Assessing the Ecological and Socio‑Economic Impacts of the Invasive Bleu Crab Callinectes sapidus Using Local Knowledge and Field Surveys in Eastern Morocco

The Atlantic blue crab (Callinectes sapidus) is an invasive alien with recent populations developing along the Mediterranean shoreline of Morocco's Oriental region. This study evaluates its ecological and socio-economic impacts, with a special emphasis on artisanal fisheries, in three Ramsar-designated sites, i.e., Cap-de-l’Eau–Saïdia, Nador–Marchica Lagoon, and Al Hoceima–National Park. Field observations, questionnaires, and semi-structured interviews with fishing operators and restaurant owners were used to obtain data. Results show that blue crab presence peaks in the summer and its habitat is connectivity-dependent: higher abundances occurred in semi-open marine systems such as lagoons and estuaries. The enormous majority of fishermen (91%) consider the species as harmful because it preys on native fauna. Changes in benthic community inventories have been documented through ecological assessments. Impacts were assessed using the Environmental Impact Classification for Alien Taxa (EICAT) and the Socio-Economic Impact Classification for Alien Taxa (SEICAT), showing major disturbances to ecosystems and local economies. Although there is some recognition of commercial potential among fishermen and restaurant owners, they often face hurdles such as limited demand, low market prices, lack of culinary knowledge and absence of specific fishing gear. We conclude on the multifaceted challenges that the blue crab invasion presents, and highlight the necessity of an integrated management approach, that accounts for the invasive impacts while investigating the blue crab’s value as a fishery resource.