Abstract

Kemp’s ridley sea turtles (Lepidochelys kempii) are the most critically endangered species of sea turtle and are prone to incidental capture by recreational fishermen in Mississippi.^1–2 These anthropogenic interactions lead to the need for medical intervention of these turtles, where the hooks are often removed. In this study, the type of hook and location of each type of hook was evaluated for rehabilitated turtles from the Northern Gulf of Mexico in the state of Mississippi. Hook types and hook locations were also compared to patient outcome. The prevalence of hook types and locations were compared to a previous study of a similar population of Kemp’s ridley sea turtles (Heaton 2016). Radiographs or endoscopy were used to determine hook locations. This information can be utilized to determine what types of hooks pose a stronger threat to sea turtle health based on prevalence and common locations where they get embedded.

From 2016 to 2020, 89 Kemp’s ridley sea turtles were admitted to a stranding network in Mississippi. A total of 72 hooks were removed or passed through the gastrointestinal tract from these turtles. Of these, 7 were Kahle hooks, 20 were circle hooks, 52 were J hooks, and 9 of the hooks were of unknown type. A total of 14 hooks were removed prior to intake, which accounts for the 9 unknown hook types. The locations that were evaluated for hook location were the oral cavity, tongue, cranial esophagus, mid-esophagus, caudal esophagus, unspecified esophagus, coelom, and externally. Of the 20 hooks found in the oral cavity, 45% were J hooks, 30% were circle hooks, 10% were Kahle hooks, and 15% were hooks of unknown type. Of the 17 hooks found in the cranial esophagus, 59% were J hooks, 29% were circle hooks, and 12% were Kahle hooks. Of the 30 hooks found in the mid-esophagus, 70% were J hooks, 23% were circle hooks, and 7% were Kahle hooks. Of the 8 hooks found in the caudal esophagus, 87.5% were J hooks and 12.5% were circle hooks. Of the 5 hooks that were found in an unspecified region of the esophagus, 60% were J hooks, 20% were circle hooks, and 20% were Kahle hooks. The one coelomic hook was identified as either circle or Kahle and was not removed prior to release. Of the 8 external hooks removed, 50% were J hooks, 37.5% were hooks of unknown type, and 12.5% were Kahle hooks. Nearly a third of all hooks were in the mid-esophagus over the 2016–2020 time frame, and J hooks predominated for hook type. Of the 89 turtles that presented for incidental hook capture, only 2 died while in hospital. One mortality was an individual that had a J hook in the esophagus, and the other was an individual that had a circle hook in the oral cavity. These mortalities could not be used to relate type of hook or hook location to case outcome. The remaining 87 turtles were successfully rehabilitated and released.

Acknowledgements

This research was supported by the Mississippi Marine Mammal and Sea Turtle Conservation Recovery and Monitoring Program, which is funded by the National Fish and Wildlife Foundation under Mississippi Department of Environmental Quality Agreement No. 18-00081. The authors wish to thank The Institute for Marine Mammal Studies (IMMS), IMMS’s veterinary and stranding team, and Dr. Moby Solangi. IMMS is a designated agent of the National Oceanic and Atmospheric Administration (NOAA). Rescue and rehabilitation activities were conducted under the Mississippi Department of Marine Resources and the US Fish and Wildlife Services permit #TE12392A-3.

Literature Cited

1.  Heaton AJ, Pulis EE, Pitchford JL, Hatchett WL, Carron AM, Solangi M. Prevalence and transience of ingested fishing hooks in Kemp’s ridley sea turtles. Chelonian Conserv Biol. 2016;15(2):257–264.

2.  Rudloe A, Rudloe J. Site specificity and the impact of recreational fishing activity on subadult endangered Kemp’s ridley sea turtles in estuarine foraging habitats in the northeastern Gulf of Mexico. Gulf Mex Sci. 2005;23(2):186–191.