Northwest Herring Acoustic Survey Report 24th June – 14th July, 2015

Abstract

The northwest and west coast (ICES Divisions VIaS & VIIb, c) herring acoustic survey programme was first established in 1994. The summer 2015 survey represents the eight in the new time series (est. in 2008). The survey was coordinated through the ICES Working Group of International Pelagic Surveys (WGIPS). The Irish component was carried out to cover the statistical rectangles between 53°30’-58°30' N and 12°-5° W as laid out in the WGIPS report (ICES, 2014). For 2015 only Irish data on herring distribution, abundance and age have been 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) herring stock is composed of two spawning components, autumn and winter spawners. Spawning covers a large geographical area and 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. The autumn spawning component, which mostly occurs within VIIb and VIaS, feeds along the shelf break area to the west of the spawning grounds. The larger winter spawning component is found further north in VIa. In VIaS, summer distribution extends from close inshore to the shelf break. Components of the winter spawning fish are known to undertake northward feeding migration into VIaN before returning in the winter to spawn along the Irish coast.