Population structure, stock assessment, and fisheries management of blue swimming crab Portunus pelagicus, Linnaeus 1758, in the eastern Mediterranean Sea

Al-Beak, Ahmed; Ahmed, Mohamed; Hany, Abedel-Rahman; Mohamed, Zakaria; Zekry, Saeed

doi:10.21608/maj.2023.334692

Population structure, stock assessment, and fisheries management of blue swimming crab Portunus pelagicus, Linnaeus 1758, in the eastern Mediterranean Sea

Document Type : Original Article

Authors

¹ Marine Fisheries Department, Faculty of Aquaculture and Marine Fisheries, Arish University, Egypt.

² Marine Fisheries Department, Faculty of Aquaculture and Marine Fisheries, Arish University, Egypt

10.21608/maj.2023.334692

Abstract

Although there are many fisheries studies on Egyptian western Mediterranean Sea coasts, a few of them concern with Egyptian eastern Mediterranean Sea fisheries. During this study, 924 specimens of blue swimming crab caught along the eastern Mediterranean Sea during fishing season 2022/2023 for management of Portunus pelagicus fisheries. Minimum and maximum carapace widths was 5.5 – 13.5 cm for males and 6.4 – 13.2 cm for females. Estimated Von Bertalanffy growth parameters were L∞= 17.82 cm; K= 0.15 y-1; t0= - 1.28 yr-1 for males, L∞= 17.41 cm; K= 0.15 yr-1; t0= - 1.41 yr-1 for females, and L∞= 17.68 cm; K= 0.17 yr-1; t0= - 1.19 yr-1 for combined sexes. Estimation of the yield per recruit on the region, shows the crab stock is being exploited beyond its maximum biological limit, but the increasing of fishing mortality to the level which gives the maximum Y/R need to increase the fishing with 824% of its current value, will cause an insignificant increase in Y/R by 15% and a considerable decrease in biomass per recruit and reach only 4% from the virgin stock. That indicates the P. pelagicus population is overfished in the eastern Mediterranean Sea fisheries. Accordingly, the recommended procedure for reduction of fishing efforts or changing the mesh sizes of bottom trawl gear must apply.

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