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The Disappearing Ocean Travelers
By Peter Winch
Last November I was working as a naturalist on a wildlife watching trip to the Farallones. We hadn’t had the best day for wildlife—a few humpbacks in the distance, a couple of harbor porpoises.
On our way back, the boat drifted through thick patches of fog, then out into areas of limited visibility, then back into fog again. Pink-footed and sooty Shearwaters skimmed across our bow, and when the mist cleared the sunlight cast an ethereal glow on the ocean.
Then I saw it. A leatherback turtle.
A thick, stumpy neck rose from the water, and the curve of the black shell behind it. A moment later, the turtle slipped back into the fog. I notified the skipper and we turned around, criss-crossing the area for ten minutes, until we spotted it again.
The turtle would dive for 3 to 5 minutes before emerging again to breathe, its ridged back breaching like a dinosaur. A leatherback is a big animal, the largest sea turtle in existence. The biggest specimen ever recorded was on a beach in Wales; it was three meters long and weighed over 2,000 pounds.
After 15 minutes of sensitive observation, we left the area thrilled at this rare encounter with one of the most endangered reptiles on the planet.
Last month, a dead leatherback washed up at Fitzgerald Marine Reserve in San Mateo. The cause of death is currently unknown; however, it is a distinct reminder of the species’ delicate future.
The Pacific population is divided into two sub groups. One population nests on the beaches of Indonesia, Papua and the Solomon islands. This population migrates to waters off California, including the Gulf of the Farallones National Marine Sanctuary. Our Sanctuary has an abundance of their favorite food, jellyfish. This 3,000 mile plus migration is an incredible feat of navigation.
The second population nests on beaches off Costa Rica, and migrates south to coastal waters off South America for food.
The leatherback sea turtle is a listed Endangered Species. The world population of nesting females is estimated at between 26,000 and 43,000 individuals, of which most reside in the Atlantic population. The Pacific population has declined exponentially in the last 30 years, and the Indonesia/Papua population that frequents our waters is estimated at possibly only 600-650 females. Some believe this group will become extinct in the next 25 years.
There were other significant populations that nested in Malaysia, India and Mexico which are now thought to be extinct or 1% of their numbers in the 1950s.
What caused this decline?
Egg collection and loss of habitat are thought to be the main causes of their decline since the 1950’s, especially in India and Malaysia.
Their eggs are prized in these parts of the world.
Coastal development on their nesting beaches has meant loss of habitat, and light pollution from humans causes nesting turtles to become confused (they are thought to navigate partly by the sun and moon). This significantly disrupts their reproductive effort.
Egg collection sadly remains a threat to existing populations, but other threats at sea pose serious problems to these ocean-faring animals. Adult leatherbacks are caught as a bycatch in many of the worlds fisheries, including long-lining, gill netters and drift netters.
Plastic pollution is also a cause of leatherback mortality. A clear plastic bag floating in the water is difficult to distinguish from a jellyfish. Ingestion of plastic has accounted for a number of leatherback fatalities, either from asphyxiation or intestinal damage.
Extinction is a very real threat for the leatherback sea turtle, especially the Pacific population.
Here is what you can do to protect these ancient creatures:
1. Reduce your consumption of plastic and dispose of the plastic you do use in an appropriate place.
2. Be selective and informed about what fish you eat. Choose local fish from sustainable fisheries caught using the least destructive fishing techniques.
3. Research sea turtle conservation groups. The Sea Turtle Restoration Project is an awesome non-profit based in Marin that has ties with Sea Turtle Conservation projects worldwide.
4. If you are a boat user in local waters, researchers are in need of data on any leatherback sightings. Contact Scott Benson, the NOAA Research Fishery Biologist, Protected Resources Division, who is studying leatherback sea turtles off central CA waters. His email is Scott.Benson@noaa.gov
5. Heather S. Harris (email@example.com) also collects information for the Marine Mammal Center. Latitude and Longitude of the sighting is greatly appreciated as are photographs and behavioral observations.
Please join FMSA on one of our monthly whale watching trips out to the Farallones. Fall is a good time to try and see these remarkable reptiles. No guarantees. The magical presence of leatherback sea turtles in our Sanctuary is sadly an increasingly rare event.
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