Ecosystem overviews

Bay of Biscay Ecoregion

Pressure: Selective extraction of species


Fishing, and to a lesser extent tourism and recreation, are the main activities contributing to pressure in this ecoregion. Both demersal and pelagic commercial fisheries occur in most parts of the ecoregion. Recreational fishery in coastal areas is becoming a relatively important activity, and is in some cases taken into consideration for the management of marine fisheries. This pressure has four main effects on the ecosystem and its components; these are described below.

​Impacts on commercial stocks

Figure 4 shows the historical evolution of fishing mortality relative to reference points by fish guild in the Bay of Biscay and the Iberian Coast ecoregion. A general decrease in fishing effort in the region (in many cases because of a reduction in the fleet) has contributed to an overall decline in the fishing mortality (F) of commercial fish stocks since 1988. The mean F is now closer to the level that produces maximum sustainable yield (MSY).

Stocks of small pelagics like sardine and anchovy are highly influenced by natural recruitment variability and are therefore prone to periodic collapses linked to oceanographic variability. These stocks are closely monitored and regulated by strict management.

The conservation (sustainability) status of cephalopod populations varies depending on the particular subregion, with declining catch per unit effort (CPUE) of octopus species in Galicia and long-finned squid Loligo forbesi off western Portugal, and increasing CPUE of octopus species in western Portugal and squid species in the southern Bay of Biscay.

Some coastal waters in the ecoregion have fisheries targeting resident immature eels, or migrating spawners.

For detailed information on fishing activities in this ecoregion, see the Bay of Biscay and Iberian Coast Fisheries Overview.

​Impact on threatened and declining fish species

Stocks of several fish species have been adversely affected by fishing and are now on the OSPAR list of threatened and declining species (see full list below). These include the sturgeon Acipenser sturi, European eel Anguilla anguilla, gulper shark Centrophorus granulosus, skates and rays like Dipturus batis, Raja montagui, and Rostroraja alba, spurdog Squalus acanthias, and salmon Salmo salar. Although there are no TACs for these species and some are prohibited to be landed under EU law, several species are vulnerable to existing fisheries. The Common skate, and less often spurdogs, are caught as bycatch in demersal trawl fisheries while deep-water sharks are caught in the mixed deep-water trawl fishery.

​Impacts on foodwebs

Fishing can disturb the foodweb. Predator–prey relationships can change, depending on the species and on the amount of food (prey) that is available for a given predator. Poor management of fishing for one species could have an adverse effect on the whole foodweb. Multispecies assessment methods can account for some of these interactions and guide appropriate management measures.

Indicators like the large fish indicator (LFI) index (describing the proportion – by weight – of the demersal fish community on survey catch larger than regional length thresholds) can be used to monitor changes in the fish populations. In the Bay of Biscay, the LFI index has shown a positive temporal trend since the year 2000 (Figure 5).

​Impacts on seabirds and marine mammals

​Observation of marine mammal bycatch has occurred in certain fisheries off France and in a few off Galicia. Harbour porpoises Phocoena phocoena are being caught as bycatch off Iberia in set-nets to the extent that the local population of the species may become extinct. Set net fisheries and pelagic trawls, particularly those for sea bass Dicentrarchus labrax, have caught common dolphins Delphis delphinus and striped dolphins Stenella coeruleoalba. Seabird bycatch seems likely to be part of the reason for the loss of the Iberian form of the common guillemot Uria aalge and some other seabird species.

Print this pagePrint it Request newsletterSend to Post to Facebook Post to Twitter Post to LinkedIn Share it
​​ Figure 4. Time-series of annual average for the relative fishing mortality (F to FMSY ratio) by fisheries guild for benthic, demersal, crustaceans, and pelagic stocks. Table A1 in the Annex details which species belong to each fish category.

Figure 5. Time-series of the large fish indicator (LFI) in the Bay of Biscay (ICES, 2013a). Click image to enlarge.
Figure 6. Time-series of the large fish indicator (LFI) in Portuguese waters (ICES, 2013a). Click image to enlarge.
c FollowFollow Focus on ContentFocus on Content
HelpGive Feedback

Bay of Biscay Ecoregion

International Council for the Exploration of the Sea (ICES) · Conseil International pour l'Exploration de la Mer (CIEM)
ICES Secretariat · H. C. Andersens Boulevard 44-46, DK 1553 Copenhagen V, Denmark · Tel: +45 3338 6700 · Fax: +45 3393 4215 ·
Disclaimer Privacy policy · © ICES - All Rights Reserved