There has been a particular focus on defining the parameters of importance for assessment and management, such as growth and maturation size as well as size frequencies at different depths and sediment types.  There are variations in the biological parameters of Nephrops from different grounds in the North Atlantic East and in the Mediterranean, which have received a lot of attention over the years (e.g.; (Farmer 1975); (Hoydal 2014); (Ulmestrand 2001)).

Differences in N. norvegicus population demographic structure among geographical sectors, as well as in total mortality, appear to be highly related to different exploitation levels (Abelló et al. 2002)

Low levels of differentiation were found between Norway lobster populations and there were no signs of an Atlantic–Mediterranean divide or of an isolation-by-distance scheme of differentiation (Stamatis et al. 2004). Stocks are assessed at a Functional Unit (FU) level, which corresponds to a specific habitat area. However, these units are managed at ICES Division level.

There are several FUs in the North Sea: i) Northern area: Noup, Moray Firth, Fladen Ground  and Norwegian Deep, ii) Central area: Firth of Forth, Devil’s Hole, Farn Deeps, Off Horn’s Reef and Botney Gut – Silver Pit.

Thus, Nephrops management areas fall within the TAC regime of the European CFP, although allocated TACs do not coincide totally with the Functional Units.