Publication on data.gouv.fr
Species and habitats - Clupea Harengus - Larvae - < 15mm - IBTS Annual abundance in January (2008-2011)
Fish larvae were collected during the night using a MIK (Methot Isaac Kidd) net (2m diameter, 500 um mesh). Abundances were expressed in term of number of individuals per 5000 cubic meter (ind.5000m-3). For clupeidae (herring and pilchard), gobiidae and ammodytidae, abundances were log-transformed (log10(x+1)) prior to analysis whereas for pleuronectidae and syngnathidae, abundances were recoded in term of presence-absence.
The survey extends from the Eastern English Channel to the south of the North Sea, which corresponds to ICES divisions VIId and IVc. The study area is divided into rectangles of 15° latitude and 15° longitude using a systematic sampling strategy. The sampling gear is a high opening bottom trawl well adapted for catching demersal species, with a 10 mm mesh size (side knot) for catching juveniles. This sampling gear is polyvalent and is well adapted to the varying seabed types encountered in the study area. The fishing hauls are chosen using professional fishing plans or found by prospecting. The fishing method is standardised: sampling stations have been each year at similar locations and identical sampling gear is used. At each sampling station, all the fish species are sorted, weighed, counted and measured.
Purpose: not specified