Biological parameters, resource exploitation, and utilization assessment of <i>Portunus trituberculatus</i> Miers, 1876 (Decapoda: Brachyura: Portunidae) protected from fishing in the Yangtze River Estuary, China

Abstract Portunus trituberculatus Miers, 1876 is a vital fishery resource in the Yangtze River Estuary and in coastal waters of China. We investigated its biological parameters and the status of its resource utilization following the fishing ban in the estuary in 2020. We analyzed growth and mortality parameters based on data from six cruises conducted between May 2022 and November 2023 using FiSAT II software. A total of 466 specimens were collected, revealing a male-to-female ratio of 0.68. Carapace widths ranged 17–175 mm for females, 18–174 mm for males. Estimated growth parameters included L∞ = 183.75 mm, Wt = 215.25 g, k = 1.2, and t0 = 0.127. Total mortality coefficients (Z) were 2.60 for females and 2.64 for males, while natural mortality (M) was 1.05. Fishing mortality coefficients (F) were 1.55 for females and 1.59 for males, with exploitation rates (E) of 0.596 and 0.602, respectively. While the male-to-female ratio and growth conditions are normal, resource utilization exceeds sustainable levels, indicating light exploitation. Continuous protection of P. trituberculatus stock and local crab resources in the Yangtze River estuary is recommended to ensure sustainable fisheries management.