Norway Lobster (Nephrops norvegicus)

Fishery

The western Irish Sea mud belt supports the Nephrops stock ‘Functional Unit 15: Irish Sea West’. Landings of Nephrops from this Functional Unit are dominated by Northern Ireland registered vessels (approx. 6,000 tonnes per annum) and the Republic of Ireland (approx. 2,000 tonnes per annum) using otter trawls. Despite a significant proportion of the FU15 biomass being within Isle of Man territorial waters (~10%), only a small amount of landings are reported by Isle of Man registered vessels. Nephrops occur in high densities (1.1 per m2), which is reported to result in a smaller length distribution of the population. The minimum conservation reference size is 20 mm CL in Functional Unit 15. Nephrops is an EU-quota species, and therefore fishing opportunities are limited to those with quota access.

Life Cycle

The catchability of Nephrops to trawling is highly dependent on their emergence behaviour. Their emergence from the burrow for feeding or mating is triggered at a specific light intensity, and impacted by depth, season and water parameters resulting in emergence patterns covering diurnal (deep stocks), nocturnal (shallow stocks) or crepuscular (medium depths).

Habitat & Distribution

Nephrops is a clawed lobster that is largely defined by the burrowing habitat of the species, which is found in abundance in the soft sediment below 50 m to the west of the Isle of Man.