Abstract

Population size estimates are one of the key parameters used in population assessments to evaluate and determine species’ conservation status. Typically, sea turtle population estimates are made primarily from nesting beach surveys, which capture only hatchling and adult female life stages and can display trends opposite of the full population. In-water studies are critical to improve our understanding of population dynamics of declining and recovering species as they can target the full range of in-water life stages. This study aims to expand sea turtle population studies within the northeastern Gulf of Mexico (neGOM) by collecting data on sea turtles in-situ using a stereo-video camera system (SVCS). Dive surveys were performed weekly with the SVCS which permits 3D measurements to be extracted from video footage. Straight carapace length (SCL) was measured digitally, and photo-identification was used to document all individuals. Our in-water study observed three species of sea turtle (Chelonia mydas, Caretta caretta, and Lepidochelys kempii) and all neritic life stages (juvenile, sub-adult, and adult) inhabiting artificial habitats. Thirty-three sea turtles were recorded and measured using the SVCS. Chelonia mydas, green sea turtles, size ranged from 28.55 – 66.96 cm (mean 43.07 cm ± 11.26 cm standard deviation; SD) and Caretta caretta, loggerhead sea turtles (n = 19) ranged from 59.71 – 91.77 cm (mean 74.50 cm ± 11.35 cm SD). Size distribution was impacted by habitat type and species of sea turtles. Our results indicated that artificial reefs may be an important developmental habitat for juvenile green turtles. Filming per unit effort was on average 1.17 turtles/hr. Overall, our novel methodology contributes to an enhanced understanding of the popula-tion structure of sea turtle species within the neGOM.

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