Sustainable harvesting of coco de mer, Lodoicea maldivica, in the Vallée de Mai, Seychelles

Abstract

The coco de mer palm Lodoicea maldivica, endemic to the Seychelles, is a flagship species for tourism and conservation. It bears the world's largest seed for which it is currently heavily exploited across its limited range, and it is clear that harvesting at current levels cannot be maintained indefinitely. Biologically informed harvesting protocols are therefore required to move towards sustainable management that secures the long-term viability of the population and the revenue that it currently generates. Demographic modelling using population matrix models is a useful tool in these efforts as it identifies both the life stages with the strongest influence on population dynamics as well as the consequences of current use intensities. Here we provide an initial population model based on data currently available to assess the status of the largest L. maldivica population in the Vallée de Mai World Heritage Site. We estimated transition probabilities and constructed matrices to estimate the populations’ growth rate under current and alternative harvesting regimes, taking into account uncertainty regarding adult mortality and lifespan. Model projections of the population under current harvesting intensities forecast a marked decrease in the proportion of juveniles in the population and a gradually declining population over the next 200 years. Population growth rates were most sensitive to adult survival, reflecting the long generation time of this species and the remaining uncertainty in this respect. Based on this preliminary model we propose a precautionary sustainable harvesting limit for L. maldivica and discuss the challenges and opportunities of its management, including recommendations for future data collection.