Marine turtles and IUCN Red Listing: A review of the process, the pitfalls, and novel assessment approaches

Marine turtles have been exploited by humans since pre-history, with particular intensity in the last century, the result of which has been the depletion of most nesting populations in the world. In many cases these declines have been reversed thanks to a variety of effective conservation programs. Several nesting populations maintain positive growth trends, although most are probably depleted relative to historic levels, while others continue in a severely depleted state, with little or no population growth in recent decades. This mosaic of population trajectories along with demographic and life-history traits that buffer against extinction has created unique challenges for marine turtle assessments such as those by the World Conservation Union's (IUCN) Marine Turtle Specialist Group, which conducts global assessments for the IUCN Red List. While the Red Listing approach describes extinction risk, which theoretically can be useful for developing conservation priorities, the descriptors that have been assigned to marine turtles so far (e.g. Vulnerable, Endangered, Critically Endangered) state an unrealistic imminence of extinction, a problem enhanced by the fact that its global resolution fails to reflect the disparate population trends ongoing in different regions worldwide. Coupled with misuse of the Red List by governments and conservation organizations worldwide, these shortcomings have led to increased debate regarding its efficacy for marine turtles. In this paper we describe the Red Listing assessment process, the problems associated with this approach for marine turtles, as well as the overall value of Red List assessments for marine turtle conservation. We suggest that Red list assessments for marine turtles at the global scale do not accurately depict the current status of marine turtles and may have unintended consequences for their conservation. Largely the data do not exist, or are not reliable, making the use of the current criteria intractable. We discuss novel methods for conducting marine turtle assessments, such as using a wider array of the current Red List Criteria, modelling future population dynamics, and developing regional assessments and/or conservation prescriptive assessments.