Zoology
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/3752
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Item Morphological and histological changes in the gonads of the estuarine cichlid fish Etroplussuratensis (Bloch) during gonadal development(Bulletin of the National Institute of Oceanography, 1984) Pathiratne, A.; Costa, H.H.Item The Effects of leaving central bare areas in traditional circular brush-parks on the yield of fish in the brush-park fishery in Negombo estuary, Sri Lanka.(Japan International Marine Science and Technology Federation, 1995) Costa, H.H.; Wijeyaratne, M.J.S.Item Impact of Oreochromis mossambicus ? O. niloticus (Pisces: Cichlidae) hybridization on population reproductive potential and long-term influence on a reservoir fishery(Fisheries Management and Ecology, 1996) Amarasinghe, U.S.; de Silva, S.S.Exotic cichlids, introduced to Asia during the second half of the twentieth century, contribute significantly to the reservoir fisheries in the region. The two major cichlid species, Oreochromis mossambicus (Peters) and O. niloticus (L.), tend to interbreed easily. In Sri Lankan reservoirs, introgressive hybridization of these two cichlids takes place. The reproductive biology of O. mossambicus, O. niloticus and their hybrids in three reservoirs in Sri Lanka was evaluated. An imbalance in sex ratio with male dominance was evident. The estimated fecundity for 20-cm fish, using fecundity-total length relationships for various populations, indicated that there was a decline in fecundity in hybrid forms. It is hypothesized that the long-term effect of crosshybridization between the two cichlids might lead to a decline in fish yields in perennial reservoirs of Sri Lanka. The importance of the findings of the present study for the management of the reservoir fisheries in Asia is highlighted.