Confirmation of significant sea turtle nesting activity on a remote island chain in the Gulf of Mexico

Abstract

Globally, six of the seven sea turtle species are threatened or endangered and as such, monitoring reproductive activity for these species is necessary for effective population recovery. Remote beaches provide a challenge to conducting these surveys, which often results in data gaps that can hamper management planning. Throughout the summer of 2022, aerial surveys were conducted over the Chandeleur Islands in the Gulf of Mexico. Turtle crawls were photographed for subsequent review by 10 expert observers. Whenever possible, ground surveys were conducted, and samples of unhatched eggs or dead hatchlings were collected. A summary of historic reports of sea turtle nesting activity at this site was also compiled. On 11 days between May 4, 2022, and July 30, 2022, photographs of 55 potential sea turtle crawls were taken. Observers identified 54 of those as being made by a sea turtle. There was high-to-moderate certainty that 16 of those crawls were nests, that 14 were made by loggerheads, and that two were made by Kemp's ridleys. Observers were least certain of species identification when surveys were conducted during rainy weather. Genetic analyses based on mitochondrial and nuclear DNA were conducted on samples from five nests and those analyses confirmed that three nests were laid by Kemp's ridleys and two were laid by loggerheads. Historic records from the Chandeleur Islands substantiate claims that the Chandeleurs have supported sea turtle nesting activity for decades; however, the consistency of this activity remains unknown. Our aerial surveys, particularly when coupled with imaging, were a useful tool for documenting nesting activity on these remote islands. Future monitoring programs at this site could benefit from a standardized aerial survey program with a seaplane so trends in nesting activity could be determined particularly as the beach undergoes restoration.

Keywords: Gulf of Mexico; Kemp's ridley; aerial survey; sea level rise; sea turtle.

FIGURE 1

Chandeleur Islands lie off the eastern coast of Louisiana in the northern Gulf of Mexico (red box in inset). Several Kemp's ridley hatchlings (including the one photographed here by M. Weigel) were observed on the beach after emerging from a nest on the Chandeleur Islands on July 29, 2022. One dead hatchling was also found, and genetic analysis confirmed the species identification.

FIGURE 2

Examples of photographs taken from the aircraft of sea turtle crawls on the Chandeleur Islands, LA, in summer 2022. Images taken in clear sunny weather (a) resulted in more confident identifications by reviewers than those taken in rainy weather (b). The proportion of reviewers who agreed with each characterization along with the mean observer certainty rankings (in parentheses) are included on each image: was the crawl made by a sea turtle, what species of sea turtle made the crawl, and was it a nesting or non‐nesting crawl.