GROWTH, MORTALITY AND FECUNDITY IN SUCCESSIVE GENERATIONS OF HELIX ASPERSA 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 snails Helix aspersa to be cultured indoors successfully in successive generations (originating from the crossing of snails coming from different clutches of a previous generation), and the effect of crowding on growth and reproduction in fast-, medium-, and slow-growing snails coming from the same clutches. The time needed for the snails to reach marketable size (25-32mm) varied from 2.5 to 5 months up to the 7th generation. The time needed for the snails to mature and reproduce from 4 to 7 months until the fifth generation. After the F5 x F5 generation, the final size of the snails decreased. The number of eggs did not differ statistically among the different generations but the reproductive success (how many snails reproduced/cage) increased from Fl = Fl generation onwards to F5 x F5. In F6 X F6 only three (out of 26) snails reproduced and in F7 x F7 none, although the snails remained under controlled conditions for 15 more months. Mortality in the different generations varied from 0-10% up to F5 X F5 but from F6 X F6 onwards increased and reached 25%. Concerning the origin of snails, it was found that larger snails (originating from Kyparissia, Peloponnesos) lay statistically more 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.