to these turtles include: habitat destruction, incidental capture in commercial fisheries, and harvesting (often illegally). South San Diego Bay may be one of the few “safe” sanctuaries in the Eastern Pacific Ocean because there are fewer of the above mentioned threats

The Marine Turtle Research Program at Southwest Fisheries Science Center regularly monitors green turtles in San Diego through biological sampling, sonic tracking, and satellite telemetry. Biological sampling provides not only physical data about the turtles such as weights and measurements, but also involves using skin and blood samples for analyses by our Molecular Ecology Laboratory (link). These data are used worldwide in genetic and isotope studies conducted at our lab. Sonic tracking allows us to track the turtles’ movements throughout the bay. We have a collaborative work with the Port of San Diego and NAVY to investigate movements of green turtles in San Diego Bay. Occasionally, we attach satellite transmitters to turtles, allowing us to determine where the turtle is traveling by sending a satellite signal each time the turtle surfaces.

First a turtle is caught in the net, then it is pulled into the boat so it can be brought to shore for research.

photo: Lindsey Peavey

There are approximately 60 green turtles that inhabit in San Diego Bay. The largest turtle ever that measured by our group was 110.0 cm (that’s 3.6 feet) and weighed 240.0 Kg (that’s about 530 lbs!!), which probably is the largest known green turtle in the Eastern Pacific.

The Marine Turtle Research Program at the Southwest Fisheries Science Center is also interested in education and outreach. In the past, we have teamed with Ocean Planet Research to provide interested students and community members with opportunities to assist in the conservation research being done with sea turtles. Ocean Planet Research is a non-profit organization dedicated to raising funds for sea turtle conservation and providing unique educational opportunities for those interested in sea turtles.

What Can You Do To Help?

Check out Ocean Planet Research’s website for ways that you can help sea turtle conservation.

Other links for information about sea turtles include:
www.seaturtle.orgThe previous link is a link to Non-Federal government web site. Click to review NOAA Fisheries disclaimer
www.wildcoast.netThe previous link is a link to Non-Federal government web site. Click to review NOAA Fisheries disclaimer
www.turtles.orgThe previous link is a link to Non-Federal government web site. Click to review NOAA Fisheries disclaimer

What Outreach/Educational Activities Are Available?

Turtle Talks

Scientists from the Marine Turtle Research Program are available to give a variety of talks about sea turtles to K-12 classrooms, camp programs, or local clubs. Some examples of turtle talks are: San Diego Bay Green Turtles, Using Genetics to Study Sea Turtles, Using Radio and Sound Waves to Track Sea Turtles, General Sea Turtle Knowledge. Our talks can be geared to a wide variety of ages and groups.

**There are many opportunities for educators to get their students involved in sea turtle conservation. Please contact Robin LeRoux at if you have any questions regarding any programs or activities. For other related fishery talks please contact Rosemary Troian at

Sea Turtle outreach at the San Diego International Airport.

photo: Peter Dutton


Weighing a turtle.

photo: Lindsey Peavey

Measuring a turtle.

photo: Lindsey Peavey

This turtle has both a satellite and a sonic transmitter attached to it.

photo: John Dutton

Two green turtles with sonic transmitters near the Duke Energy power plant in south San Diego

photo: John Dutton

A Green turtle, up close and personal

photo: Lauren Hansen


Heading back to the water after biological sampling and sonic transmitter attachment.

photo: Lauren Hansen

Check out the size difference between an adult male and a juvenile!

photo: John Dutton