A study on the biology, population parameters and stock assessment of the pharaoh cuttlefish Sepia pharaonis Ehrenberg, 1831 was carried out from the Arabian Sea off Oman during 2001-2002. The mantle length - total weight relationship for...
moreA study on the biology, population parameters and stock assessment of the pharaoh cuttlefish Sepia pharaonis Ehrenberg,
1831 was carried out from the Arabian Sea off Oman during 2001-2002. The mantle length - total weight relationship for
pooled sexes was 0.4067ML2.5164. The population of S. pharaonis spawned between August and December as well as
during April and May. The monthly gonado-somatic indices (GSI) and relative condition factor (Kn) in males and females
were high during spawning months. Males were dominant over females (M:F=1:0.87) in commercial landings. The length
at first maturity for males was 19.0 cm of mantle length and females matured at 20.2 cm.
The estimated von-Bertalanffy growth parameters were:
L∞= 46.5 cm; K = 1.04 y-1 and t0 = -0.13. The total mortality (Z), natural mortality (M) and fishing mortality (F) coefficients were 2.0 y-1, 1.52 y-1 and 0.48 y-1 respectively. The MSY calculated stood at 9,608 t. The exploitation rate (E) was 0.24. The Yw/R increased considerably up to F=1.8. The B/R at F=1.9 for
Lc 16 cm (0.27 kg) could be obtained at F=4 for an increased
Lc of 20.8 cm. The plot of relative yield indicated the stock to be nearly depleted at F = 3.0, when Lc was 16 cm. However, the stock would withstand an F up to 4 at the Lc of 20.8 cm. The current exploitation pattern indicates scope for further expansion of the fishery.
Keywords: Arabian Sea, Growth, Mortality, MSY, Oman, Spawning, Sepia pharaonis
