The Atlantic Spinous Spider Crab (Maja brachydactyla) has increased in abundance in the coastal waters of North Wales over recent decades. Despite an array of anecdotal reports regarding the species in this region, there is very little research providing an insight into this, and substantial knowledge gaps regarding the ecology of the species. There is presently a low commercial market for the species in North Wales. This study uses local knowledge alongside 3 key sampling methods; one static gear (local pot fishery bycatch), and two mobile gear surveys (Newhaven dredge and 4m bottom trawl), to provide the first species-specific study in North Wales, with a total of 1118 individuals sampled from April to November 2022. This study found the highest abundances of M. brachydactyla from southern Cardigan Bay to North of the Llŷn Peninsula, with lower numbers of individuals in Liverpool Bay to the north. Estimated sizes at maturity for this study are 101mm (L50) and 115mm (L90), with ovigerous females present throughout the sampling period (April to September 2022). Gear type had a significant impact on the ratio of sexes caught, with baited pot fishing presenting significantly more male crabs than in mobile gear surveys. It is recommended that further research uses non selective gear types for population sampling. Using information voluntarily provided by industry partners, this study found that spider crabs are generally perceived negatively by fishers, viewed as a bycatch species. There are concerns the increased abundance of M. brachydactyla may be impacting benthic communities and commercially important species in North Wales. Observations of in-pot depredation of small lobster (Homarus gammarus) may indicate the possible impacts of spider crabs within the local crustacean fishery.