Weight performance index value (Ø) was 1.87. Length performanceindex (21) value was 2.73. The length attained at infinity (L4) was 13.2 cm. The Maximum length at age attained Lmax was 12.5 cm weighing99.9 g. Growth increment in length (6.7 cm) was highest in 1-2 years while grow th inweight was highest (74.1g yrG1) in 2-3 years. The largest specimen measured 13.1 cm andweighed 99.6 g at age 3+. The regression equation for length breadth relationship was LogM = 1.50LogTL and correlation coefficient was 0.994 at p<0.05. The regression equation for the length weight relationship was Log W = 0.00001+3.23logL andcorrelation coefficient was 0.951 at p<0.05. Morphometric parameters of Parailia pellucida from the fresh Water reaches of lower Nun Riverin the Niger Delta area of Nigeria, was studied for a period of one year (Jan.-Dec. These changes in the lake’s food web require modifications in the management of the lake and its fisheries. As a result of the dietary changes, both species have had to compete with other fish species for the limited zooplankton resources present in the lake, as well as contending with Cyanobacterial blooms. molitrix now preying almost exclusively on zooplankton. Results showed that a major dietary shift from herbivory to omnivory has occurred since the 1970s in both S. The contents of their stomachs were identified and analyzed. molitrix individuals were randomly collected over a five-year period from various places and times in Lake Kinneret. To examine the food habits of the two fish species following the changes in the lake, a total of 300 S. Sarotherodon galilaeus has adapted to the ecosystem changes and the scarcity of its primary food source, affecting interactions with other fish in the lake, such as the stocked silver carp, Hypophthalmichthys molitrix. The Saint Peter’s fish, Sarotherodon galilaeus, the most valuable commercial fish in the lake, was a prime consumer of P. The Lake Kinneret (Sea of Galilee) ecosystem has undergone physical and biological changes over the past 25 years, including a shift from a dinoflagellate Peridinium gatunense)-dominated system to one in which Cyanobacteria play a major role. It is surmised that recruitment of stocked fish could be increased by introduction in December and by use of fingerlings which are potentially able to grow to marketable size in less than two seasons. galilaea became lean, especially the age-0 group. During the autumn months, there was hardly any length increment, and all T. However, only a small proportion of age-1 fish reached marketable size by July, when their food supply began to diminish. Recruitment to the fishery, at 17–20cm, occurred between ages l+and3+.The highest growth rates for age-1 T, galilaea, 1–2% mean weight per day, occurred in April and May, the Peridinium season. Yearly fluctuations in size distribution were attributed to changes in the proportions of fast- and slow-growers, as well as in the abundance of year-classes. First year's growth, 23–152mm, was closely related to final length, which appeared to be affected by genetic variation in the population. Three broods hatched in years of relatively high water levels (1970, 19) yielded especially low recruitment.The Von Bertalanffy growth coefficient (K) was estimated at 0.67, and final length (L∞) at 25–36cm total length. Assuming a natural mortality (M) of 0.94, total stock size averaged 300–700 tonnes in that period, while recruitment averaged < 0.7–3 million per year. Total yearly mortality (Z) was estimated at 1.84 between 19. Between 19, catches of Tilapia galilaea in Lake Kinneret fell from an annual average of about 200 tonnes to a low of 70 tonnes in 1974, and then returned to their former level.
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