Spider crab

The spider crab (lat. Maia squinado) belongs to the order Decapoda and the family Majidae. Known for its distinct appearance and long limbs, this crustacean is a well-studied species in the Atlantic and Mediterranean marine environments, often interacting with human-made structures such as aquaculture installations.

The primary targets for this species within the context of marine agriculture are shellfish farms, specifically those cultivating oysters and mussels. As the crab is naturally attracted to reefs and structured habitats, artificial aquaculture beds often provide an ideal environment for foraging and protection, leading to conflicts with farmers.

The biology of Maia squinado involves a metamorphosis process where larvae spend time in the water column before settling onto the seabed. As they grow, they undergo regular molting cycles. Their diet is diverse, consisting of algae, organic detritus, and, crucially, small mollusks that inhabit the local ecosystem.

Damage caused by the spider crab is two-fold: physical destruction of netting and gear used to secure shellfish, and direct predation on the stock. Large densities of crabs can lead to significant mortality rates in juvenile mollusk populations, impacting the overall yield and economic efficiency of the farm.

Recommended protection and management strategies include:

• The use of high-durability, anti-predator netting designed to withstand crustacean claws.
• Regular inspections of underwater infrastructure by divers or remote-operated vehicles (ROVs).
• Implementation of baited trap lines to remove high numbers of crabs from the immediate farming vicinity.
• Strategic site selection to avoid known seasonal aggregation zones for this species.