Critical Exploitation Status of the Mitre Squid, Uroteuthis chinensis, in the Karimata Strait Driven by an Extreme Size-at-Maturity to Size-at-Capture Discrepancy

The mitre squid, Uroteuthis chinensis, is a commercially vital cephalopod in Southeast Asia, yet population-specific data essential for sustainable management are often lacking for key fishing grounds. This study provides the first comprehensive assessment of the reproductive biology and exploitation status of U. chinensis in the heavily fished Karimata Strait, Indonesia. A total of 1,329 specimens were collected monthly from April 2023 to March 2024 and were analyzed for sex ratio, gonad maturity, length at first maturity (Lm₅₀​), and length at first capture (Lc₅₀​). The results revealed a unique population structure, characterized by a persistent male-biased sex ratio (1.63:1; 62% males) and an exceptionally large size at maturity (Lm₅₀​ = 28.9 cm mantle length), nearly double that reported from adjacent regions. Crucially, the mean length at first capture (Lc₅₀) was only 18.1cm. The condition where Lc₅₀​ is significantly smaller than L_m50​ provides unequivocal evidence of severe growth overfishing, indicating that the fishery predominantly harvests immature individuals before they can contribute to the spawning stock. These findings underscore the precarious status of the stock and highlight an urgent need for immediate management interventions, such as implementing a minimum legal size and gear modifications, to ensure the long-term sustainability of this critical fishery.