Vulnerability of stocks of Leptoscarus vaigiensis and Octopus cyanea to artisanal fishing intensity along Kilifi Coastal Waters

Artisanal fisheries are central to sustaining coastal community livelihoods, yet their multispecies and multi-gear dynamics pose challenges for effective management and conservation. In the western Indian Ocean, two key resources - the marbled parrotfish (Leptoscarus vaigiensis) and the day octopus (Octopus cyanea) - are closely linked to seagrass and coral reef habitats, respectively. L. vaigiensis contributes ecologically by grazing on algae and maintaining reef health, while O. cyanea, a short-lived and fast-growing benthic invertebrate, exhibits rapid population fluctuations under environmental stress and fishing pressure. This study assessed seasonal productivity and resilience of these species to artisanal fishing intensity within a ~10 km² fishing ground in Kilifi coastal waters. Monthly fishing effort and yields were recorded between March 2025 and February 2026. Using the Schaefer Model with CPUE as a proxy for relative abundance, maximum sustainable yields, optimal fishing efforts, and gear-specific vulnerabilities were estimated. Results indicated depressed stock abundance between April and September, coinciding with southeast monsoon winds, a season characterised by rough waters and elevated ocean surface temperatures. L. vaigiensis was sustainably exploited below MSY using gillnets and handlines, whereas O. cyanea was overexploited particularly by arrows, but sustainably harvested with spearguns at an optimal effort of three fishers. Findings highlight the need for alternate use of arrows or spearguns - never both simultaneously - for octopus fisheries. Regulatory recommendations include limiting exploitation of L. vaigiensis to a maximum of five gillnet fishers and six handline fishers, and restricting O. cyanea harvest to three arrow or speargun fishers per 10 km². These measures would enhance ecological resilience and economic sustainability of artisanal fisheries in the region.