FEMALE PREFERENCE AND FILIAL CANNIBALISM IN AIDABLENNIUS SPHYNX (TELEOSTEI, BLENNIIDAE) - A COMBINED FIELD AND LABORATORY STUDY

In the fish Aidablennius sphynx, in which males continuously care for up to 7000 eggs throughout the breeding season, females prefer to mate with males that already guard eggs, The present study shows that this preference appears to be adaptive because the probability of eggs bei ng cannibalized decreased with brood size. In the field, on average 36 eggs disappeared from nests per day, where the main egg predator seem ed to be the guarding male. Experiments showed that males selectively consumed dead eggs, probably to prevent the spread of infections. Howe ver, only with large broods did the numbers of eggs cannibalized in th e field correspond to the egg mortality rate, that was determined to b e 0.8%. When guarding small broods, males have probably also eaten hea lthy eggs. Breeding males suffered an average weight loss of 19.4%, Th is suggests that breeding males are restricted in foraging opportuniti es. When a male was experimentally fed, he cannibalized fewer eggs onl y when guarding small broods, not when guarding large broods, Therefor e, it seems that caring males daily harvest eggs to remain in sufficie nt condition, In large broods they use eggs that recently died. When t he male is guarding small broods the low numbers of dead eggs do not s uffice, and healthy eggs are also eaten.