The PELGAS sea cruises aim at monitoring the Bay of Biscay pelagic ecosystem, in order to provide scientific data for the implementing of an ecosystemic management of Biscay living ressources. The spatial and temporal dynamics of small pelagic fish populations are specifically monitored, with a focus on anchovy and sardine populations. The cruise hence takes place in spring, when both species are spawning, to allow for the assessment of both eggs and adult stages.

The PELGAS ecosystemic cruise aims at collecting data at each level of the Biscay pelagic trophic chain. Data are collected continuously along parallel transects covering the whole Bay of Biscay, in order to thoroughly characterize the horizontal and vertical structures of the pelagic ecosystem. Multibeam and multifrequency echosounders provide real time information on the spatial patterns and abundance of pelagic organisms ranging from plankton to fish. Simultaneously, a Continuous Fish Egg Sampler provide complementary data on small pelagic fish eggs. The presence and abundance of seabirds and marine mammals are also continuously recorded.

Acoustic targets are punctually identified by fishing (pelagic trawling and plankton nets). CTD stations are actually performed over the whole Bay of Biscay to provide hydrological information. In situ measurements are compared to satellite and hydrodynamic models outputs.

The PELGAS cruise is part of the "Fisheries Information System" implemented by the "Biological and Environmental Resources" Ifremer department. Data are collected within the EU Data Collection Regulation framework and are used to assess the anchovy and sardine stocks within the ad-hoc International Council for the Exploration of the Sea (ICES) working groups. The sea cruise is internationally coordinated with Spanish, Portuguese and English cruises within the ICES WGACEGG working group. The survey also collects data on nutrients useful for descriptor D5 of the Marine Strategy Framework Directive. The numerous parameters collected during the PELGAS sea cruises will actually provide indicators to assess the good ecological state of the Biscay pelagic ecosystem, within the framework of the new EU directive.