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OPINIONS

It takes an ocean to raise a turtle

KAILUA-KONA, HI – By day, I am a lover of microbes. I like to watch them zip around under the microscope, or flash brilliant colors of warning or decoration. When I can’t see them, I imagine the myriad ways they cycle energy and chemicals through the world around me, greasing the wheels of the visible ecosystem.

But by night, I’m a crazed pursuer of what biologists term “charismatic megafauna:” the big, the bold, the beautiful members of the animal kingdom.

And so Li Ling and I found ourselves peering over the railing of a Big Island resort, scanning for a flash of white in the patch of water illuminated by two massive lights. The logic is straightforward: Lighting up a nighttime sea attracts plankton, which in turn attracts things that eat plankton, namely, manta rays.

The giant rays, whose wingspans can easily exceed our own height, are perhaps the most graceful marine creatures I have ever seen. Sharing the water with them is like watching a monochromatic ballet, with perfectly timed spins and turns, delicate wing-flips, and dramatic entrances from a darkened backstage. So when we spotted a diamond of white underbelly in the water, indicating that at least one manta had come to graze at the hotel’s shores, Li Ling and I grabbed our masks, fins, and dive lights and bolted for the rocky shoreline.

Unfortunately, by the time we reached the scene, the manta had retreated back to deeper waters, to continue a lifestyle that even today remains deeply shrouded in scientific mystery.

Later on in our vacation, our wildlife-spotting luck improved: We got close-up time with several moray eels, a zebra-striped nudibranch, nearly a dozen butterflyfish species, and (my personal favorite) a half-dozen green sea turtles.

Though far easier to spot than manta rays (largely because they, like us, enjoy lazing about in warm water or on balmy beaches), sea turtles have a lot in common with the rays. For one, they share a nomadic lifestyle that can take them on journeys lasting hundreds of miles and spanning entire ocean basins. For another, they are iconic, large-bodied, and long-lived. And they are all at risk of extinction.

For both turtles and mantas, troubles began with population losses driven by human appetites.  Members from both groups can be accidentally snarled in fishing lines or nets, and both turtles and mantas have been – and, in some cases, continue to be – fished for food. Recently, manta rays have been fetching high prices in Asian markets: their gill rakers (finger-like projections that help sweep food out of the water they filter at mealtimes) are used in Chinese medicine to boost immune systems, and their cartilage is increasingly used as a filler for shark-fin soup. Just yesterday, however, the United Nations formally prohibited international trade of both species of manta ray, hopefully providing the fish with some relief.

Population recovery, though, is a long, hard-fought battle, particularly for animals with long life cycles. For example, most of the green sea turtles Li Ling and I saw were young, in the midst of their 30-odd-year adolescence between hatching and reproductive maturity. The turtles must survive hazards ranging from shark bites to plastic choking hazards to overly attentive tourists while fattening up on nearshore algae, all before making their first breeding migration – up to 800 miles to the remote beaches of the Northwest Hawaiian Islands. So even though a single turtle nest may produce over a hundred hatchlings, it takes decades to rebuild a decimated population.

Like the sea turtle, most large marine animals are highly mobile. From humpback whales moving from equator to pole, to bluefin tuna traversing the Atlantic Ocean, these movements compound conservation challenges. Fishing rights, shipping lanes, and pollution threats must all be addressed from end to end of an animal’s range. This requires oft-elusive international agreements on management goals, catch limits, and enforcement policies. A huge effort for the preservation of a few charismatic species.

Yet by protecting these species, we also protect their habitat, and the dozens of other organisms – all the way down to my beloved tiny microbes – that utilize it. We also preserve the inimitable experience of drifting among submerged lava rock with a sea turtle, or free-diving alongside a gliding manta ray. And we forge new accords across political boundaries which once had precious little to bridge them.

All because it takes an ocean to raise a turtle. And it takes a planet to save the ocean.

 

Holly welcomes reader questions, comments, and airplane tickets to Hawaii at hollyvm “at” stanford “dot” edu.

About Holly Moeller

Holly is a Ph.D. student in Ecology and Evolution, with interests that range from marine microbes to trees and mushrooms to the future of human life on this swiftly tilting planet. She's been writing "Seeing Green" since 2007, and still hasn't run out of environmental issues to cover, so to stay sane she goes for long runs, communes with redwood trees and does yoga (badly).