Trends in Reproductive Indicators of Green and Hawksbill Sea Turtles over a 30-Year Monitoring Period in the Southern Gulf of Mexico and Their Conservation Implications

Long-term monitoring programs of species at risk are efficacious tools to assess population changes, evaluate conservation strategies, and improve management practices to ensure populations reach levels at which they can fulfill their ecological roles. For sea turtles, annual nesting beach surveys are the most accessible method to estimating the population abundance and reproductive output, especially when these are done in primary nesting sites. However, little data exist on the long-term assessment of these parameters. Here, we present the trends of the nest abundance, female size, hatching, and emergence success of hawksbill (Eretmochelys imbricata) and green (Chelonia mydas) turtles at key nesting beaches in the southern Gulf of Mexico over 31 years (from 1990 to 2021). The nest abundance showed an increasing trend in both species as a result of the sustained protection and conservation effort, but there was no significant temporal trend in the annual female size, clutch size, hatching, and emergence success. However, these indicators showed decreasing mean values over the last decade and should be closely monitored. We suggest these decreases link to the combined effects of ocean warming and anthropogenic pressures affecting the sea turtle foraging grounds. Aside from protecting key nesting sites, protecting and restoring crucial foraging habitats should be an immediate priority requiring international cooperation.

Leave No Trace ordinances for coastal species management: influences on sea turtle nesting success

Coastal environments provide critical ecosystem services but experience a number of threats including marine debris and abandoned beach equipment. To address this threat, municipalities have begun enacting policy measures such as Leave No Trace ordinances. The impact of these ordinances on coastal species management has not yet been established. To evaluate the effectiveness of Leave No Trace ordinances in coastal species management, sea turtle crawl distribution, nesting success, and the frequency of obstructed crawls pre- and post-ordinance at a loggerhead sea turtleCaretta carettanesting beach in Alabama, USA, were compared between 3 treatment groups: (1) Gulf Shores and Orange Beach with new Leave No Trace ordinances enacted in 2016, (2) Fort Morgan with no ordinance, and (3) the Bon Secour National Wildlife Refuge (NWR) and Gulf State Park with Leave No Trace ordinances but no resident human population. The ordinance had no significant effect on crawl distribution or nesting success across the study site post-ordinance. However, the frequency of obstructed crawls in populated areas declined by 18.1% with the ordinance. The presence of a resident population was a more significant driver of obstructed crawls than the ordinance, as the Bon Secour NWR and Gulf State Park had fewer obstructed crawls than either populated treatment. With time and increased compliance, Leave No Trace ordinances may have the potential to improve coastal species management and increase coastal ecosystem services through reduced marine debris entanglement and ingestion, reduced physical damage to the environment, and increased tourism revenue and environmental education.