This species may show fast growth for a deep-sea fish, maturing at about 3 to 4 years and with longevity of 12-24 years [99,100], which could help to explain its apparent sustainability. Another reason is that the fishery used hook and line gear [101].In the past, the complexity of Madeira’s seafloor prevented bottom trawling. Now that trawlers can fish on steep slopes, the Portuguese government and regional authorities have prohibited use of trawls in both Madeira and the Azores. This became an EC regulation (EC Reg. 1568/2005) under the new Common Fisheries Policy to foster conservation of sensitive deep-sea habitats and species [102].Black scabbardfish fisheries are still artisanal in Portugal but are much more industrialized elsewhere (e.g., French deepwater freezer trawler fisheries in northern European waters) [103],
where CPUE shows a population decline [104]. For this reason, the international Council for the Exploration of the Sea (ICES) has asked for significant reductions in fishing effort. Present landings in northern Europe are probably maintained by serial exploitation of new fishing grounds. But in waters between the Azores and the Canary Islands, artisanal longline black scabbardfish fisheries seem to have stable catches and biomass, and may remain so if fishing effort does not increase [104