FISHERIES MANAGEMENT OF SAROTHERODON GALILAEUS (CICHLIDAE) AT WADI EL-RAIYANlAKES

FISHERIES MANAGEMENT OF SAROTHERODON GALILAEUS
(CICHLIDAE) AT WADI EL-RAIYANlAKES
BY
FAHMYL EL- GAMMAL AND SAHAR F. MEHAJ.VNA
National Institute ofOceanograp}ry andFisheriesP. O. Box, 182, Suez, Egypt.

E-Mail: [email protected]

ABSTRACT
A study ofthe age and growth ofSarotherodon galilaeus collectedfrom the
Wadi EI- Raiyan lakes was carried out by examining~the growth increment in
their otoliths. The maximum life span of S:.. galilaeus was found to be seven
years in the first lake and three years in the second one. The growth
parameters according to the von Bertalanffy growth model were estimated as
K=0.29 and Lc;a = 46.64 cm in the first lake and K=0.53 and La; = 27.89 cm in
the second one. The total mortality coeffiCient “Z” was found to be 0.8 year-] in
the first lake and 1.39 year-] in the second one. Natural mortality coeffiCient
“M” was estimated as 0.13 year-] in the first lake and 0.22 year-] in the second
one. Exploitation rate “E” was computed as 0.84 in both lakes. The relative
yield per recruit and relative biomass per recruit analysis showed that the
stock ofS. galilaeus in Wadi EI- Raiyan lakes is overexploited and the present
level ofexploitation rate should be reduced by about 25% in the first lake and
20% in the second lake to obtain the maximum relative yieldper recruit.