Research Article: Growth, mortality, and exploitation rate of blue swimming crab (Portunus pelagicus Linnaeus, ۱۷۵۸) in Jepara Regency, Central Java, Indonesia

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 ۲۰۲۲ and February to August ۲۰۲۳. 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 = ۰.۰۰۰۰۵۳ × CW۳.۰۵. The carapace width at first capture (CWc) was estimated to be ۱۱۰.۵ mm. Peak recruitment occurred in August–September. The infinite carapace width (CW∞) was estimated at ۱۸۹ mm, with a growth curve index of ۱.۶. The crab followed the von Bertalanffy growth function (VBGF) of CWt=۱۸۹ (۱-e (-۱.۶(t + ۰.۰۵۸۴)). The total mortality was estimated at ۴.۴۶ yr-۱, fishing mortality at ۳.۰۳ yr-۱, and natural mortality at ۱.۴۳ yr-۱. The exploitation rate (E) was ۰.۶۸. This indicates that the rate of exploitation of P. pelagicus has exceeded the maximum sustainable yield (E=۰.۵) and is overexploited.

Keywords:

Carapace , Exploitation , Growth , Mortality , Recruitment