A proposed combined groundfish survey index for Cod (Gadus morhua) in the Celtic Sea ICES Area VIIe-k

Management of cod in the Celtic Sea (ICES VIIe-k) has been problematic for some time, in recent years largely related to poor information around discarding and high-grading practices. No analytical assessment was performed between 2008 and 2009 and only an exploratory assessments in 2010 - 2011.  
Two of the surveys used as tuning fleets in the assessment provide virtually total coverage of the VIIe-k assessment area. The French EVHOE survey covers the area from the southern Bay of Biscay up to the Irish south coast. The Irish Groundfish Survey (IGFS) extends from the Irish south coast to cover VIIg & j north, as well as VIIb in the west, included in the TAC area (Fig. 1). The current time series extends back to 2003 for the IGFS and from 1997 for the EVHOE survey.
Given the shortcomings in commercial data for this stock, the intention here is to evaluate whether a combined index of IGFS and EVHOE survey data provided a more precise index as well as just improved coverage.