Browsing by Author "Avens, L"

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    Hawksbill sea turtle life-stage durations, somatic growth patterns, and age at maturation
    (Endangered Species Research, 2021-01-01) Avens, L; Ramirez, MD; Goshe, LR; Clark, JM; Meylan, AB; Teas, W; Shaver, DJ; Godfrey, MH; Howell, L
    Sea turtles exhibit complex life histories, encompassing intermittent use of multiple spatially separated habitats throughout long lifespans. This broad scope presents challenges for collecting comprehensive biological and ecological data, yet absence of such information complicates evaluation of management strategies for populations at risk of extinction. Hawksbill sea turtles Eretmochelys imbricata are endangered worldwide, primarily due to long-term, directed harvest. However, available information regarding life stage durations, somatic growth patterns, and maturation attributes to enhance understanding of anthropogenic impacts and recovery potential remains constrained. To address these data gaps in the western North Atlantic, we conducted skeletochronological analysis for hawksbills stranded along US coastlines to generate straightline carapace length (SCL)-at-age and somatic growth data. Generalized additive mixed models and bootstrapped von Bertalanffy growth curves were used to characterize age at maturation and covariate influence on somatic growth. For a subset of turtles, annual bone growth incrementspecific stable isotope and trace element analyses were incorporated to evaluate habitat use relative to age. Integration of these data sources indicated that juveniles transitioned from oceanic to neritic habitat at 1-3 yr old and mean SCLs of 23-24 cm (range 15.7-35.0 cm). Initial ages at maturation for this population at minimum nesting female SCLs were estimated at 15-25 yr. Somatic growth varied significantly relative to size, age, and stranding location, while no association with sex or calendar year was observed. Our results demonstrate the utility of these complementary analytical approaches for generating baseline data fundamental to characterizing hawksbill sea turtle population attributes.
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    Informing research priorities for immature sea turtles through expert elicitation
    (Endangered Species Research, 2018-01-01) Wildermann, NE; Gredzens, C; Avens, L; BarriosGarrido, HA; Bell, I; Blumenthal, J; Bolten, AB; McNeill, JB; Casale, P; Di Domenico, M; Domit, C; Epperly, SP; Godfrey, MH; Godley, BJ; González-Carman, V; Hamann, M; Hart, KM; Ishihara, T; Mansfield, KL; Metz, TL; Miller, JD; Pilcher, NJ; Read, MA; Sasso, C; Seminoff, JA; Seney, EE; Williard, AS; Tomás, J; Vélez-Rubio, GM; Ware, M; Williams, JL; Wyneken, J; Fuentes, MMPB
    © The authors 2018. Although sea turtles have received substantial focus worldwide, research on the immature life stages is still relatively limited. The latter is of particular importance, given that a large proportion of sea turtle populations comprises immature individuals. We set out to identify knowledge gaps and identify the main barriers hindering research in this field. We analyzed the perceptions of sea turtle experts through an online survey which gathered their opinions on the current state of affairs on immature sea turtle research, including species and regions in need of further study, priority research questions, and barriers that have interfered with the advancement of research. Our gap analysis indicates that studies on immature leatherback Dermochelys coriacea and hawksbill Eretmochelys imbricata turtles are lacking, as are studies on all species based in the Indian, South Pacific, and South Atlantic Oceans. Experts also perceived that studies in population ecology, namely on survivorship and demography, and habitat use/behavior, are needed to advance the state of knowledge on immature sea turtles. Our survey findings indicate the need for more interdisciplinary research, collaborative efforts (e.g. data-sharing, joint field activities), and improved communication among researchers, funding bodies, stakeholders, and decision-makers.