Stock status assessment of frequently caught grunts, seabreams and snappers along the Kenyan coast

Small-scale fisheries along the Kenyan coast have a significant impact on the local economy, enhancing livelihoods and providing nutrition for coastal communities. Grunts, seabreams, and snappers account for a considerable catch of small-scale fisheries. Despite their importance, their fisheries are less prioritised within the regulatory framework due to limited information on their stocks. This study aims to provide baseline information on the stock status of four frequently caught species: Plectorhinchus gaterinus, Polysteganus coeruleoupunctatus, Pristopomoides filamentosus, and Lutjanus lutjanus, using Catch Assessment Survey (CAS) data from KMFRI collected from 2017 and 2023. Species composition and abundance of the fishers’ catch, species diversity, and gear usage were analysed. Length frequency and length-weight relationship of the frequently occurring species were assessed. Growth parameters, such as K (growth coefficient) and L (length infinity), as well as mortality, were estimated using electronic frequency analysis. Length-based spawning potential ratio and length-based indicators were used to assess stock status, using the estimated growth parameters K, L, mortality, and LWR as inputs. From the whole data set, a total of 1008 species belonging to 146 families were recorded: with a species Shannon diversity index (H’) of 4.58 and Pilou’s evenness (J) of 0.67. A total of 27 gears were found to target grunts, seabreams, and snappers. Small-sized fish (< 10 cm) were fished using ring nets, basket traps, handlines, monofilament gillnets, reef seine, and beach seine gears. Exploitation rates of Plectorhinchus gaterinus, Pristipomoides filamentosus, and L. lutjanus were above the threshold (E > 0.5), while P. coeruleopunctatus seemed to be underexploited (E < 0.5). The LBSPR results produced a Spawning potential ratio (SPR) for Plectorhinchus gaterinus (6 %), Pristipomoides filamentosus (17 %), and L. lutjanus (8 %), which were below the lower limit (SPR < 20), unsustainable threshold indicating growth and recruitment overfishing, whereas P. coeruleopunctatus maintains a healthy stock with a SPR of 54 %. LBI assessment indicated that stocks of Plectorhinchus gaterinus, Pristipomoides filamentosus, and Lutjanus lutjanus were in poor condition with signs of over-exploitation in most indicator ratios. In contrast, P. coeruleopunctatus exhibited a moderately healthy status. The findings of this study recommend a need for management strategies, including gear regulation, protection of spawning areas, and seasonal closures to enhance the sustainability of these critical fisheries.