Fish diversity is high in this ecoregion, reflecting its wide latitudinal dimension. The pelagic habitat is mainly dominated by sardine, anchovy, mackerel, horse mackerel, and blue-whiting Micromesistius poutassou. Some migratory species also appear in specific periods, such as tuna species (albacore Thunnus alalunga and bluefin Thunnus thynnus), which feed upon smaller pelagic fish. Hake is the most abundant predator species in the demersal community. Anglerfish, megrim, and sole are more abundant in the northern part of the ecoregion. Cold-water species such as whiting Merlangius merlangus and pollack Pollachius pollachius only occur north of Portugal. Skates, sharks, and deep-sea fish occur over the continental slope and in the deeper parts of this ecoregion.
The recruitment to the European eel (Anguilla anguilla) population has declined sharply in recent decades. For evaluated stocks, the spawning‑stock biomass (SSB) is above reference points (Btrigger). Figure 10 displays the historical evolution of spawning‑stock biomass relative to reference points by fish guild in the Bay of Biscay and the Iberian Coast ecoregion, and shows an increase in the spawning-stock biomass that has been observed since 2002.
Within this ecoregion the topographic diversity and the wide range of substrates result in many different habitats for cephalopods. In this region, the most abundant and commercially exploited species are long-finned squid Loliginidae and cuttlefish Sepiidae. Abundance of short-finned squid Ommastrephidaeincreases westwards towards Galicia, and decreases to the south of the Iberian coast. Octopodidae are abundant and heavily exploited along the Iberian coast by a large artisanal fleet, with concomitant social relevance. There are indications of a decline in octopus biomass index in Galicia and an increase off western Portugal. Stocks of both long-finned squid and short-finned squid have declined in the southern Bay of Biscay.
Threatened and declining fish and shellfish species in the Bay of Biscay and Iberian Coast ecoregion according to OSPAR:
Figure 10: Time-series of annual average for the relative spawning stock biomass by fisheries guild for benthic, demersal, crustaceans, and pelagic stocks. Table A1 in the Annex details which species belong to each fish category.