PROLIFERATED POPULATION DENSITY AND ITS IMPACT ON AGE STRUCTURE AND GROWTH OF TILAPIA (OREOCHROMIS MOSSAMBICUS, P. 1852) IN JAISAMAND LAKE (RAJASTHAN), INDIA.

Age, growth and production performance of O. mossambicus (Peters, 1852) in relation to proliferation of population density in Jaisamand Lake, Udaipur (Rajasthan) has been described and analyzed in the present paper. In this study, the production data for fishing year 1995-96 (February 1995 to March 1996) and 2012-13 (February 2012 to March 2013) are compiled and simultaneously fish morphological data (length and weight) and scale samples are used for age and growth analysis. The findings show that contribution of Tilapia in the total fish production of Jaisamand hiked by 54% to 85% from 1995-96 to 2012-13 which conforms to the predicted invasive effect on other fish fauna and ecosystem of Jaisamand Lake. This increasing trend of Tilapia population is not only affected the indigenous fish population but age and growth structure of Tilapia also has been found affected. Age structure was composed of 3+ year classes during 1995-96. However, due to population density pressure dwarfism was noted and it increased to 4+ year classes. The growth in terms of length and weight also reduced and in AG 1+ 44.21% and 9.09%, in AG 2+ 62.86% and 24.64%, in AG 3+ 72.69% and 38.83% and in pooled population 72.70% and 47.66%, respectively exhibiting a clear decline. On the basis of these findings it can concluded that population increased density and consequent pressure adversely affected indigenous fish fauna resulting into reduced growth rate which directly or indirectly effects livelihood of fisherman and economics of state. [ABSTRACT FROM AUTHOR]