POPULATION DYNAMICS OF Tilapia zillii (Gerv.) IN LAKE QARUN, EGYPT

POPULATION DYNAMICS OF Tilapia zillii (Gerv.)
IN LAKE QARUN, EGYPT
By
S. N. FALTAS*
National Institute of Oceanography and Fisheries, Alexandria, Egypt.
Key words: Tilapia zillii, Mortality, Yield per recruit.
ABSTRACT
Population dynamics of Tilapia zillii (Gerv.) in Lake Qarun was
studied in the present work. Samples were taken from the trammel catch
during !991 . Estimation ofmortality coefficients and yield per recruit
are based upon age composition and growth parameters. Total
mortality, natural mortality andfishing mortality were 2.645, 0.908 and 1.737 respectively. Reducing the value ofthe presentfishing mortality
(Fishing effort) by 60% causes only a decrease of10% in the yield in
weight per recruit . The results proved that the trammel fishery ofT.
zillii was over-exploited in Lake Qarun .