GROWTH, MORTALITY AND FECUNDITY IN SUCCESSIVE GENERATIONS OF HEIX ASERSA MULLER CULTURED INDOORS AND CROWDING EFFECTS ON FAST-, MEDIUM- AND SLOW-GROWING SNAILS OF THE SAME CLUTCH

This paper examines the optimum conditions for edible snailsHelix aspersa to be cultured indoors successfully in successivegenerations (originating from the crossing of snails comingfrom different clutches of a previous generation), and the effectof crowding on growth and reproduction in fast-, medium-, andslow-growing snails coming from the same clutches. The timeneeded for the snails to reach marketable size (25–32mm)varied from 2.5 to 5 months up to the 7th generation. The timeneeded for the snails to mature and reproduce from 4 to 7 monthsuntil the fifth generation. After the F5 x F5 generation, thefinal size of the snails decreased. The number of eggs did notdiffer statistically among the different generations but thereproductive success (how many snails reproduced/cage) increasedfrom Fl = Fl generation onwards to F5 x F5. In F6 x F6 onlythree (out of 26) snails reproduced and in F7 x F7 none, althoughthe snails remained under controlled conditions for 15 moremonths. Mortality in the different generations varied from 0–10%up to F5 x F5 but from F6 x F6 onwards increased and reached25%. Concerning the origin of snails, it was found that largersnails (originating from Kyparissia, Peloponnesos) lay statisticallymore eggs (138.40 ± 29.60, N =5) than smaller ones (77.38± 40.42, N=4) (originating from Hania, island of Crete).Hatching success was greater, too. (Received 10 September 1996; accepted 24 March 1997)