ISADO - Identification des frayères du Détroit du Pas-De-Calais et des zones marines adjacentes

Spawning is an essential element of the life cycle of marine fish. Fish eggs present a high natural mortality, which makes them a particularly vulnerable stage of fish development.With more and more fish species becoming over-exploited, commercial fisheries are increasingly sensitive to fluctuations in the recruitment of young individuals to the spawningstock. Egg data were collected in the southern part of the North Sea and Dover Strait using a Continuous Underway Fish Egg Sampler(CUFES). With co-funding from the Interreg IIIa Programme, the ISADO (Identification of the Spawning Areas in the Dover Strait and adjacent marine areas) project processed800+ egg samples, with the development of a taxonomic identification key. The spawning areas of seven fish species were mapped using geostatistics, and the associated spawning habitats were modelled using generalised linear models. The egg abundances of a further eight fish species were also mapped. Preliminary work was also undertaken on the use of molecular techniques (genetic markers) and automated image analysis (ZooScan) so as to improve the accuracy and/or the speed of taxonomic egg identification and counting. It is hoped that the results presented in this richly illustrated final report will contribute to a better knowledge and understanding of spawning areas and their associated habitats, so that action can be taken to preserve them in the longterm.