Research Article

Towards sustainable management of the Cunene horse mackerel (Trachurus trecae) in Guinea-Bissau waters

¹ Department of Oceanography and Fisheries, Faculty of Sciences and Technology, University of the Azores, Horta, Azores, Portugal
² Instituto Nacional de Investigação das Pescas e Oceanografia - INIPO, Av. Amílcar Cabral, Rua 12 Bissau, CP 102 - Bissau, Guinea-Bissau
³ School of Aquatic and Fishery Sciences, University of Washington, Seattle, United States
⁴ University of the Azores, Institute of Marine Sciences - OKEANOS, Rua Professor Doutor Frederico Machado 4, 9900-140 Horta, Portugal
⁵ CIBIO, Research Centre in Biodiversity and Genetic Resources, InBio Associate Laboratory, BIOPOLIS Program in Genomics, Biodiversity and Land Planning; UNESCO Chair – Land Within Sea: Biodiversity & Sustainability in Atlantic Islands, University of the Azores, Rua da Mãe de Deus, 9500-321 Ponta Delgada, Portugal

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 13 December 2025
Accepted: 18 May 2026

Abstract

This study assessed the status of the Cunene horse mackerel (Trachurus trecae) stock in Guinea-Bissau (2018–2023) using fishery-dependent and independent data. Catches ranged from 29.1 kt (kilotones) in 2020 to 10.2 kt in 2023, dominated by Chinese (57.2%) and Guinean (22.6%) fleets. Fishing was concentrated between January and May, mainly in the 10–12°N and 16–18°W area, with demersal trawl accounting for 52.1% of catches. Biological parameters revealed negative allometry with b = 2.80 [2.75–2.84], L₅₀ = 20.0 [19.6–20.3] cm for grouped sexes, L_∞ of 48.8 [46.4–52.2] cm, K of 0.55 [0.34–0.74] yr⁻¹, and M of 0.67 [0.47–0.87] yr⁻¹, indicating a “fast” life history. Length-based indicators show reduced yields and loss of large spawners, suggesting current exploitation patterns might be unsustainable, but results were considerably sensitive to life history parameter values, particularly L_∞ and L₅₀, which warrants continued data collection. These findings call for immediate science-based management, which might include seasonal closures, reduced fishing effort, improved gear selectivity, and enhanced monitoring. Enhanced institutional capacity and regional cooperation are critical to strengthening monitoring efforts.