Biological condition and population structure of benthopelagic shrimps in the Galicia Bank (NE Atlantic): Intra- and interspecific patterns

Few studies examined species or ecosystem dynamics on seamounts/banks. The Galicia Bank (GB), the deepest marine Special Area of Conservation in the Spanish Natura 2000 network, is considered a conservation priority because of its highly vulnerable habitats, such as cold-water and bamboo corals. The biological conditions and population structure of benthopelagic shrimps and their relationship with environmental conditions were analyzed during three expeditions over three years. Shrimps were collected by trawling. The gonadosomatic index (GSI) and nutritional condition (hepatosomatic index [HSI]) of shrimps were highest at the summit and deepest depths (>1500 m) sampled, whereas at intermediate depths between ca. 900–1500 m, these values were low. The intermediate depths around ca. 1000 m are influenced by the core of the Mediterranean Outflow Water (MOW), which is characterized by high salinity and low O2 concentrations. The highest GSI were recorded in species (Aristeus antennatus, Plesionika martia) distributed at summit, associated with higher Chl a 1–2 months before sampling at surface. The species with the highest HSI were also linked to Chl a 1–2 months and with higher %OM (generalized additive models, GAM, results). Overall, the studied shrimp species showed viable populations on GB, with reproductors/spawners more markedly distributed over the summit (ca.