Regional variability in reproductive traits of European hake Merluccius merluccius L. populations

Multiple comparison analysis of batch fecundity (BF) and spawning fraction (SF) of European hake (Merluccius merluccius L.) stocks was carried out over two different regions during a 2-year-period. Female specimens caught by commercial fishing vessels were sampled on a monthly basis during the main spawning season from January to June in the Bay of Biscay (BoB) and on the Galician Shelf (GS). Spatial and temporal studies revealed that BF and the prevalence of spawning females were significantly lower in the BoB than on the GS. However, the data displayed the same seasonal pattern for both regions.The results are inconclusive as to whether homogeneity between the European hake stocks in each region exists. The results do, however, suggest the existence of a cline between regions due to a variation in the distribution of energy dedicated to growth and reproductive investment; which may affect the productivity of both populations.