FISH STOCK ASSESSMENT SURVEY IN MANZALA, EGYPT

FISH STOCK ASSESSMENT SURVEY IN MANZALA, EGYPT
MOUNJR M. ISIII\I<*, MI\GDY T. IOIALJL** AND D.n. TOEWS*** National Institute of oceanography and Fisheries, Cairo. Dept. of Zoology. Faculty of Science, Ain-Shams University. Fisheries Branch, Dept. of Natural Resources, Winnipeg. Mani1oba, Canada. ABSTRACT Total standing fish stocks (biomass) of Lake Manza1a are estimated at 60,000 t, of which 85 or 51,000 tare ti1apia species. In general, standing stocks range from 2,470 Kg/hectare in the southern region to 62 Kg/hectare in -I. the northern region, corresponding well with catches on a regional basis. Exploitation rates increase exponentially with standing stock, from 0.2 to 0.3 in low stock areas to over 1.0 in regions having the highest standing stocks. Insplte of the intensive fishing pressure and very high y1elds and turnover rates 1n the southern region, there are some signs that the fishery is still under exploitation.