Category: sea turtles

Sea Turtle News o' the day – Global warming edition

ScienceDaily: Scientists Warn Of Climate Change Risk To Marine Turtles

North American marine turtles are at risk if global warming occurs at predicted levels, according to scientists from the University of Exeter. An increase in temperatures of just one degree Celsius could completely eliminate the birth of male turtles from some beaches. A rise of three degrees Celsius would lead to extreme levels of infant mortality and declines in nesting beaches across the USA.

Here’s the paper.

Like a lot of other reptiles, the sex of the hatchling is dependent on nest temperature. Warmer temperatures make female turtles (my mnemonic was hot females!), and even warmer temperatures just kill the eggs. But, I wonder if the turtles would adapt by nesting a little earlier. I don’t think it is yet clear when turtles decide to nest. If it is based on sea temperature, then they would eventually figure it out. This paper from 2004 appears to conclude that loggerheads in Florida do nest earlier than before, so there is hope.

John F. Weishampel, Dean A. Bagley, Llewellyn M. Ehrhart (2004) Earlier nesting by loggerhead sea turtles following sea surface warming Global Change Biology 10 (8), 1424–1427

The onset of spring, noted by the timing of wildlife migratory and breeding behaviors, has been occurring earlier over the past few decades. Here, we examine 15 years of loggerhead sea turtle, Caretta caretta, nesting patterns along a 40.5 km beach on Florida’s Atlantic coast. This small section of beach is considered to be the most important nesting area for this threatened species in the western hemisphere. From 1989 to 2003, the annual number of nests fluctuated between 13 000 and 25 000 without a conspicuous trend; however, based on a regression analysis, the median nesting date became earlier by roughly 10 days. The Julian day of median nesting was significantly correlated with near-shore, May sea surface temperatures that warmed an average of 0.8°C over this period. This marine example from warm temperate/subtropical waters represents another response of nature to recent climate trends.

So the truth lies somewhere between easy adaptation and giant swarms of frustrated female turtles!

Sea Turtle News of the day, genocide edition

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!

Obligatory Sea Turtle News o' the day

green turtle underwaterSince 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.

Fishing Major threat to Turtles

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.

BBC NEWS | Science/Nature | Fishing ‘major threat’ to turtles

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.”

Turtles, Arribadas, Science, Policy and Implementation

turtle Read stuff like this (hat tip to my mom for telling me about this report she’d seen on TV in Madras), and you begin to doubt your utility as a scientist.
IBNLive : Orissa turtles neck-deep in danger

Nearly 3,000 Olive Ridley turtles have died off the Orissa coast this season. Beaches have become turtle graveyards.

Orissa is one of the three places in the world where the Olive Ridleys come for their annual mass nesting.

Mechanised trawlers are the biggest culprits for this slaughter. When the trawlers go to the sea, turtles are trapped in their fishing nets. The turtles are unable to disentangle themselves and suffocate to death.

See the video report too. In her own breathlessly indignant style, the reporter explains the science behind turtle excluder devices (well known and established), the regulation expressely forbidding shrimp trawling close to the coast, especially during the arribada, the money set aside in the budget to purchase a few speed boats for the coast guard, who are well aware of the problem, so wot’s, uh, the deal?

The investigative reports contradict each other, the first one linked said there was no patrolling, the second one gushingly praises the coast guard for vigorous enforcement and patrolling, so which is it? I need to find out, call on some old friends… But clearly, there are issues if net catch mortality is on the rise.

The three pillars of any regulatory action are the science, the policy, and the implementation. The science here is very clear (though the US administration seems to not think so any more?), shrimp nets with turtle excluder devices cause decrease in mortality. The policy is clear, use these nets when shrimp fishing, and completely ban fishing activity during the arribada (the number of turtles in an arribada, 50000 in a night and perhaps 300000-400000 over the course of a week is staggeringly large, so, shrimp net or not, you’ll kill a lot of turtles just by being there).

So, like anything else in India, where is the implementation? The people running the trawlers know they are illegal anyway, so they don’t bother with the TEDs. The owners of the trawling boats never face the consequences, only the poor hapless fishermen running the boats. No attempt is made to coopt the people being regulated, it is a top down “we tell you what to do” kind of situation where the law is selectively enforced, no explanations are given, the regulation may just be an excuse to get some kickbacks. The fishermen see the excluder device as an inconvenience as they are not shown how to use it. Some low level bureaucrat in charge of buying high speed boats for the state’s forest service either does not realize the importance of getting this policy on the road, or is on the take. You can pick any, or all of these reasons and you’ll see why just like most other things in India, the road to hell is paved with good intentions 🙁

Why be a scientist and come up with cool new techniques to do things when you don’t pay equal attention to the implementation of techniques invented 20 years back? As a responsible scientist, I must look at policy and implentation with as much interest and passion as I look at the science – New career paths?

Killer nets reinstated

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?