Costa Rica is an important country for turtle conservation and famous for the spectacular mass-nesting (arribada) behaviour witnessed on many of its beaches. Ostional, a small town on the Pacific coast, is a particularly important location for this behaviour. It is a nesting beach for Leatherback sea turtles, Green sea turtles and the mass-nesting Olive Ridley sea turtles.
I spent some time in Ostional in 2013 working mainly on Leatherback monitoring and conservation. While there, I witnessed firsthand the debate about the highly contentious but legal egg-harvesting program (EHP). This program is only applicable during arribada events and has been hotly debated in conservationist circles. Outside of the EHP it is illegal to harvest and sell turtle eggs in Costa Rica. Poaching is a common and dangerous practice. In fact, a conservationist was murdered last year by poachers on one of the protected beaches in Ostional (Aldhous, 2013). Turtle eggs are seen as delicacies and many cultures view them as aphrodisiacs. Harvesting is one of the major threats to Olive Ridley sea turtles globally and the trade is particularly virulent in Latin America.
The EHP is heavily regulated and follows strict international and domestic laws (Campbell et. al. 2007). For the first two days of every arribada the local community is allowed to harvest as many eggs as they want from the turtles nesting in daylight on the beach. This behaviour serves two very important purposes. Firstly, it provides a financial boost to an otherwise impoverished community with economic benefits that flow into the region through increased schooling, health facilities and trade. The managed harvest also allows the remaining eggs to be protected and that means an increase in turtle numbers and an increase in ecotourism, a billion dollar industry (Gonzalez, 2013) in Costa Rica. The community actively engages in the protection of endangered species and actively aids authorities in conservation efforts (Campbell, 1998). When I was living in the town, I found that every family in the community participated in the local nightly patrol of the beach to ensure that illegal poaching was minimised.
From an ecological perspective, the harvesting also helps the turtle community. During arribadas Olive Ridley females have been observed digging up nests from other females and destroying these eggs in the process. These later laying females can destroy most of the earlier nests within hours, and therefore the eggs harvested by the Ostional people were unlikely to make it to full term. Broken eggs also provide the perfect starting point for bacteria which can penetrate other untouched eggs in the area, infecting a nest and ensuring that none of the eggs hatch (Honarvar et. al., 2011). Harvesting the earlier nests lowers the prevalence of nest-destroying bacteria. Similarly, whole nests attract fewer predators than broken nests and there is a lower likelihood of predators finding intact nests when there are no broken ones in the area. The harvesting done by the local people not only improves their lives but also lowers the impact of later nesting females on the beach population.
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Aldhous P (2013) Turtle conservationist murdered in Costa Rica, New Scientist, accessed http://www.newscientist.com/article/dn23639-turtle-conservationist-murdered-in-costa-rica.html#.U14v5FWSyQ0 .
Campbell LM (1998) Use them or lose them? Conservation and the consumptive use of marive turtle eggs at Ostional, Costa Rica, Environmental Conservation 25(4), 305-319.
Campbell LM, Haalboom BJ, Trow J (2007) Sustainability of community-based conservation: sea turtle egg harvesting in Ostional (Costa Rica) ten years later, Environmental Conservation 34(2), 122-131.
Gonzalez A (2013) Visitas turisticas en el 2012 fueron las mas altas de los ultimos cinco anos, La Nacion, accessed http://www.nacion.com/archivo/Visitas-turisticas-altas-ultimos-anos_0_1328067181.html (translated online).
Honarvar S, Spotila JR, O’Connor MP (2011) Microbial community structure in sand on two olive ridley arribada nesting beaches, Playa La Flor, Nicaragua and Playa Nancite, Costa Rica, Journal of Experimental Marine Biology and Ecology 409(1-2), 339-344.