Tuesdays with Turtles – Triumphant Return

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.

I confess to knowing very little about the flatback. It’s only found around Australia and is listed as threatened. This news item caught my attention (for obvious reasons)

Turtles may fall victim to Australian gas project – International Herald Tribune

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.

A little old, but turns out that the WWF is establishing a hatchery for Olive Ridley sea turtles in Orissa.

WWF-India comes with artificial hatchery for Olive Ridley eggs – Newindpress.com

Large-scale destruction of Olive Ridley eggs at nesting sites in the State’s coast has prompted WWF-India to come with an artificial hatchery. It would also double up as a hatching protection centre. The artificial hatchery has been established near mouth of Rushikulya river where WWF-India staff have stored a large number of Olive Ridley eggs along with the arrangements for safe hatching. Last month alone, 116 nests were safeguarded and around 13,000 Olive Ridley eggs were stored in the artificial hatchery. Till end of the week, more than 2,000 eggs have hatched, chairman of WWF-India, Orissa State Committee Saroj Kumar Patnaik said.

Hatcheries become necessary when the natural habitat can no longer be protected. The biggest advantage of a hatchery is the fact that once the eggs are relocated, they are now safe from poaching/predation. But, there are some disadvantages including the resources needed, the possible overcrowding effects if the hatcheries are not well designed, etc. Luckily, there are good resources available for building and managing a good hatchery. With the WWF’s funding and experience, I am sure it will be a very well managed hatchery.

My favorite turtle organization, the Chennai students’ sea turtle conservation network is in the process of getting a website together. It will be at http://www.sstcn.org, which is not much to look at right now!

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!

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.

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…