Growth and population dynamics of the cuttlefish Sepia savignyi Blainville in the Gulf of Suez, Red Sea

Abstract

Growth, mortality, recruitment and yield per recruit of the cuttlefish Sepia savignyi from the Gulf of Suez were examined during October 2002 - May 2004. Growth differed significantly between sexes where females grew faster and reached larger sizes than males. The theoretical maximum mantle length MLα, was estimated as 18.15 cm for males and 30.92 cm for females. The growth parameter K was 1.61 year-1 for males and 0.59 year-1 for females. Total, natural and fishing mortality coefficients were 4.15, 1.61 and 2.54 year-1 respectively for males and 1.78, 0.66 and 1.12 year-1 respectively for females. The exploitation ratio obtained (0.61 for males and 0.63 for females) suggested that the population of S. savignyi in the Gulf of Suez has been heavily exploited. Length at first maturity was estimated at 9.51 and 10.22 cm ML, while the length at first capture was estimated at 7.23 and 8.38 cm ML for males and females respectively. Yield per recruit and biomass per recruit analysis for sexes combined revealed that F should be reduced by about 44% to achieve the maximum Y/R. All approaches point to the need for drastic reduction in fishing pressure by about 40-50% of the present level in the Gulf of Suez.