Originally posted by Bryan Wallace on Conservation International’s Blog
September 28, 2011
CI’s Sea Turtle September continues this week with the publication of a new paper in the scientific journal PLoS ONE on global priorities for sea turtle conservation. Lead author Bryan Wallace blogs about the challenges of this work.
Assessing the status of almost any species is a tough task. Most are difficult to count because they move a lot, are hard to find or their distributions are unknown, and very few have been monitored for long enough to know whether their abundance is increasing, decreasing, or remaining stable.
Marine species that live a long time, have complicated life cycles and are highly migratory make the job even harder. Species like seals, sea lions and seabirds can have enormously broad distributions spanning international boundaries, but also tend to aggregate in relatively discrete habitats during certain times of the year. These factors expose different populations to different environments and threats, which manifest in differences among populations of the same species.
So with all this in mind, how should we prioritize our limited conservation resources?
Sea turtles present a prime example of these challenges. Experts in sea turtle biology have long recognized differences among populations of the same species, which can be due to localized threats, environmental conditions or conservation efforts. And for decades, there was no agreement on how to assess the conservation status of these populations.
A new paper published in the scientific journal PLoS ONE has just made setting conservation priorities for sea turtles a little easier. Over the past few years, I’ve worked with a team of global experts in sea turtle biology and conservation from the IUCN/SSC Marine Turtle Specialist Group to come up with a way to assess and compare the current status of every sea turtle population on the planet.
Our expert working group developed a ranking system that scored the status and threats to all populations globally. This process identified the most endangered populations in the world, but also provides various ways to look at sea turtle status, such as examining all populations of a given species or all populations in a given region, highlighting threats with the biggest impacts, and so on.
One particularly useful application of this framework is identifying the key components of healthy populations. While focusing resources and attention on the most endangered populations is necessary to avoid local extinctions, understanding the traits of large, growing populations provide insights for successful actions in sea turtle conservation.
For example, in the East Pacific Ocean, where I have spent most of my career studying sea turtles, three populations — leatherbacks, hawksbills and loggerheads — made the list of the world’s most endangered sea turtles, while two others — greens and olive ridleys — are among the world’s healthiest. While this result seems perplexing at first, a closer examination reveals some important take-home messages.
For decades, green turtles and olive ridleys were subject to intense harvest for their meat, eggs and other products — especially in Mexico, home to major nesting assemblages of both species. However, following a 1990 ban on consumption of sea turtle products in that country, which — and this is the key — has been enforced, these populations have recovered significantly. So, for these species at least, conservation intervention happened at the right time, in the right place, and has remained consistent.
At the same time, I’ve witnessed the shocking decline of leatherbacks while patrolling nesting beaches in Costa Rica and in Mexico, and although conservation programs have worked for many years to remove threats on beaches, threats from fisheries bycatch persist. Likewise, hawksbill turtles in the region continue to be under high threats from egg consumption and harvest for their valuable shell material.
Our study has created a blueprint to prioritize sea turtle conservation efforts for the populations most in need of help. Now it’s time to get to work.
Bryan Wallace is director of science and strategy for CI’s Marine Flagship Species Program, and co-regional vice-chair (East Pacific Ocean region) for the IUCN/SSC Marine Turtle Specialist Group. Download the paper (PDF–700.50 KB).
PHOTO CAPTION: Green turtle (Chelonia mydas).
PHOTO CREDIT © Pierre Lesage