LENGTH-WEIGHT RELATIONSHIP, SEX RATIO AND CONDITION FACTOR OF BLUE SWIMMER CRAB (Portunus pelagicus) IN BARDAWIL LAGOON, EGYPT

ElSaid, Merihan Hossam; Hassanen, Gaber D.I.; Abd Elnabi, Heba ElSayed; Omar, Attia Ali

doi:10.21608/sinjas.2022.147098.1121

LENGTH-WEIGHT RELATIONSHIP, SEX RATIO AND CONDITION FACTOR OF BLUE SWIMMER CRAB (Portunus pelagicus) IN BARDAWIL LAGOON, EGYPT

Document Type : Researches

Authors

¹ Dept. Fisheries and Aquaculture, Fac. Environ. Agric. Sci., Arish Univ., Egypt.

² Dept. Fish Resou. and Aquac., Fac. Environ. Agric. Sci., Arish Univ., Egypt.

³ Dept. Fish Res. and Aquacul., Fac. Environ. Agric. Sci., Arish Univ., Egypt.

⁴ National Inst. Oceanography and Fisheries, Egypt.

10.21608/sinjas.2022.147098.1121

Abstract

More than 1085 ton from blue swimmer crab (BSC) annually captured from the fisheries of the Bardawil Lagoon waters. since the last 30 years, an increasing has been witnessed in the production of this species (the production recorded 2100 ton in 2009). For management purposes, information about the fishery's biology and population structure is required. Hence, monthly samples of P. pelagicus were collected from the commercial catch of Tlul Bardawil Lagoon, Egypt during the period from May to December 2021. A number of 6441 specimens were measured for morphometric relationships, sex ratio, age determination using carapace width frequency, population structure, mortality rate and exploitation ratio. The study revealed that P. pelagicus was targeted by trawl net (kalca) small bottom trawler as a by-catch and trammel nets. Carapace width- total weight relationship showed positive allometric growth (b-value= 3.1866). Higher condition factor was observed in the Carapace width 8 cm. Four age groups were determined and age group +II was dominant by number (55.0%). Parameters of the von Bertalanffy equation were 16.28 cm, 1.4 year^-1, and -0.0988 year^-1 for CW∞, K and to, respectively. The carapace width at first capture was estimated (CW50 = 9.5 mm). The mortality rates were calculated as 7.91, 2.45 and 5.46 year-1 for total, natural and fishing mortalities, respectively. The blue swimmer crab fisheries on the Bardawil Lagoon is over-exploited (E= 0.69). Some management measures were suggested to maintain its stock for sustainability.

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