Here today, here tomorrow: Beached timber in Gabon, a persistent threat to nesting sea turtles

notes:types: JOURThe African country of Gabon has seen decadal increases in commercial logging. An unforeseen consequence of this has been that many coastal areas, including several National Parks and Reserves, have suffered severe pollution from beached timber. This has the potential to adversely affect nesting sea turtles, particularly the leatherback turtle (Dermochelys coriacea) for which Gabon constitutes the world’s largest rookery. In this study, we analyse aerial survey data (2003, 2007 and 2011) to determine the temporal persistence and spatial extent of beached timber, and by integrating spatial data on nesting, ascertain regions where beached timber poses the greatest threat to nesting leatherback turtles. There was no marked difference in the number of beached logs recorded across the study area during the period, with 15,160, 13,528 and 17,262 logs recorded in the three years, respectively. There was, however, a significant difference in abundance of beached logs among geographical areas. Analysis highlighted two coastal areas where nesting leatherback turtles were likely to be at greatest risk from beached timber. At one such site, Kingere, within Pongara National Park, where both logs and turtle densities are high, monitoring in 2006/2007 and 2007/2008 suggested that between 1.6% and 4.4% of leatherback turtles could be entrapped at this site. Given the dynamic nature of Gabon’s coastal environment, and the potential limitations of aerial surveys, densities of beached timber could be greater than this analysis reveals. We also propose, that despite recent export restrictions of whole logs, their environmental persistence potentially represents a long-term problem

Conservation‐relevant reproductive parameters from long‐term tagging of two globally important sea turtle nesting aggregations in Central Africa

Assessing abundance and monitoring ecology and population trends are of critical importance for animal species of conservation concern. For sea turtles, annual nest counts represent the most common method of estimating population size. However, to develop a better understanding of population trends, these data need to be complemented by other reproductive parameters, which are lacking for many nesting populations across central Africa.To this end, an intensive capture-mark-recapture programme was conducted spanning 21 years (1997-2018) in the most important nesting sites on the Atlantic coast of central Africa (Gabon and Congo) for leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea) sea turtles.A total of 18,105 encounters of 14,109 D. coriacea individuals and 2678 encounters of 2427 L. olivacea individuals were recorded. Biological and technical parameters such as clutch frequency, inter-nesting interval, remigration interval, annual survival rate, somatic growth, size trends, tag loss and number of annual nesting females were estimated through a variety of methods and models.The study detected a decline in body size and low survival probability (not due to tag loss) in both species but no clear decline in estimated annual number of nesting females. High fidelity to nesting sites (<30 km for both species) implies that the current conservation strategy, protecting the main nesting areas, could be effective.We recommend that local conservation managers promote: (i) continued monitoring of the nesting activity of the two species through capture-mark-recapture programmes; (ii) continued nest counts at long-term monitoring sites, which may also detect possible spatial shifts; and (iii) strengthening of cross-border cooperation between Gabon and Republic of the Congo given the observed connectivity between nesting sites of the two countries