Developmental and ecological stages in the life history of milkfish Chanos chanos Forsskal

Seven stages in the life history of the milkfish C. chanos , are recognized and suggested: A, embryonic; B, yolksac larval; C, larval; D, postlarval; E, juvenile; F, subadult; G. adult. An outline is presented of the life history. It is concluded that the milkfish, throughout the known stages of their life history are well adapted and equipped for optimal survival. High swimming performance, broad flexibility in feeding habits, high adaptability to a wide range of physicochemical conditions of the environment are but a few of the adaptations. The main driving force in all developmental stages is the evolutionary response to food distribution and availability followed by predation pressure.

The natural life history of milkfish

Following brief descriptions of the various phases in the natural life history of the milkfish (Chanos chanos), namely adults, eggs and embryos, larvae, fry and metamorphosis, juveniles and sub-adults, a summary is provided of the life history, providing also a schematic diagram.

The history of fish communities, biodiversity and environment of Lake Victoria and the lessons learnt

The first fishery survey of Lake Victoria was conducted between 1927 and 1928 (Graham 1929). Atthat time, the lake had a diverse fish fauna and the fishery was dominated by two endemic tilapiine cichlids; Oreochromis esculentus (Graham 1929) and O. variabilis (Boulenger 1906). There were a number of other species such as Protopterus aethiopicus Heckel 1851, Bagrus docmac (Forsk.) 1775, Clarias gariepinus (Burchell), Barbus species, mormyrids, Synodontis spp, Schilbe intermedius (Linn.) 1762 and Rastrineobola argentea Pellegrin, 1904 that were also abundant in the lake most of which made a significant contribution to the fishery (Graham 1929, Worthington 1929, 1932, Kudhongania & Cordone 1974). Haplochromine cichlids were represented by at least 300 species more than 99% of them endemic (Greenwood, 1974; Witte et al., 1992 a & b). The fishery of Lake Victoria was similar to that of lakes Kyoga and Nabugabo (Worthington 1929; Trewavas 1933; Greenwood 1965, 1966; Beadle 1962, 1981). There were also important fisheries on the inflowing rivers of Lake Victoria, the most important of which were Labeo victorianus and Barbus altianalis (Cadwallader 1965). The small sized species notably Rastrineobola argentea and haplochromines cichlids were not originally commercially exploited.