TERRITORIALITY, EGG DESERTION AND MATING SUCCESS OF A PATERNAL CARE FISH, HYPOPTYCHUS DYBOWSKII (GASTEROSTEIFORMES)

The territoriality of parental males and the hatching rate of egg masses in their territories were examined in Hypoptychus dybowskii, a species in which territorial males care for egg masses only just after mating, and sneaker males are known to occur. Most males deserted the territories with egg masses, but the hatching rates of abandoned and attended egg masses were similar. A large percentage of the deserted territories with egg masses were taken over by non-territorial males. Comparison of the mating success between males that deserted territories and those that attended territories showed that territory desertion occurred when males experienced fewer chances to mate. These results indicate that territorial males contributed little to embryonic survivorship after egg mass hardening, and deserted their territories depending on the mating rate. Such an unique reproductive strategy may be adaptive when there are no parental costs after arrangement of egg masses, high hatching rates of abandoned egg masses, and a high chance of sneaking.