Effective conservation often comes down to a matter of scale and strategy. For threatened species that range across the globe, often the biggest challenge to conservation is knowing how to prioritize limited resources to the areas that need them most. In an article published today in the journal Public Library of Science ONE, the world’s leading marine turtle experts have developed a new framework to address this challenge for highly migratory—and highly threatened—marine turtles.
The study’s authors, all part of the IUCN’s SSC Marine Turtle Specialist Group (MTSG), compiled decades of research from thousands of sources over a two-year process to create a novel system for defining biologically independent population segments of marine turtle species, which they termed Regional Management Units (or RMUs). These RMUs represent functionally unique populations of the same species toward which management and research efforts can be directed.
How does the RMU concept work? Think of marine turtle populations like Russian dolls; there are several parts that fit biologically and spatially within each other, and although each can be defined separately, the truly complete form has all pieces fit one within the next. Female turtles return to the same nesting sites throughout their entire lives, forming nesting populations that can be defined genetically. These nesting populations are then connected by male turtles, which can mate with females from several populations, forming a broader breeding population. Males, females, adults, and juveniles from multiple breeding populations can then congregate in common feeding and migratory areas, creating another layer that links the populations. RMUs encapsulate all of these layers to define discrete, coherent segments, or regional populations, for each species. This system gives scientists and conservation managers a micro-to-macro view into population status, risk and threats.
The authors defined 58 RMUs worldwide across the seven marine turtle species, ranging from 17 RMUs for the globally distributed Green Turtle (Chelonia mydas, Endangered) to a single RMU for the diminutive Kemp’s Ridley Turtle (Lepidochelys kempii, Critically Endangered), which spends nearly its entire life cycle within the Gulf of Mexico.
The MTSG teamed up with Duke University’s OBIS-SEAMAP project to make all of the information used to develop the RMUs (which includes more than 1,200 references, nearly 3,000 nesting sites, and over 100 genetic stocks) publicly available via interactive, web-based maps at http://seamap.env.duke.edu/swot. This will allow the public, researchers, and conservation managers to view, interact with, and use the data for conservation and research initiatives.
The authors envision the RMU concept being applied to other widespread marine species with similar natural histories, like sharks, seabirds, and marine mammals.
At least for now, the global view of marine turtles just came into better focus. And that’s a major development for the conservation of some of the ocean’s key flagship species.