Forty Years of Monitoring Increasing Sea Turtle Abundance in the Gulf of Mexico

Abstract

Longitudinal data sets for population abundance are essential for studies of imperiled organisms with long life spans or migratory movements, such as marine turtles. Population status trends are crucial for conservation managers to assess recovery effectiveness. A direct assessment of population growth is the enumeration of nesting numbers and quantifying nest attempts (successful nests / unsuccessful attempts) and emergence success (number of hatchlings leaving the nest) because of the substantial annual variations due to nest placement, predation, and storm activity. We documented over 133,000 sea turtle crawls for 50.9 km (31.5 miles) of Florida Gulf of Mexico coastline from 1982–2021 for a large loggerhead turtle nesting aggregation and a recovering remnant population of green sea turtles. Nest counts and hatchling production for both species have significantly increased, but emergence success has not. Sea level rise and coastal developments undoubtedly influence habitats in the long-term, impacting nest site selection and potential recruitment from the loss of emerged hatchlings. However, the present indications for steady Gulf of Mexico recovery of loggerhead and green sea turtles and range expansions of Kemp’s ridley and leatherback turtles parallel findings of the Florida Atlantic coasts. This study indicates that effective conservation practices can be detected within time scales of 1–2 turtle generations.