Zoology
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/3752
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Item Studies on the biology of young grey mullet, Mugil cephalus L.(FAO of United Nations, Rome, Italy, 1976) de Silva, S.S.; Wijeyaratne, M.J.S.Item Some Chemical Characteristics of Fresh and Salt-Dried Tilapia mossambica Peters(National Science Council of Sri Lanka, 1979) de Silva, S.S.; Rangoda, M.Item Studies on the fish ponds at Pitipana, Negombo 1. Seasonal and diurnal variation of some hydrobiological factors(The Fisheries Research Station, 1979) de Silva, S.S.; Silva, E.I.L.Item Fish Fauna of a coastal lagoon in Sri Lanka: Distribution and seasonal variation(The Fisheries Research Station, 1979) de Silva, S.S.; Silva, E.I.L.Item Some Chemical Characteristics of Fresh and Salt-Dried Tilapia mossambica Peters(Journal of National Science Council, Sri Lanka, 1979) de Silva, S.S.; Rangoda, M.Item Spatial Changes in Growth and Mortality and Effects on the Fishery of Oreochromis mossambicus (Pisces, Cichlidae) in a Man-made Lake in Sri Lanka(Asian Fisheries Society, 1989) Amarasinghe, U.S.; de Silva, S.S.; Moreau, J.Growth and mortality were estimated from the length-frequency data of Oreochromis mossambicus from the gillnet fishery of Parakrama Samudra, a man-made lake in Sri Lanka, separately for its three basins. The asymptotic length (L?) and the growth constant (K) of O. mossambicus in the northern basin of the lake (34.9 cm and 0.3, respectively) are appreciably different from those in other tow basins (middle basin, L? = 38.8 cm and K = 0.24; southern basins are 2.22, 1.64 and 1.07, respectively. The spatial differences in growth are suggested to be due to different fishing pressure and environmental conditions. Yield-per-recruit analysis indicate that in the populations with low L? and high K, exploitation level should be maintained at a low level. Fish yield could be optimized by increasing the size of first capture and exploitation rate in the population with high L? and low K.Item Studies on the biology of young grey mullet, Mugil cephalus L. II. Food and Feeding(Science Direct, 1977) Wijeyaratne, M.J.S.; de Silva, S.S.Item A comparative study of the food and feeding habits of Puntius Bimaculatus and P.Titteya (Pisces, Cyprinidae)(brillonline.com, 1976) de Silva, S.S.; Kortmulder, K.; Wijeyaratne, M.J.S.Item Stunting in Oreochromis mossambicus (Peters) (Pisces, Cichlidae): An evaluation of past and recent data from Sri Lankan reservoir populations(Journal of Applied Ichthyology, 1989) de Silva, S.S.; Amarasinghe, U.S.Tilapiine fish are known to become stunted under different environmental conditions. Of the tilapia, Oreochromis mossambicus (Peters), once considered to be the aquatic chicken, is now treated as a nuisance species in some countries because of its tendency to stunt easily. O. mossambicus is the mainstay of the commercial gillnet fishery in existence in the multitude of reservoirs in Sri Lanka for over 35 years. Published and new evidence on O. mossambicus population traits are presented with a view to evaluating whether the populations in Sri Lankan reservoirs are stunted or not. The main lines of evidence considered are the mean size at maturity (Lm), the proportion of individuals below 20 cm total length in the commercial landings, and growth performance of the individual reservoir populations. Statistically valid inter-relationships exist between the mean length at maturity and the proportion of undersized individuals (below 20 cm) in the landings, and the ratio of the reservoir catchment or watershed area to surface area. Evidence on Lm indicate that there is a tendency for O. mossambicus populations to stunt, however, evidence on growth and mean landing size do not indicate stunting.