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Marine Ecology Progress Series

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MEPS 654:143-161 (2020)  -  DOI:

Regional differences in Kemp’s ridley sea turtle growth trajectories and expected age at maturation

Larisa Avens1,*, Matthew D. Ramirez2, April G. Hall1, Melissa L. Snover3, Heather L. Haas4, Matthew H. Godfrey5, Lisa R. Goshe1, Melissa Cook6, Selina S. Heppell2

1National Marine Fisheries Service, Southeast Fisheries Science Center, NOAA Beaufort Laboratory, 101 Pivers Island Road, Beaufort, NC 28516, USA
2Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR 97331, USA
3Lynker Technologies, PO Box 3673, Pago Pago, AS 96799, USA
4National Marine Fisheries Service, Northeast Fisheries Science Center, 166 Water Street, Woods Hole, MA 02543, USA
5North Carolina Wildlife Resources Commission, 1528 Ann Street, Beaufort, NC 28516, USA
6National Marine Fisheries Service, Southeast Fisheries Science Center, Pascagoula Laboratory, 3209 Frederic Street, Pascagoula, MS 39567, USA
*Corresponding author:

ABSTRACT: For species of conservation concern, somatic growth and age at maturation are key parameters in models used to evaluate population dynamics, as spatial and temporal variability in growth rates may be particularly important for predicting population recovery. Following an oceanic juvenile developmental stage, endangered Kemp’s ridley sea turtles Lepidochelys kempii occupy neritic habitats in 2 primary regions, the Gulf of Mexico (GoM) and along the US Atlantic coast. Results of prior studies suggest that somatic growth rates differ between these groups, which has the potential to influence maturation trajectories and relative reproductive contributions. To determine the nature and extent of potential regional differences, we conducted skeletal growth mark analysis (skeletochronology) with complementary annual bone growth increment-specific stable nitrogen isotope analysis that allowed delineation of oceanic-to-neritic habitat shifts for turtles stranded from 1993 to 2016. Results demonstrate that in the GoM, the oceanic-to-neritic habitat transition is associated with younger ages and faster somatic growth rates than in US Atlantic waters. Overall, US Atlantic somatic growth response was depressed relative to that in the GoM throughout all juvenile life stages, and this disparity persisted for more than 20 yr. This discrepancy translated into regional divergence in size-at-age relationships and maturation trajectories, with the prediction that US Atlantic Kemp’s ridleys would mature on average 2 to 3 yr later than their GoM counterparts. These analyses provide important baseline information on somatic growth rates and predicted age at maturation that can facilitate the evaluation of factors contributing to recent fluctuations in reproductive output for this endangered population.

KEY WORDS: Lepidochelys kempii · Age · Skeletochronology · Stable isotope analysis

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Cite this article as: Avens L, Ramirez MD, Hall AG, Snover ML and others (2020) Regional differences in Kemp’s ridley sea turtle growth trajectories and expected age at maturation. Mar Ecol Prog Ser 654:143-161.

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