A comprehensive understanding of the commercially valuable European lobster,
Homarus gammarus's population biology is essential for the long-term management of its fishery. It would also determine the impact of cultured animals on wild populations as the concepts of lobster population enhancement by rearing juveniles through highly vulnerable larval stages prior to release and lobster ranching have become popular.
The ability of three methodologies, morphometrics, allozymes and RAPDs to
detect potential population structuring was evaluated. Measurement of 15 morphometric characters subjected to PCA successfully separated the two species, H. gammarus and H. americanus but failed to separate H. gammarus from 10 locations.
H. gammarus from 10 locations screened at 4 polymorphic loci revealed no
significant genetic differences between locations (overall F_ST = 0.003). Exact probability tests showed 7 departures from Hardy-Weinberg expectations, all due to heterozygote deficiency. Dendrogran1s of Nei's (1978) unbiased distance (D) and Reynolds et al.'s coancestry distance (D) showed lobsters from Johnshaven and Uist clustering together while the remaining populations are almost genetically identical.
The RAPD method, using 4 primers to produce 59 polymorphic bands successfully detected population structuring in H. gammarus (mean F_ST for all loci = 0.2906). Estimated number of migrants (Nm = 0.6) was low. Dendrograms of Nei's (1978) unbiased distance (D) and Reynolds et al. 's coancestry distance (D) showed lobsters from Johnshaven and Uist clustering together. A Mantel correlation test between Nei's (1978) unbiased genetic distance and geographic distance indicated a positive though not significant correlation (r = 0.049)