June 24 rates as one of the highlights in, as I refer to them, the “Sydney Annals of Swimming.”
It all began and ended one early morning, before lifeguards slither in to cause me grief. I sprinted down the steps to the Cove, waded in, waited for my swim buddy, Judith, to catch up, then paddled out to the kelp bed to mix it up with the fronds. It was panning out to be another relaxing, picturesque summer swim, with water visibility of at least 25 feet. I lingered as long as possible, spending an hour-and-a-half sightseeing before heading back to the Cove with Judith in tow. Judith dove down to check out my swimming style, looking up to the surface and, instead of my churning paws and fluffy tail, she was shaken to see a flattened, oval silhouette with four appendages sticking out. Let’s just say it clearly wasn’t me. When she surfaced with opened eyes the diameter of my food bowl, I looked around to see what the ruckus was about. Whoa, that’s one ugly dog, I thought. Its neck and head were bald and wrinkled. The only place that had fur was on its back, and it was, get this, green. Judith and I kept a respectful distance so as not to frighten me—I mean it.
Back on shore, Judith breathlessly relayed our sighting to friends. What we saw was apparently not a dog but a turtle. That’s a relief to dogs everywhere. Here’s what I learned from eavesdropping. The Eastern Pacific green turtle, Chelonia mydas agassizii, is found worldwide mostly in warm waters. It likes to hang out in bays and protected shores, grazing on seagrasses and algae. Maybe we shouldn’t be so surprised to see a turtle in the La Jolla Ecological Reserve because the place is riddled with vegetation.
When turtles hang around a place for a while, algal growth takes hold, and when they distance travel, the growth falls off. No secret itinerary for those. Since that first sighting, we see them occasionally in the area, mostly during the summer. Adult turtles average 2- to 4-feet long and 200 pounds. Our turtle measured about 2 feet across the shell on its back (carapace), which was heavily coated in algae (ah, fake fur).
With a perpetual bumper crop of vegetation, why don’t we see them here all the time? And since they aren’t here all the time, why are they here now? You’ve asked the right dog. After more eavesdropping, I’ve become a font of information. It turns out that for some years now, 30 to 60 green turtles have made up a permanent population that forages in the eelgrass beds in south San Diego Bay by the Duke Energy power plant. The harmless, warm seawater released from the plant likely attracted them, then enticed them to stay. Could it be that the turtles we occasionally see in La Jolla are merely those day-tripping from their South Bay abode?
Who knows but when it comes to studliness, female Chelonias rule. While the males dig their paws into San Diego year round, the females abandon this safety net of sorts to migrate hundreds of miles down the Mexico coastline where they haul out of the water on their favorite nesting beach and bury their eggs in the sand. There may be as many as seven clutches of 80 to 120 eggs each in a single nesting season, which spans from October to March. Interestingly, the temperature of their incubation environment determines whether the resulting hatchlings are girls or boys. Warmer temperatures produce girls, and cooler temperatures result in boys. Once the adult female’s reproductive task is complete, she treks back to San Diego--a journey fraught with peril.
Having a life span of over 50 years would seemingly give these turtles a better shot at species survival but this isn’t so and not only because it takes Chelonia on average 20 years to reach sexually maturity. Every year more than 20,000 greens are killed in Mexico, due to poaching, boat collisions, and drownings (as bycatch in fishers’ nets). Now that they are on the verge of extinction, the U.S. Fish and Wildlife Service recently declared south San Diego Bay a National Wildlife Refuge, making it the only safe haven for these reptiles on both California and Baja coasts. Researchers are using this sanctuary to monitor the green turtles and understand more about their migratory patterns.
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— Judith Lea Garfield, naturalist and underwater photographer, has authored two natural history books about the underwater park off La Jolla Cove and La Jolla Shores. Send comments to firstname.lastname@example.org.