Now we know where Juvenile sea turtles Hide

Byoliveridley

You see the hatchlings as they dig out of the nests all small and helpless and make a beeline towards the sea. You see the adult female as she comes back to lay her eggs. You see adult males when you go snorkeling , but the juveniles had kept a low profile, until now…

Sea turtles’ mystery hideout revealed – LiveScience – MSNBC.com

Once sea-turtle hatchlings hit the surf, they vanish for up to five years. Where the half-dollar-size tots spend these ‘lost years’ while ballooning to the size of dinner plates has been a mystery, until now.

New research, published in the online edition of the journal Biology Letters, indicates the green sea turtles (Chelonia mydas) hide out in the open ocean, where they feast on jellyfish and other marine creatures.

Turns out that they’ve been “hiding out” in the open ocean eating meat to augment their vegetarian adult diet. I have not seen the paper (reference below), but the study was based on an analysis of their shell content. Carbon and Nitrogen isotope analysis was used as a marker for diet and location.

The ‘lost years’ of green turtles: using stable isotopes to study cryptic lifestages

Kimberly J. Reich, Karen A. Bjorndal, Alan B. Bolten

Archie Carr Center for Sea Turtle Research, Department of Zoology, PO Box 118525, University of Florida, Gainesville, FL 32611, USA

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    Killer nets reinstated

    Byoliveridley

    Council Decisions: March 2006

    Drift Gillnet Management

    The Council adopted a recommendation to NMFS to authorize an exempted fishing permit (EFP) that would allow drift gillnet fishing in the current August 15-November 15 closed area. The EFP fishery would be governed by several requirements for all vessels, including, to carry an observer; to limit total fishing effort in the EFP fishery to 300 sets; to immediately cease the EFP fishery if, and when, two leatherback sea turtles were encountered by the fishing gear; and to immediately cease the EFP fishery if one mortality or serious injury occurred to any of the following marine mammals: short-finned pilot whale, sperm whale, fin whale, gray whale, humpback whale, or minke whale.

    And, with that, starts the rather egregious practice of drift gillnet fishing. The restrictions seem fairly tight, an observer on every boat, and end to the fishery after two incidences of capture. There is definitely more than meets the eye here, I don’t know what. Drift gillnet fishing is well documented to cause turtle catch, this from the 1998 Fishery Bulletin for 1990-1995

    In the drift gillnet fishery, seven out of 387 mammals observed entangled were released alive. In the set gillnet fishery, five out of 1,263 mammals observed entangled were released alive. Estimates of incidental kill are presented along with estimates of entanglement for species that were observed to be released alive. For the period under consideration, the estimated mortality for the drift gillnet fishery was over 450 marine mammals each year. A total of 20 turtles and 3 seabirds were observed entangled during the entire period. The most frequently entangled species in this fishery were common dolphins, Delphinus spp., and northern elephant seals, Mirounga angustirostris. Estimated cetacean mortality in the driftnet fishery decreased from 650 in 1991 to 417 in 1995; pinniped mortality decreased from 173 in 1991 to 116 in 1995. Estimated cetacean mortality in the set gillnet fishery ranged from a high of 38 in 1991 to a low 14 in 1993; pinniped mortality rose to a high of 4,777 in 1992 and then decreased to 1,016 in 1995. We postulate that there has been a decline in the number of pinnipeds and cetaceans in the setnet fishery owing to area closure. No similar proposal can be made for the driftnet fishery. The most frequently entangled mammals in the setnet fishery were California sea lions, Zalophus californianus, and harbor seals, Phoca vitulina. Six turtles and 1,018 seabirds were estimated entangled in this fishery during the NMFS Observer Program from July 1990 to December 1995.

    So what’s the deal, this thing caught 20 turtles in 5 years, so it is going to catch turtles, no doubt about it. Anyone who does not get what the death of one adult sea turtle means read this. Sea turtles are wonderfully fragile animals given their size, they take long to mature sexually, they do not breed all that much and less than 1% of turtle hatchlings survive to adulthood. Leatherbacks are highly endangered.

    I have a feeling that this is the first part of a one-two punch intended to reinstate the famed turtle killer long line swordfish nets on the pacific coast. The “proof” that these nets do not catch turtles will be used to lobby for longline swordfishing in, oh say three months?

  • Tuesdays with Turtles – Outback Edition

    Byoliveridley

    flatback-kp.jpgWell, 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.

  • Sea Turtle News of the day, genocide edition

    Byoliveridley

    Depressing as always, but this is a yearly headline around turtle nesting season.

    1,000 Giant Turtles Wash Ashore in India, Bangladesh

    It’s nesting season for the sea turtles of Bangladesh and India, but this year the beaches where the animals lay their eggs are eerily still.

    Nearly a thousand dead turtles have washed ashore along the coasts of both countries in the past few weeks, conservation workers report.

    About 200 dead reptiles have appeared in the past week alone along a single stretch of beach, pictured here, in the Bangladeshi tourist town of Cox’s Bazar (see Bangladesh map).

    A team of scientists visiting the beach on Monday to investigate the mysterious mass deaths concluded that fishing nets were to blame.

    Sea turtles swarming the shores to nest are getting entangled in poorly laid nets and drowning, the experts told Bangladesh’s Financial Express.

    The survival rate of turtle hatchlings is estimated at anywhere between 0.1 and 1%. Assuming 0.5%, this represents 20000 hatchlings. Assuming a hatching success (not all eggs hatch successfully) of about 2/3rds, that is 30,000 eggs, or between 200-250 nests. In my two years of turtle conservation work on an approximately 3 mile stretch of beach, we relocated about a 100 nests. These aren’t the same turtles (they tend to come back to nest very close to where they hatched), but there’s my two seasons of work down the drain and then some!

    Turtle safe fishing is a well researched technology and is not expensive. As I have mentioned before in a similar context, the gaps between the availability of a certain technology and its actual adoption and use are depressingly huge.

    When it comes to serious problems like global warming, all the talk is going to be about the cool science and innovative solutions, but how the technology transfers to India and China, how it is implemented, and the nature of the interactions between the traditional powers and the emerging ones is going to be more critical than the science. Something to remember as a scientist!

  • Tuesdays with Turtles – Hatcheries

    Byoliveridley

    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.

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    Tuesdays with Turtles – Travel Edition

    Byoliveridley

    sm_mapping.jpgIt’s travel all the time for sea turtles. Of course, the great turtle race is finally on, and windy’s in the lead, my pick billie’s in second place, a mere 30 miles behind. There’s a new turtle in the race, Colbertia, named in honor of Stephen Colbert, in third place.

    Anything that gets turtles some attention is good.

    But this is only a 500 mile sprint. PBS’ nature series had a one hour documentary on an 8000 mile, one plus year journey of a loggerhead turtle from her juvenile feeding grounds in Mexico to her adult breeding ground in Japan. It’s great to spend an hour at that close proximity to a turtle. But to me, the other animals, the dolphin pods, the giant fish swarms, the hammerhead sharks, the other sharks, the jelly fish, those little fish that eat parasites off the turtles and sharks kinda stole the show. There is something about thousands of animals of the same species doing something in concert. 

    Anyway, nothing more to say, except that 8000 miles is a long way at a mile an hour. I don’t think any of us can appreciate the mindfulness and sense of purpose (do turtles have these qualities, or do they just keep on chuggin’?), not to mention the huge amount of luck it takes to get it done.

  • Tuesdays with Turtles – Lighsticks Kill

    Byoliveridley

    Following up on the fishing issues from last week, here’s word that lights used to lure tuna towards longline fisheries attract juvenile sea turtles as well.

    Article – Science & Technology – Lightsticks may hold deadly attraction for sea turtles

    RALEIGH, N.C. Longline fishermen use lightsticks similar to the glowing tubes that delight trick-or-treaters to lure tuna and swordfish to baited hooks. New research by University of North Carolina-Chapel Hill scientists suggests that for endangered sea turtles the lights may hold a fatal attraction.

    Lab experiments by Ken Lohmann, a University of North Carolina biology professor and John Wang, a graduate who is now a research associate at the University of Hawaii and National Marine Fisheries, found that young loggerhead turtles in a tank tended to swim toward lights.

    It’s well known that hatchling turtles on a beach will crawl toward lights as they try to find the surf. But researchers did not know whether juvenile loggerheads in the water shared that attraction. Young loggerhead and leatherback sea turtles, which are protected because of declining numbers, are inadvertently hooked during longline fishing.

    Well, not so surprising, is it? Bioluminescence is a common enough phenomenon that especially at night, animals will be attracted to light as it can signal food. It’s tricky, but when you try to catch fish, tyou will catch other animals as well. So, when you change something about the way you catch fish, you need to study how it affects other endangered species…

    Off topic, but it is ironic that I read this in the ocregister, which is a newspaper from Orange County, California. It reported on work done by UNC Chapel Hill, which is in Orange County, North Carolina.