Fecundity of the European lobster (Homarus gammarus) off southwestern Norway after stock enhancement:: do cultured females produce as many eggs as wild females?

An enhancement project with European lobster (Homarus gammarus) began in 1990, and over the following 5 years some 128 000 hatchery-produced juveniles of average age about 9 months were released around the islands of Kvitsoy, southwestern Norway. Recaptures of reproductive female lobsters of cultured origin raised the question as to whether hatchery-reared females could perform as well as wild females in terms of egg production. A fecundity study therefore compared females of wild and cultured origin during autumn of 1996, and spring and autumn of 1997. No significant differences were found in size-specific fecundity (F = 0.0045 CL3.22; n = 215; r(2) = 0.88; CL is carapace length), weight of egg mass, embryonic development, or egg size (diameter or dry weight). Further, the number of eggs produced per female was in the same range as it was about 90 years ago, i.e. before the local stock collapsed. There were no indications of significant differences in fecundity between seasons and therefore no egg loss for the incubation period from October 1996 to the end of May 1997. The results suggest that more eggs are produced by the larger females than in lobsters elsewhere in Europe, but compare well with American lobsters (H. americanus) of the same size range and living in the same temperature regime (off Newfoundland).