Stock structure with ICES are VI is uncertain. Nephrops (or Norway Lobster) stocks area assessed as Functional Units (FU) based on growth parameters and other factors. Within FU 13 there are two distinct populations, one for the Firth of Clyde and one in the Sound of Jura (ICES 2016)(ICES 2016).  Until recently these were treated separately for assessment purposes as there are differences in growth rates for these to components. However, in a recent update advice and some aspects of the reference points were analyzed combined. This is attributed to the fact that landings from the Firth of Clyde and the Sound of Jura are considered inseparable (ICES 2016)(ICES 2016).