Celtic Sea Herring Acoustic Survey RV Celtic Explorer 1st – 21st October 2006

Abstract

In the Celtic Sea and ICES Division VIIj the herring fishery is divided into 3 main catching seasons. In quarters four and one, the fishery is focused on autumn and winter pre-spawning and spawning aggregations. In the 2004/05 season 34 vessels participated in the fishery, ranging from small dry hold polyvalent vessels (<20m) to purpose built RSW (Refrigerated seawater) vessels of 23-40m. Single and pair midwater trawling are common, with the latter representing the preferred catching method. In recent years a quarter-3 summer fishery has developed targeting offshore feeding aggregations, 78nmi (nautical miles) offshore on the Labadie Bank. This offshore fishery is restricted to the RSW fleet on the grounds of product quality delivered to processors. The 2006 autumn survey is the most comprehensive survey carried out in the current time series. The geographical extent of the annual 21 day survey was extended further offshore to include areas to the south of the main coastal spawning grounds to target winter spawning fish on an inward spawning migration. Spatial resolution of acoustic transects were increased over the entire south coast survey areas, with a special focus on spawning grounds throughout the survey confines. The acoustic component of the survey was complimented by a continuation of the detailed hydrographic work first established in the Celtic Sea in 2004.