Fecundity of the Norway lobsternephrops norvegicusin galicia (NW Spain) and a review of geographical patterns

Abstract

Abstract The fecundity of the Norway lobster Nephrops norvegicus in Galician waters (NW Spain) was estimated based on the number of eggs attached to the pleopods of ovigerous females in the initial, middle and final stages of the incubation period. The number of eggs per brood was related allometrically to the carapace length (CL), with an allometry coefficient ranging between 3.0 and 4.1 in the different incubation stages (P>0.05). Incubation lasts 6–7 months (from August–September to January–February) and the average egg loss is estimated to be 44% during this period. The mean fecundity (corresponding to a mean CL of 38.6 mm) was 2636 eggs in the initial stage and 1475 in the middle and final stages of incubation. The literature points to a high variability in the fecundity of the Norway lobster throughout its geographical range of distribution. Fecundity decreases with latitude in the NE Atlantic from Western Ireland to the South of Portugal, with the Mediterranean populations showing lower values than those in the Atlantic. However, considering the periodicity of spawning, which tends to be biennial towards the northern distribution area, the annual production of eggs per female may be similar in the different zones and may even increase towards the south. Egg loss during the incubation period has been estimated at between 32 and 68% for the different geographical areas.