Northwest Herring Summer Acoustic Survey Cruise Report June 19 - July 8, 2008

Abstract

The northwest and west coast (ICES Divisions VIaS & VIIb, c) herring acoustic survey programme was first established in 1994. A larval survey programme was initially carried out between 1981 and 1986. In the early 1990s, the ICES herring working group (HAWG) identified the need for a dedicated herring acoustic survey in this area (Anon, 1994). From 1994 to 1996 surveys were carried out on this stock during the summer feeding phase. In 1997 a two-survey spawning aggregation program was established covering both autumn and winter components. In 2004, a single spawning stock survey was carried out early in quarter 1 and continued until 2007, whereupon it was decided that this survey should be incorporated into the larger coordinated Malin shelf survey. This survey will be the first in a new time series and a step away from the traditional spawning stock surveys. The Irish survey will be carried out concurrently with the West of Scotland (MarLab) and Irish Sea surveys (AFBI) and was coordinated through the ICES Planning Group of Herring Acoustic Surveys (PGHERS). Combined survey data on herring distribution, abundance and age will be used to provide a measure of the relative abundance of herring within the Malin shelf stock complex. Survey data on stock numbers at age are submitted to the ICES Herring Assessment Working Group (HAWG) and used in the annual stock assessment process. The northwest and west coast (ICES Divisions VIaS & VIIb, c) herring stock is composed of 2 of spawning components (Autumn and Winter spawners) covering a large geographical area, which extends over a 4-month period from late September through to late March (Molloy et al, 2000). Traditionally fishing effort has been concentrated on spawning and pre-spawning aggregations. In Vlas, fishing begins in late Novemember and continues until late March (winter spawners). Further south in Vlllb, peak fishing takes place from October to December (Autumn spawners). The protracted spawning period of herring and the overlap between the two spawning stocks in this area (October to February) is highly dynamic with variations between annual spawning events of up to 3 weeks. Up to 40 vessels commonly participate in the fishery, many of which are based in the Co. Donegal port of Killybegs. The fleet is made up of 20 RSW (Refrigerated Seawater) vessels of 40-70m in length; 20 polyvalent trawlers 10 of which are vessels of 22-40m and 10 of less than 25m.