Invasive alien crabs can be used for marine aquariums — turning a threat into profit

Abstract

The present study demonstrates that specimens of the grapsoid crab Percnon gibbesi invading the Mediterranean can replace those being collected in the species home range to supply the European marine aquarium trade. Although P. gibbesi is currently ranked among the “100 worst” invasive alien species in Europe, thousands of specimens of this crab are still collected every year from the western Atlantic and shipped to Europe as “reef janitors” for marine aquariums. This work analysed the acceptance of Mediterranean P. gibbesi by European marine aquarium retailers, which, as expected, were unable to distinguish western Atlantic from alien P. gibbesi. Hobbyists claimed to prefer alien specimens, but only if these displayed an identical (or lower) retail value than those of the western Atlantic. Although a selective fishery on young recruits and female P. gibbesi will not eradicate or even stop the dispersal of this highly successful invader, it will certainly generate a new income source for local fishermen and probably help to alleviate the fishing pressure on potentially over-harvested stocks of P. gibbesi in its home range.