CHARACTERIZATION OF FISHERY RESOURCES AND IMPACTS OF ARTISANAL FISHING ON SEAGRASS MEADOWS OF GAZI BAY, SOUTH COAST, KENYA

Abstract

isheries resources are critical to coastal communities livelihoods, providing food and income. The exploitation of fisheries resources in the tropics is mainly small-scale in nature characterized by being multi-species and multi-gear and conducted over the entire seascapes, from mangroves, seagrass meadows to coral reefs using low technology crafts such as dug-out canoes. There has been biased attention of tropical marine fisheries towards coral reef-associated fisheries with little attention to other habitats such as seagrass meadows. Large amounts of fisheries are also associated with seagrass meadows which contribute substantially to small-scale fisheries through the provision of nursery, breeding and feeding grounds for numerous marine species that are exploited by coastal communities. However, critical information on some aspects of seagrass associated fisheries such as species assemblages and exploitation are limited. Using Creel survey and Underwater Visual Census (UVC) this study characterized the fisheries resources associated with seagrass meadows, their exploitation patterns and fishing impacts in Gazi Bay. Catch composition, species diversity, catch trends and threats to seagrass meadows and associated fisheries were evaluated over one year. Five fishing gears were observed in the seagrass meadows; basket traps (75.1%), hook and stick (10.8%), nets (7.8%), handline (4.9%), and speargun (1.4%). Overall a total of 113 species belonging to 55 families were recorded from catch assessment and Underwater Visual Census (UVC). A total of 85 species were observed from the creel survey while Underwater Visual Census recorded 33 species. Despite the high diversity in creel survey, only seven species accounted for 72.8% of the total catch by number dominated by Leptoscarus vaigiensis (30.8%). Others included, Scarus ghobban (10.2%), Lutjanus fulviflamma (10.1%), Lethrinus lentjan (7.6%), Lethrinus nebulosus (6.1%), Plotosus lineatus (4.3%) and Siganus sutor (3.6%). The catch rate was highest in the basket trap vi gears, at 3.5 ± 1.7 kg/fisher/trip (± SD) while handline recorded the lowest catch rate at 2.6 ± 1.2 kg/fisher/trip (± SD). There was significant variation in catch rate among the fishing gears (Kruskal-Wallis, p = 0.0187). The seven dominant species L.vaigiensis, S. ghobban, L.fulviflamma, L. lentjan, P. lineatus, L. nebulosus and S. sutor recorded mean lengths of 16.8 cm, 16,1 cm, 16.7 cm, 15.5 cm, 18.3 cm, 13.3 cm and 19.3 cm respectively. Forty-one percent (41%) of individuals from the top seven dominant species were immature. All gears recorded a proportion of immature individuals from the dominant species indicating the impact of gears on the fishery. There is a need for effective gear-based management measures for the seagrass fishery in the bay to protect key species such as the dominant observed in this survey for the sustainability of the fishery and ecosystems as well as protect livelihoods of the community depending on the fishery.