Growth, mortality, and exploitation rate of blue swimming crab (Portunus pelagicus Linnaeus, 1758) in Jepara Regency, Central Java, Indonesia

Authors

1 Department of Aquatic Resource, Faculty of Fisheries and Marine Science, Universitas Diponegoro, Tembalang, Semarang, Postcode: 50275

2 Department of Marine Science, Faculty of Fisheries and Marine Science, Universitas Diponegoro, Tembalang, Semarang, Postcode: 50275

10.22092/ijfs.2024.131965

Abstract

Regarding the exploitation of blue swimming crab (Portunus pelagicus) resources in the Java Sea in the last decade, it is presumed to be overfished. This study aims to analyze population dynamics by examining the relationship between carapace width and weight, recruitment patterns, the carapace width at first capture (CWc), growth parameters, mortality rate, and the exploitation level of P. pelagicus. The study was conducted in the north coastal waters of Jepara Regency, Indonesia, from May to September 2022 and February to August 2023. A survey method and direct observations were used to sample the catch area. The growth and mortality rate parameters were estimated from carapace width frequency data and analyzed using ELEFAN I software in the FiSAT II program package. The results showed that the relationship between carapace width and weight was positively allometric, following the equation W = 0.000053 × CW3.05. The carapace width at first capture (CWc) was estimated to be 110.5 mm. Peak recruitment occurred in August–September. The infinite carapace width (CW∞) was estimated at 189 mm, with a growth curve index of 1.6. The crab followed the von Bertalanffy growth function (VBGF) of CWt=189 (1-e (-1.6(t + 0.0584)). The total mortality was estimated at 4.46 yr-1, fishing mortality at 3.03 yr-1, and natural mortality at 1.43 yr-1. The exploitation rate (E) was 0.68. This indicates that the rate of exploitation of P. pelagicus has exceeded the maximum sustainable yield (E=0.5) and is overexploited.

Keywords

Iranian Journal of Fisheries Sciences
Volume 23, Issue 6
November 2024
Pages 971-983

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