Man, I have a serious case of the summer blahs and am in desperate need of a vacation. Anyways, can’t think very hard. Here’s a nice picture though, courtesy renoir7777’s photostream on flickr.
An interesting paper featuring a North Carolinian turtle researcher Larry Crowder from Duke University:
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
- Harvest, killing them deliberately for food
- Incidental bycatch in fishing nets
- 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:
- 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.
- 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
- 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.
- 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.
Well, not the least bit surprising, sea turtles have always been very difficult to track, and we’re finally getting verification that, gasp, turtles’ lives cannot be described in simple juvenile = open sea, adult = coast behavior.
Until now scientists have believed that young turtles live in the open ocean, but change to a coastal habitat when they reach a certain size.
But researchers working in Cape Verde found that most adults nesting there retain their open water behaviour, with the attendant risk posed by longline boats.
“The bottom line is that we thought juveniles experienced this risk out in the open ocean with longline fisheries,” said Brendan Godley from the University of Exeter.
“We thought that if you got them past that, then unless they’re being taken by inshore fisheries, you’re OK,” he told the BBC News website.
“But now you’ve got adults exposed to longline fisheries, which is very worrying.”
Well, since this blog gratuitously takes its name from a sea turtle, it’s only fair that there needs to be a turtle post at least once a week! Why Tuesday? Because it alliterates. Why not Thursday? Because apparently, Tuesday’s the day that you do things with other things, ask Morrie.
The peak nesting season is just drawing to a close for the flatbacks, a threatened species of sea turtle found only in Australia, when thousands of palm-sized hatchlings emerge from eggs buried under the sand and race to the sea. Every second counts: Between them and the ocean lies an army of hungry predators: lizards, dogs, foxes and gulls. Most of the turtles will never taste saltwater.
Development is another threat. Until now, the flatbacks could find some respite off the coast west of here, on Barrow Island, one of the country’s oldest nature reserves. But now environmentalists say that Barrow’s flatbacks may be among the victims of a plan by the oil giant Chevron to use Barrow Island for a roughly $8.6 billion project meant to supply natural gas to Japan and other energy-hungry nations.
“The environment is being made to pay for a poor business development model,” said Chris Tallentire, director of the Conservation Council of Western Australia in Perth.
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.
Now you know what to do when you hit Jekyll island, GA (no, don’t Hyde!)
It helps that they’re such handsome beasts.
I grew up in Chennai and worked with the Students’ Sea Turtle Conservation Network in the mid ’90s. It’s nice to see an article on them in the city’s biggest newspaper.
CHENNAI: Scores of newborn Olive Ridley turtles entered their natural habitat — the sea — under the watchful eyes of conservationists at Elliots Beach, Besant Nagar, here early on Sunday. Conservationists said nearly 75 eggs hatched on Sunday alone and most of the young ones were safely released into the waters. But about 25 eggs reportedly did not hatch and some were stillborn. Volunteers of the Students Sea Turtle Conservation Network (SSTCN) annually collect Olive Ridley turtle eggs from the Besant Nagar coastline upto Neelankarai, a fishing village beyond Tiruvanmiyur. The eggs are then taken to a hatchery at Oorurkuppam, a fishing village located behind the Theosophical Society premises. It takes 45 days for the young ones to hatch.
In Chennai, and most of South India, the adult sea turtles are not poached, only the eggs. Also, it is not possible to just secure the nest with “do not poach” notice! So the eggs need to be relocated to a hatchery where they’re re-buried. For more on sea turtle “management” in India, I would suggest visiting Kartik Shanker’s excellent website.