Somatic growth dynamics are an integrated response to environmental conditions. Hawksbill sea turtles (Eretmochelys imbricata) are long‐lived, major consumers in coral reef habitats that move over broad geographic areas (hundreds to thousands of kilometers). We evaluated spatio‐temporal effects on hawksbill growth dynamics over a 33‐yr period and 24 study sites throughout the West Atlantic and explored relationships between growth dynamics and climate indices. We compiled the largest ever data set on somatic growth rates for hawksbills – 3541 growth increments from 1980 to 2013. Using generalized additive mixed model analyses, we evaluated 10 covariates, including spatial and temporal variation, that could affect growth rates. Growth rates throughout the region responded similarly over space and time. The lack of a spatial effect or spatio‐temporal interaction and the very strong temporal effect reveal that growth rates in West Atlantic hawksbills are likely driven by region‐wide forces. Between 1997 and 2013, mean growth rates declined significantly and steadily by 18%. Regional climate indices have significant relationships with annual growth rates with 0‐ or 1‐yr lags: positive with the Multivariate El Niño Southern Oscillation Index (correlation = 0.99) and negative with Caribbean sea surface temperature (correlation = −0.85). Declines in growth rates between 1997 and 2013 throughout the West Atlantic most likely resulted from warming waters through indirect negative effects on foraging resources of hawksbills. These climatic influences are complex. With increasing temperatures, trajectories of decline of coral cover and availability in reef habitats of major prey species of hawksbills are not parallel. Knowledge of how choice of foraging habitats, prey selection, and prey abundance are affected by warming water temperatures is needed to understand how climate change will affect productivity of consumers that live in association with coral reefs.

Loggerhead sea turtles Caretta caretta have been listed as threatened under the US Endangered Species Act since 1978, and a change in their listing status to endangered was recently under consideration. Estimates of adult population size are needed to evaluate population status, but include a number of uncertainties. A point estimate of loggerhead population size based on a nest count fails to convey the range of our uncertainty in the estimated number of individuals in a population. We developed distributions of adult female loggerhead subpopulation sizes for 5 subpopulations of the western North Atlantic, and for the western North Atlantic population as a whole. Distributions were derived by re-sampling from available nest counts (2001−2010) and data on breeding interval, survival and clutch frequency, each affecting the extrapolation of nest numbers to adult females. Our best estimate for the western North Atlantic adult female loggerhead population was 38 334 (SD = 2287) adult females. Confidence limits on estimates for the individual subpopulations ranged from a high of 45 058 adult females for Peninsular Florida to a low of 258 adult females in the Dry Tortugas. To reduce uncertainty in population estimates, research needs to focus on quantifying breeding interval and clutch frequency, especially in the less-studied subpopulations.

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Understanding the spatial movements of threatened marine species, such as sea turtles, is essential as a means of informing appropriate conservation management. Although novel techniques for tracking spatial movements are becoming more widely available (such as satellite tracking), simple techniques such as mark-release-recapture remain effective. A flipper tagging and recovery program in Cuba tagged 210 loggerhead turtles over 14 yr and recovered 7% of the tags between 2 d and 3 yr later (mean = 296 d). All but one turtle was recaptured in Cuban waters, and data showed limited movement of turtles between northern and southern coasts. A further 50 turtles were recovered that had been tagged in foreign projects, the majority of which were from the USA (but also Mexico, The Bahamas, Canary Islands and Spain). A range of life stages of loggerhead turtles are found in Cuban waters year-round, and given that Cuba has the second largest reef in the Caribbean, it likely provides foraging habitat for significant numbers of loggerhead turtles from at least 6 different countries.