Posted by: carlsafina | Saturday, October 20 07

Loggerheads in the Headlines

When I was writing my book “Voyage of the Turtle,” my focus was on the sumo wrestler among sea turtles, the gigantic Leatherback that can weigh a ton. But through my travels, concern about another species, the Loggerhead Turtle, also kept recurring.

Two recent publications merit attention: 1) a new five-year global review of the Loggerhead Turtle by the U.S. government, and 2) a new paper about incidental catch of Loggerheads in Pacific Baja, Mexico, by Hoyt Peckham and several academic colleagues. [see: www.fws.gov/northflorida/SeaTurtles/2007-Reviews/2007-Loggerhead-turtle-5-year-review-final.pdf AND www.plosone.org Search there for: S. Hoyt Peckham, David Maldonado Diaz, Andreas Walli, Georgita Ruiz, L.B. Crowder, and Wallace J. Nichols, Small-scale fisheries bycatch jeopardizes endangered Pacific Loggerhead turtles. PLoS ONE]

When I started going offshore frequently off Long Island in the 1980s, Loggerhead Turtles were in decline. But in the 1990s, their nesting numbers rose considerably on U.S. east coast beaches. In South Florida, for example, Loggerhead nesting populations had grown about 4 percent per year in the 1990s.

Loggerhead populations worldwide have serious problems from fisheries and beach development. The Southeast U.S., from Texas to the Carolinas and especially Florida, has one of the two largest Loggerhead nesting populations in the world. (Oman, on the Arabian peninsula, has the other major nesting area.) The U.S. population has become the most important globally because it probably has the highest remaining population and the best chance for good future management. Yet recent figures show that the Loggerhead population is declining by about 4 percent each year, erasing the gains of the 1990s. Elsewhere on the U.S. coast they’re dropping between 2 and 7 percent annually.

But does that decline really mean much? I used to think not. But now I’m getting concerned.

When I visited the Southeast U.S. in 2004, I saw plenty of Loggerheads. They were near their recent nesting peak and had just started the downturn that everyone is now talking about. In the water, in the right places, juveniles not yet old enough to breed abounded.

The analysis then was that adults were declining because their numbers reflected conditions 25 years or so earlier—when they were hatched. During those bad old days, beach protections were so poor and fisheries mortality were high for so many years that few Loggerheads survived to adulthood. This left a “hole” in the population, leading to a predictable decline in nesting numbers. According to this analysis, the problem wasn’t so much that older turtles were dying, but more that there were so few young ones from decades earlier to mature and replace them. So, the population was dropping.

But because of increased protections for nests and from fisheries, the number of juveniles in the water skyrocketed in the ‘90s. And because fisheries and beach protections were still improving in 2004, there didn’t seem much to worry about. Mandatory turtle escape (or excluder) devices were largely successful in shrimp nets.
Bycatch pile

Even where fishing boats must use turtle escape devices, shrimp nets catch and waste many unwanted fishes

Surviving juvenile turtles that were benefiting would begin maturing in ten to twenty years, filling in the ‘hole’ in the declining adult population.
Researchers release a juvenile Loggerhead off South Carolina
Researchers release a juvenile Loggerhead off South Carolina

At least, that was the hope. I shared that hope and still do. Shrimp and longline fisheries now kill far fewer turtles than they did, and many beaches do have better protection than in the past.

Loggerhead in researcher’s net.

Loggerhead Turtle in researcher’s net. Many still drown in some fisheries.

But what if that’s wrong? There’s at least one other possibility: the number of juveniles reflects better protection of beaches and nests, but the falling number of adult nesters indicates that the fisheries kills remain too high for the population to absorb. In other words, yes, there are a lot of juveniles, but they’re not surviving long enough to reproduce and increase the species’ population.

If that’s the case, we’ve got a problem. And what might that problem be? The federal report called fisheries the “most significant man-made factor affecting the conservation and recovery of the Loggerhead.” So, while we make sure the beaches remain as secure as possible, the hole we have to fix is the old fishing hole. All fisheries, not just some, should be required to use the modified nets and modified hooks proven to avoid most incidental catch of turtles.

It’s not easy being a sea turtle. Loggerheads take about 25 years to mature. Then females come out on certain beaches to lay eggs. The eggs must survive undisturbed for two months or so, and then enough of the cookie-sized hatchlings must survive every appetite and hazard of the natural ocean, plus nets, fishing lines, plastics and pollutants for another quarter century before big females in their 200-pound prime come back to do it all again—if the beach is still there and not overrun by hotels, condos, and arcades.

Now let’s skip to the Pacific side of Mexico. Baja, to be specific. The new study by Peckham and his co-workers highlights something long suspected, never well studied. It’s the tip of many icebergs.

Their study looked at two small fishing villages and their turtle catch—mostly Loggerheads. I was there briefly a few years ago and got a first-hand look at the boats, fishermen, and gear. They use narrow open boats about 22 feet long with an outboard motor. They have no GPS, no radios. They set and pull their gillnets by hand. It’s hard, hazardous work, and no guarantee of long life.

Until this study, virtually all the fishing-related mortality that had been documented was in industrial-scale trawl (dragged-net) and longline (miles-long line with thousands of hooks) fisheries. Hundreds of thousands of turtles are caught this way, and many of them are killed (see: Lewison, R. L, S. A. Freeman and L. B. Crowder. 2004. Quantifying the effects of fisheries on threatened species: the impact of pelagic longlines on Loggerhead and leatherback sea turtles. Ecology Letters 7: 221–231.)

But Peckham’s team notes that small-scale fisheries employ 99% of the world’s 51 million fishers, and their activities go largely unmonitored and unregulated.

Peckham and Co.’s main finding was that the two fishing villages they studied fished in areas also preferred by Loggerheads, and caught at least 1,000 Loggerheads yearly. Their catch rates rival those of industrial-scale boats.
Small-scale nets also tangle turtles in Baja

Small-scale nets like these also tangle turtles in Baja

And those two Mexican villages help threaten the entire Pacific Loggerhead population for the following reason: all the Loggerheads off Mexico come from Japan—their only North Pacific breeding area—where the breeding population has dropped 90 percent in the last several decades. About a thousand breeding females remain. Juveniles concentrate in a couple of places in the North Pacific, but many cross all the way to Mexico, then stay for a couple of decades until they mature and head back to Japan. Everywhere they go, they meet nets and lines. Sometimes, they meet their death.
A Loggerhead drowned in a fishing net washes ashore in Baja
A Loggerhead drowned in a fishing net washes ashore in Baja.

Off Baja, a fisherman working a couple of nets from a small boat sometimes drowns more than a dozen turtles a day. Discarded turtles then wash ashore, and the local beach, as I described in “Voyage of the Turtle,” is a carnival of carcasses.

A Loggerhead mummified by the blowing salt and sand of Baja

A Loggerhead mummified by the blowing salt and sand of Baja

The good news? Because the scientists worked cooperatively with the fishermen and spent years building trust, a consortium of local people are working to eliminate their catch of turtles, and to establish a national Loggerhead refuge. Bravo.

—Carl Safina

To read the scientific report: http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0001041
For more information, contact these authors of the paper:
Lead author Hoyt Peckham: hoyt@BIOLOGY.UCSC.EDU
Regarding turtle conservation in general – J Nichols: jnichols@oceanconservancy.org
For inquiries about graduate studies in turtle research and the Duke Marine Lab, Dr. Larry Crowder: lcrowder@duke.edu

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Responses

  1. Thank you, Carl Safina, for “Loggerheads in the Headlines” (Oct. 20, ’07). Your information about Loggerheads, as follows, is heartening: “The good news? Because the scientists worked cooperatively with the fishermen and spent years building trust, a consortium of local people are working to eliminate their catch of turtles, and to establish a national Loggerhead refuge. Bravo.”


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