Intra and inter-specific mating options for gynogenetic reproduction of Carassius gibelio (Bloch, 1783) in Lake Pamvotis (NW Greece)

Gibel carp Carassius gibelio exhibits gynogenctic reproduction by utilising the sperm of other species. Over a period of twelve months, the spawning behaviour of gibel carp in Lake Pamvotis (NW Greece) was monitored. Females almost exclusively (97.7\%) composed the population, indicating gynogenesis using the sperm of other species. Reproduction began in March and lasted through April. Contrary to the situation reported in other ecosystems, common carp was not present in the spawning grounds during the spawning season of gibel carp; the most abundant other species present at that time was Rutilus ylikiensis. To evaluate the sperm donating results of R. ylikiensis as compared with other species of the lake, eggs of gibel carp were fertilised with sperm of R. ylikiensis (group 1), Carassius auratus (group 2), and Cyprinus carpio (group 3). Also, gibel carp eggs attached to natural substrates were collected from the spawning grounds (group 4). Hatching success ranged from 9-29\% in group 4, compared to 95-98\% in groups 1, 2 and 3. Over a period of 60 days after hatching, mortality ranged from 35\% (group 1) to 56\% (group 3), and specific growth rate from 2.4\% (group 3) to 2.9\% (group 1). We conclude that gibel carp can successfully utilise sperm of ylikiensis roach, which was the best available sperm donor option for the gynogenctically reproducing gibel carp of the take.