Population dynamics of the endangered Kemp’s ridley sea turtle following the 2010 oil spill in the Gulf of Mexico: Simulation of potential cause-effect relationships

Abstract

The Kemp’s ridley (Lepidochelys kempii) is a critically endangered sea turtle that breeds nearly exclusively in the Gulf of Mexico, with scattered nesting along the U.S. Atlantic coast. In 2010, an unprecedented increase in strandings concomitant with a large oil spill in the northern Gulf raised concern about impacts on population recovery. We used several versions of an age-structured model representing hypothesized “pulse,” “press,” and “density-dependent remigration” effects of the 2010 mortality event to simulate post-2010 population dynamics. Only a “density-dependent remigration” version simulated population fluctuations observed from 2009 to 2014. Population dynamics projected through 2035 using this version indicated essentially exponential growth, with the simulated adult female population reaching ≈110,000 in 2035 (as indicated by nest counts at the index beach). Of most interest within a management context is the apparent resiliency of the population to large mortality events of short duration. Two important caveats to this statement are the assumptions that there has been no reduction of suitable habitats and that per capita availability of food resources is sufficient to support population recovery. Simulation results also provide insight into the myriad of potential responses of an age-structured population of long-lived animals to such events.