The semi-wild mariculture of Caribbean King Crab (Maguimithrax spinosissimus) for coral reef restoration

Aquaculture has traditionally focused on supporting human food production, but there is a growing need for aquaculture associated with environmental restoration. For example, the in situ and ex situ rearing of corals for coral reef restoration is now implemented worldwide, but its success is limited by the lack of reef herbivores to combat the phase shift from coral-to-macroalgae-dominance on reefs, especially in the Caribbean. Laboratory-based aquaculture of some reef herbivores is possible but labor-intensive and insufficient to supply the numbers needed for large-scale restoration. We examined whether this bottleneck could be alleviated by the semi-wild mariculture of the Caribbean King Crab ( MaguiMithrax spinosissimus )in saltwater quarries for subsequent use in coral reef restoration in the Florida Keys, Florida (USA).We surveyed the physico-chemical characteristics of 16 saltwater quarries in the Florida Keys relative to conditions in the wild and, in four quarries where crabs occurred, we examined crab population dynamics in comparison to that in the wild. Water chemistry and the availability of food (macroalgae) and crevice shelters were suitable for crab mariculture down to depths of at least 6 m. Herbivore competitors and predators were few in quarries, and there was no difference in the population size structure, fecundity, predatory mortality, or health of crabs in quarries compared to that in the wild. Therefore, the low-cost semi-wild mariculture of large numbers M. spinosissimus is feasible in saltwater quarries and could alleviate a logistical bottleneck to herbivore restoration on Caribbean coral reefs. • The semi-wild mariculture of herbivorous crabs within saltwater quarries for use in coral reef restoration appears feasible. • Crabs ( MaguiMithrax spinosissimus ) naturally occurred in 4 of the 16 quarries surveyed in Florida. • Bio-physico-chemical characteristics of all saltwater quarries surveyed were suitable for crabs. • Population structure, fecundity, mortality, and health of crabs in quarries was similar to that in the wild.