ILMU KELAUTAN: Indonesian Journal of Marine Sciences
Vol 31, No 3 (2026): Ilmu Kelautan

Length-based population dynamics of the horseshoe crab Tachypleus gigas and management implications for shrimp fisheries in Kotabaru Waters, South Kalimantan, Indonesia

Ledhyane Ika Harlyan (Fisheries Resource Utilization Study Program, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya)
Yogho Faiz Riadha (Fisheries Resource Utilization Study Program, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya)
Muhammad Arif Rahman (Fisheries Resource Utilization Study Program, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya)
Alvina Maharani (Fisheries Resource Utilization Study Program, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya)
Feni Iranawati (Marine Science Study Program, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya)
Wahida Kartika Sari (Fisheries Resource Utilization Study Program, Faculty of Fisheries and Marine Sciences, Universitas Brawijaya)
Prawira Atmaja Tampubolon (Research Center of Fishery, National Research and Innovation Agency)



Article Info

Publish Date
10 Sep 2026

Abstract

Shrimp fisheries in Kotabaru, South Kalimantan, represent an integral part of Indonesia’s small-scale coastal fishing sector, primarily operating with trammel nets. While targeting penaeid shrimp, these fisheries frequently capture non-target species such as the horseshoe crab (Tachypleus gigas), resulting in incidental bycatch. Despite their ecological significance, localized management frameworks and monitoring efforts for T. gigas populations remain insufficient, particularly in data-limited fisheries. This study assessed the stock status of T. gigas in Kotabaru waters using a length-based approach. A total of 234 individuals, representing the size fraction vulnerable to trammel nets, were sampled between December 2024 and March 2025, of which 105 females were used for gonad maturity analysis. Key biological parameters were estimated, including the length–weight relationship, length at first maturity ( cm), and length at first capture ( cm, to support a length-based spawning potential ratio (LB-SPR) analysis. Results showed that T. gigas exhibits negative allometric growth ( ), indicating faster increase in length relative to weight. The estimated Lc was below the L50, indicating that the catch is dominated by immature individuals. The LB-SPR model estimated a spawning potential ratio (SPR) of 14%, falling below the 20% limit reference point, which indicates recruitment overfishing. These findings highlight the vulnerability of horseshoe crabs to bycatch pressure and underline the need for improved fisheries management. Recommended measures include enhancing gear selectivity, implementing seasonal closures during spawning periods, and strengthening bycatch monitoring to support sustainable shrimp fisheries in Kotabaru waters. This study demonstrates the utility of the LB-SPR framework for assessing non-target bycatch species in data-limited conditions, providing a baseline for localized conservation strategies.

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Journal Info

Abbrev

ijms

Publisher

Subject

Earth & Planetary Sciences

Description

ILMU KELAUTAN: Indonesian Journal of Marine Sciences (IJMS) is dedicated to published highest quality of research papers and review on all aspects of marine biology, marine conservation, marine culture, marine geology and ...