Browsing by Author "Amorim, Antonieta"
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- Deep stocks avoid competition migrating horizontal and vertically: The example of two scabbardfishes (Aphanopus spp.) targeted by long-liners in grounds next to an oceanic archipelagoPublication . Vasconcelos, Joana; Henriques, Paulo; Sousa, Ricardo; Amorim, Antonieta; Delgado, João; Riera, RodrigoFishing is occurring all over the globe, with an increase trend of exploiting deep stocks. Several species are currently targeted from the deep ocean, and some artisanal fisheries developed fishing gears, e.g. long lines, with limited impact to the environment but scarce information is available on biological aspects of these exploited stocks. In the Macaronesian region and specifically in Madeira archipelago, two Aphanopus sympatric species have been extensively exploited for decades but no detailed information is available on the spatial and vertical distribution of both species (Aphanopus carbo and Aphanopus intermedius). Currently, they represent an important percentage of landings from artisanal fishermen of Madeira (27% of the total catches in 2017). We herein observed that they showed a pattern of depth segregation, where adults of both species are more abundant (ca. 80%) at deeper seafloor (> 2500 m). A. intermedius was more numerous in fishing areas with greater seafloor depth (> 4500 m) compared to A. carbo. This pattern may be explained by a food source overlap between both species, and also the vertical segregation within the same species may be considered as a pattern to avoid cannibalism. Also, migration patterns were found in both species being more pronounced for A. intermedius where > 86% of individuals were collected offshore (> 12 n.m.). The present results constitute a step forward to start developing integrative management actions to preserve stocks of both species in the medium and long term in the study region.
- Two sympatric, not externally discernible, and heavily exploited deepwater species with coastal migration during spawning season: implications for sustainable stocks management of Aphanopus carbo and Aphanopus intermedius around MadeiraPublication . Vasconcelos, Joana; Sousa, Ricardo; Henriques, Paulo; Amorim, Antonieta; Delgado, João; Riera, RodrigoSeveral artisanal fisheries target deep species. These stocks are highly sensitive to overfishing because of their slow growth and late maturation. This vulnerability is higher if species concentrate during spawning season in coastal areas, as occur with scabbardfish (Aphanopus spp.). We herein explore if two Aphanopus species (A. carbo and A. intermedius) that coexist show migration patterns to coastal areas during spawning. We analysed specimens of both species throughout 4 years (2014-2017) in a weekly basis and compare morphological parameters to the distance of the coast [coastal (< 12 nm) vs. offshore (> 12 nm)]. Both species showed coastal patterns of migration during the spawning season (October-December), with 65.90% of total specimens of A. carbo and 51.60% of A. intermedius being caught at < 12 nm during this season. Fishing events were also more numerous at < 12 nm to the coast during spawning season (46.6%) relative to non-spawning season (32.6%). A series of management measures, e.g. October 46 December season, were developed to preserve Aphanopus stocks in the NE Atlantic Ocean.