Thursday, July 17, 2008

Scientific Study Provides New Hope for Leatherback Turtle

It's a sciencey week here on this blog. A few days ago I discovered another very interesting scientific paper that I just had to report on. This paper, as with the last one I reviewed, was also published in the Public Library of Science (PLoS) Biology Journal.

This particular article deals with Leatherback Sea Turtles. For long time readers you will remember a post here back in May of 2006 titled Saving the Leatherback Turtle. This post was a summary of Karyn and I's experience on an Earthwatch Institute trip to work with endangered Leatherback Sea Turtles in St Croix. This was a fabulous experience which I still cherish to this day. The result is that I do know a bit about Leatherback Turtles and have taken a closer interest ever since. We even helped attach GPS tracking harnesses to a few of the female turtles in conjunction with NOAA. I still remember laying in the sand near the surf reaching under this 800 pound monster to help attach the harness. This experience was a major factor in my eventual decision to return to school. I assume the harnesses that we attached to be very similar to those used in the study.

Lets get on to the article:

Persistent Leatherback Turtle Migrations Present Opportunities for Conservation Shillinger GL, Palacios DM, Bailey H, Bograd SJ, Swithenbank AM, et al. PLoS Biology Vol. 6, No. 7, e171 doi:10.1371/journal.pbio.0060171

The paper describes a large multi-year study of the migration routes of female Leatherback Turtles after they leave the nesting area. The hope of the study was to find if common patterns could be identified that could be used in targeted conservation programs. The result is that they did identify two specific areas in the Pacific Ocean that if protected for part of the year could have a large impact on reducing bycatch and death of Leatherback Turtles.

It's important to note that the Leatherback Sea Turtle is listed as critically endangered by the IUCN. This is the highest classification of endangered species before "Extinct in the Wild". The Eastern Pacific Ocean population studied in the paper has decreased by greater than 90% in the last two decades. This has happened with strong conservation programs in place on the nesting beaches. The problem is in the oceans.

The study attached GPS tracking units that report locations back through satellites to an impressive 46 different female turtles in three different nesting years (27 units in 2004, 8 in 2005, and 11 in 2007). The result is that within a given year the vast majority of females leaving the nesting area followed roughly the same path to the feeding grounds even though they did not all travel together. When compensating for variable currents, the paths became even more consistent and were more consistent from year to year.

This consistent path concentrates individuals in a few key areas at similar times. By protecting these areas during those time windows conservation could be greatly enhanced.

It is noted in the study that this population of turtles may be unique in its focused path to its feeding grounds. Some of the other world populations tend to rely more on the currents. The potential hypothesis for this were quite interesting. One was that this population might have a more organized feeding ground. That the demands of egg production might cause a more urgent need to get to those feeding grounds. A much more depressing hypothesis is that through our fishing practices we might have already extirpated the phenotypes which would travel elsewhere.

I found this a very compelling and impactful article personally, possibly due to my emotional attachments to Leatherback Turtles. The experience of acting as a Leatherback mid-wife can have that effect. Regardless, the data demonstrates specific, fairly low cost conservation efforts which could have a significant impact on the reduction of Turtle bycatch and thus provide hope for their survival. Tactically it has also broadened my perspective on approaches of conservation sciences.

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2 comments:

Diego Vargas said...

Playa Grande neighbors go to court for damage to leatherback turtles

On July 1, an appeal for protection was filed before the Constitutional Court by the Playa Grande Neighbors Association, arguing serious damage is being caused to the leatherback turtles that come to nest on the Guanacaste beaches of Playa Grande and Playa Ventanas.

Julio Saenz, a member of the community group, said he was going “to present proof that scientific research led by the organization The Leatherback Trust (President Jim Spotila), has made it so that these endangered turtles are not coming back to nest on these beaches, which are part of the Las Baulas Marine National Park.”

The experiment being questioned was conducted for scientific reasons. However, the Playa Grande Neighbors Association has indicated that none of the turtles fitted with the radio transmitters returned to their nesting site. That’s the main reason for the appeal for protection (recurso de amparo) that they filed with the Constitutional Court, and which is now being reviewed by its magistrates.
Of the 27 turtles that were outfitted with the devices in the 2003-2004 season, none returned to their nesting site, despite the fact that leatherbacks return to their nests, on average, 3.7 years after the time they migrated.

This information was presented in the reports issued by researchers with The Leatherback Trust, and which the Playa Grande neighbors have copies of. Meanwhile, 40 other turtles that were not given a transmitter, also on the 2003-2004 season, did return to their nests the following season.

In this sense, the appeal for protection accuses The Leatherback Trust of violating a series of international agreements ratified by Costa Rica for the protection of flora and fauna, according to article 7 of the country’s Constitution. The complainants are asking the Constitutional Court to ban experiments done with the turtles, as they could generate “an irreversible effect against the environment, according to the appeal presented against SINAC, the Tempisque Conservation Area, and the Ministry of the Environment and Energy (MINAE).

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wolf21m said...

Diego, That is very interesting news. Do you know of an english language news source that I can keep up to date on this issue?

This is a very difficult situation. Any monitoring of any endangered species has the possibility of interfering negatively. Having worked to attach two of these transmitter harnesses to Leatherback Turtles myself (on St Croix), I can tell you that they are indeed intrusive. I am not sure if I believe that they caused the turtles to not return, but it is definitely a possibility. Intrusive science is always a difficult ethical dilemma.

Thanks for taking the time to post a comment on this important topic.