Tuesdays with Turtles – Green Turtles Deluged?

Where I shamelessly defer to the experts, just listen to the podcast from the folks at seaturtle.org and their blog, twist (this week in sea turtles).
This Week in Sea Turtles

Meanwhile, in the great turtle race, my pick billie’s back in first, chased by the Stephen Colburtle…

Personal Note
I swear, this blog has gone to pot. Either I’ve been too busy at work (yes, that does not explain everything), or I have not been thinking enough. I started this blog so that when I saw something interesting, I would have to think a little bit, and gather some information to write about what I saw/read. Apparently, I don’t read/see any more (which is not true), I don’t think any more (possible), or I am too lazy to spend enough time thinking to throw a coherent blog post together.

This has got to stop, and it stops right now!!
End Personal Note
Back to the topic on hand…

The Pacific Leatherback is in serious trouble and is slated to go extinct soon.

ENN News Network

Experts at the Bellagio Sea Turtle Conservation Initiative have just concluded a conference to save the imperiled Pacific leatherback sea turtle from extinction. The International Union for the Conservation of Nature and Natural Resources (IUCN) has classified Pacific leatherbacks as critically endangered.

The meeting convened an internationally diverse group of scientists, conservationists, economists, fund-raisers and policy makers. One focus was the development of immediate actions to boost hatchling production of the Western Pacific nesting populations by protecting nests from predation, beach erosion and human consumption on the beaches of Indonesia, Papua New Guinea, Solomon Islands, Vanuatu, Vietnam and Malaysia. Although there are still hundreds of turtles nesting, with 75 percent in one area on the north coast of Papua (Indonesia), researchers are concerned by new information indicating that the majority of nests laid are not producing hatchlings. Some simple procedures have been developed to improve hatch success, and applying these techniques now may ensure the populations are sustained in the future.

Some radical measures have been suggested, including cloning. Well, highly unlikely. Jurassic Park horrors and ethical dilemmas aside, cloning reptiles ain’t so easy.

What ails the Pacific Leatherback? Their numbers have dropped from 115000 reproductive females to less than 3000. This news release from a 2004 conference has more. But the usual suspects are destruction of nesting habitats, long line fishing, egg poaching, and to a more uncertain degree, climate change.

It’s depressing, I’ve never seen a leatherback, I guess I need to get on the case and see one before they disappear for ever.

Since this is the Olive Ridley blog (hint, it is a sea turtle), I do write occasionally about sea turtles. this is a random bit of sea turtle news out of Texas, and it is a feel good story…

Sea Turtles Rescued From Chilly Waters – New York Times

At least three dozen juvenile sea turtles have been rescued from an arctic blast that caused the water temperature in an arm of the Gulf of Mexico to fall 18 degrees in 48 hours. The turtles, which are cold-blooded, were left comatose by the rapid temperature drop this week in the shallow bay where they feed. Animal rescuers feared that the cold would kill the turtles or make them so sluggish that they would be vulnerable to sharks.

The nice thing about sea turtle conservation is that they are good looking beasts, harmless and very accessible. Anyone who summers on the coast of North Carolina, for instance, can see at least a cordoned off area marked as a sea turtle nests. And they’re encouraged to keep watch for hatching, keep any eye on the nest, watch out for nesting turtles, etc. U.S sea turtle conservation has a long, and fairly successful history.

Here’s more on the green turtle.

Photo’s courtesy of NOAA’s fisheries website.

An interesting paper featuring a North Carolinian turtle researcher Larry Crowder from Duke University:

Blackwell Synergy – Conservation Biology, Volume 21 Issue 1 Page 79 – February 2007 (Full Text)

Abstract: Although some sea turtle populations are showing encouraging signs of recovery, others continue to decline. Reversing population declines requires an understanding of the primary factor(s) that underlie this persistent demographic trend. The list of putative factors includes direct turtle and egg harvest, egg predation, loss or degradation of nesting beach habitat, fisheries bycatch, pollution, and large-scale changes in oceanographic conditions and nutrient availability. Recently, fisheries bycatch, in particular bycatch from longline fisheries, has received increased attention and has been proposed as a primary source of turtle mortality. We reviewed the existing data on the relative impact of longline bycatch on sea turtle populations. Although bycatch rates from individual longline vessels are extremely low, the amount of gear deployed by longline vessels suggests that cumulative bycatch of turtles from older age classes is substantial. Current estimates suggest that even if pelagic longlines are not the largest single source of fisheries-related mortality, longline bycatch is high enough to warrant management actions in all fleets that encounter sea turtles. Nevertheless, preliminary data also suggest that bycatch from gillnets and trawl fisheries is equally high or higher than longline bycatch with far higher mortality rates. Until gillnet and trawl fisheries are subject to the same level of scrutiny given to pelagic longlines, our understanding of the overall impact of fisheries bycatch on vulnerable sea turtle populations will be incomplete

Adult sea turtle killing by humans occurs due to

1. Harvest, killing them deliberately for food
2. Incidental bycatch in fishing nets
3. Habitat loss

The paper focuses on long line fishing and its effects on turtle mortality. So, if like me, you’re not a fisherperson, what is long line fishing and what are some other kinds of fishing techniques that have effects of sea turtles? Well, the Duke Project GloBal research team on studying bycatch has a nice primer. Some highlights:

1. Longlines: As the word suggests, longlines are very long (>10 km) lines of 2000+ individually baited hooks that drift close to the surface and are used to catch tuna, swordfish, halibut, etc. Crowder’s paper suggests that while each individual longline hook has low probability of catching a turtle, because of their number and ubiquitousness, they catch many many turtles.
2. Gillnets: These are giant rectangular mesh nets, either stationary or drifting, that catch marine life indiscriminately. There’s not much that can be done by way of reducingsea turtle catch in gillnets, except monitoring, observation and just using less of them
3. Trawls: Big funnel shaped bags that catch fish. Bottom trawling fishing boats used to, and still catch turtles at an alarming rate. Trawls are now (at least in the U.S and other “developed” countries) required to be outfitted with Turtle Excluder Devices (TEDS) to let turtles swim to safety.
4. Purse Seines: These are weighted on the bottom and float at the corners. They are indiscriminate, and especially hard on dolphins. It appears that mitigation efforts aimed at reducing dolphin mortality have the unintended effect of increasing sea turtle catch. Battle of the cute species!!

Take home message? Catching fish causes a lot of turtles to die. While trawl fishing is the worst culprit, it is also the most studied and the technique for which a viable mitigation strategy exists. THe other kinds of fishing are less studied, and there is precious little that can be done to avoid sea turtle bycatch.

Happy fishing!

This is almost a 1000 juveniles killed in a year in Baja California alone. The authors mention that over 99% of all fisherpeople are employed in small scale fisheries, which surprised me.

PLoS ONE: Small-Scale Fisheries Bycatch Jeopardizes Endangered Pacific Loggerhead Turtles:

Although bycatch of industrial-scale fisheries can cause declines in migratory megafauna including seabirds, marine mammals, and sea turtles, the impacts of small-scale fisheries have been largely overlooked. Small-scale fisheries occur in coastal waters worldwide, employing over 99% of the world’s 51 million fishers. New telemetry data reveal that migratory megafauna frequent coastal habitats well within the range of small-scale fisheries, potentially producing high bycatch. These fisheries occur primarily in developing nations, and their documentation and management are limited or non-existent, precluding evaluation of their impacts on non-target megafauna.

This is a surprising and unexpected finding because you would expect smaller fishing boats to have smaller impacts. I guess smaller scale fishing fleets in Mexico (and other developing nations) have not been targeted for education, awareness and enforcement of turtle safe fishing practices.

The good news from the study is that a major source of mortality has been identified and the authors point to recent efforts to increase awareness in the community about turtle safe fishing. But it will be a long and hard fight to be tackled all over the world.