A crab invasion can turn a familiar day at sea into damaged nets, longer hours, injuries, and less money. But the same animal creates a very different crisis in two nearby European fishing regions. The recent and growing invasion of the blue crab is causing damage in European aquatic ecosystems and affecting fishermen’s livelihoods.

The study explores these economic and social effects among small-scale fishermen in Apulia in southern Italy and Algarve in southern Portugal. The study compares the blue crab’s socioeconomic implications for small-scale fishing in Apulia and Algarve, focusing on interactions with the main craft fishing professions.

It examines catch quality, damage to nets and fishing equipment, interactions with other species, and changes related to fishery areas. That comparison matters because understanding local conditions is crucial for creating management measures that protect the marine ecosystem and strengthen coastal communities.

Information came from direct interactions with fishermen working around the Lesina lagoon in Apulia and the Ria Formosa lagoon and Guadiana Estuary in Algarve. A rapid survey found that fishermen who had already encountered the invasive crab numbered thirty-three in Apulia and thirty-six in Algarve.

The two areas had markedly different perceptions of how the invasion affected fishermen’s well-being. In Apulia, every respondent confirmed damage to nets, and increased costs were linked to damaged gear, greater fuel use, and the need for new equipment.

Physical harm from the crabs was also reported by fishermen in Apulia. In Apulia, the invasion affected nets, physical safety, other commercial species, catch quantities, working hours, costs, and income. In Algarve, net damage was lower, while physical harm, longer hours, higher costs, and reduced income stood out.

An everyday comparison is a shop receiving a new product without the right shelves, packaging, or customers: the product may be valuable, yet the business still pays the cost of adapting. In Algarve, nearly all interviewed fishermen sell the crabs, while only a minority in Apulia recognize their commercial value.

Algarve has a tradition of crab fishing, with an abundant and widely consumed product. Apulia has no established supply chain, and fishermen lack appropriate gear. Blue crabs are affecting fishermen’s livelihoods in different ways: in Apulia, damaged nets stand out as especially serious, while in Algarve the added workload is more prominent.

The impacts reach beyond earnings, threatening equipment, catches, other valuable species, and personal safety. In Apulia, the study identified four clusters of fishermen based on their responses to the impacts of the blue crab invasion, grouping participants with similar response patterns.

That means the invasion did not affect every fisherman in exactly the same way, even within the same region. The study relies on fishermen’s perceptions, which can vary with the presence or absence of the blue crab and with the timing of interviews.

More detailed analysis of the damage still requires further exploration. Future research should test proposed solutions, evaluate how fishermen and markets adapt, and examine alternative fishing methods and ways to reuse crab by-products.

Better long-term measures could evaluate whether these strategies work and promote sustainable fishing in affected areas, while more data on crab abundance and density would clarify the invasion’s pressure. The damage depends not only on how many crabs are present, but on whether fishermen have suitable gear and a market for the catch.

That difference points toward practical local solutions.