(the below is an extended version of a blog that appeared online 6 April 2010 at National Geographic News Watch)
During their decades-long lives, sea turtles must endure a ceaseless gauntlet of predators – beaked, toothed, clawed, and thumbed – and human-made hazards like coastal development and plastic trash posing as prey. Unfortunately, even if they succeed in evading these threats, millions of sea turtles worldwide, are unable to avoid falling victim to the most serious, acute threat they face today: fisheries bycatch. The global race to feed a growing global appetite for seafood is causing significant declines not only in fish stocks, but also in accidentally caught species like sea turtles.
I vividly remember seeing the harmful impact of bycatch on one of these magnificent creatures during a nocturnal patrol in Costa Rica a few years ago. With our headlamps flashing erratically and the deafening surf pounding, a team of biologists, park rangers, and volunteers went to work to address a life-threatening condition being suffered by a 500-pound expectant mother. This hulking leatherback turtle, whose sleek, teardrop form mirrored the Milky Way’s brilliance, had an enormously thick bramble of plastic fishing line wrapped around her right front flipper that was greatly hindering her mobility and her ability to make a nest.
We worked quickly. Knives sawing and hands flying about, we cut the line piece by piece until we freed the turtle’s tree trunk-sized limb from the monofilament shackle. Over many days, if not weeks, the line had slowly cut through three inches of skin, muscle, and sinew.
After being freed, the turtle successfully laid her eggs. When she returned every ten days to repeat the feat, we observed that – incredibly – the wound progressively healed to the point that the only vestige of her injury was a pinkish-white scar.
But she was one of the lucky ones.
Countless turtles and other animals fail to escape the threat of bycatch. This occurs when fishing gear accidentally ensnares, entangles, or envelops species that are not the intended catch. In addition to turtles, staggering numbers of marine mammals, seabirds, and sharks – and several million tonnes of non-target fish bycatch – are incidentally captured in fishing operations around the world each year.
In a study released this week in the journal Conservation Letters and led by Conservation International and Duke University’s Center for Marine Conservation, my co-authors and I report on the first global synthesis of all reported bycatch of sea turtles in major categories of fishing gear: gillnets, which are large net-curtains hanging in the water to entangle fish and other creatures; longlines, which string together thousands of baited hooks, usually set to catch tuna, swordfish, and mahi-mahi; and trawls, which are large, bag-shaped nets dragged through the water to scoop up shrimp and anything else in their path.
We tallied all reported sea turtle bycatch from 1990 to 2008, and found that approximately 85,000 sea turtles were caught accidentally in these fishing gears. At first glance, this might seem like a big number – until we consider that typical bycatch reports only cover a miniscule proportion (around 1%) of the total fleet, and most bycatch reports come from large, industrial fishing operations. That means that reports of bycatch in small-scale operations, which account for roughly 99% of the world’s fishers, are essentially non-existent. So in fact, we speculate that the true total of bycaught turtles during this period was not in the tens of thousands, but rather in the millions…at least.
Bycatch is to the world’s oceans what clear-cutting is to tropical forests: It depletes marine biodiversity, weakens ecosystem health and function, and diminishes production of ecosystem services to humans who depend on them. Bycatch reduction – and sound fisheries management more broadly – are paramount to restoring and maintaining robust marine ecosystems. I won’t sugar-coat it though: the scope and variability of the challenges are daunting.
The diversity of fishing gears, configurations and methods in the water today is nothing short of mind-boggling. This enormous variation not only makes bycatch accounting extremely difficult, but it also makes reducing bycatch extraordinarily complicated. If you thought the recently passed US health care reform bill was complex, solving bycatch makes insurance exchanges and Medicare expansion look like child’s play.
But unlike the health care system’s greedy insurance companies, there is no clear bycatch villain to be persecuted and punished. The vast majority of fishers are among the most innovative, hard-working, perseverant people on the planet. They are members of one of the oldest human professions, and by and large, are respectable people who, because of the demands of time and money (time is money to fishers), can’t afford to spend much of either to avoid bycatch while toiling to support their families.
Fishers are also the most valuable resources for us academic biologists because of the lifetimes of knowledge they’ve accumulated making their living on and from the seas. Numerous effective gear fixes to reduce sea turtle bycatch are the result of fishers putting their creativity and expertise to work. Fishers know how their gear works, so they are best suited to design modifications to reduce catch of unwanted species while retaining their targeted catch.
A classic example of a gear fix developed by fishermen that have proven incredible effective in reducing sea turtle bycatch is the Turtle Excluder Device (TED). A TED is a trapdoor that allows big animals like sea turtles, seals to escape from trawl nets, while preventing the loss of smaller-bodied critters like shrimp. When implemented correctly – and this is the key – TEDs work: TED implementation was vital to the recovery of what was once the most endangered sea turtle species, the diminutive Kemp’s ridley, and TEDs are the keystone to the exemplary bycatch management scheme currently employed in Australia’s prawn trawl fisheries.
Unfortunately, gear fixes are not going to solve all of the world’s bycatch problems. Even with encouraging advances in changes in longline hooks or gillnet sizes, the sheer volume of fishing gear in the water means that sea turtle bycatch and most fishing is still, quite simply, unsustainable.
However, fishery managers in some places are applying creative approaches – e.g., catch shares and marine protected areas – which can sensibly manage how marine resources are used and by whom, to build resilience back into marine systems and allow for recovery of fish stocks and protected species. These practices are showing promise where they are implemented properly and with buy-in from fishers.
So what can you and I do to reduce the human ripple effect on our oceans? We can start by becoming educated, responsible seafood consumers. The Blue Ocean Institute offers wallet-sized guides that provide information about how seafood gets from the ocean to the dinner menu, allowing you to decide for yourself what kinds of fishing practices you’ll support. Forgot your wallet guide or haven’t gotten one yet? Send a text message to FishPhone™ (30644) by typing FISH with the name of the seafood item you’re curious about. In seconds you’ll have the knowledge you need to make an informed decision.
Most of us live far away from an ocean, but you and I have an impact by what we put into (e.g. plastic bags, CO2, household chemicals) and take out (e.g. seafood, aquarium pets and coral souvenirs) of it. The oceans provide us with our most basic needs: oxygen, climate, food. They are also home to the most remarkable diversity ever evolved on Earth. Let’s work to be responsible stewards of the breathtaking and wondrous life that still exists on our shared planet.
Eat well. Save a turtle.