SPATIO-TEMPORAL DYNAMICS OF THE MARINE AQUARIUM FISHERY AND RECRUITMENT OF REEF FISHES IN COASTAL KENYA

Abstract

Sustainable management of the marine aquarium fisheries in Kenya is challenged by limited information on the fishery and recruitment dynamics of target species at sufficient spatial, temporal and taxonomic scales. In order to bridge these information gaps, this study used a combination of data from fisher catches and ecological monitoring to assess spatial and temporal patterns of aquarium fishery and recruitment variability on shallow coral reef lagoons in coastal Kenya. Aquarium fisher catches spanning 6 years (October 2006 to December 2011) from 11 fishing grounds along the coast were examined for spatial and temporal variability. Catches were further monitored between September 2010 and December 2014 to assess potential gear-based overlaps in species selectivity. Underwater visual census surveys were conducted at five shallow coral reef lagoon sites for spatial and temporal patterns of juvenile reef fish recruitment. Results indicated 220 fish species in 36 fish families are exploited by the aquarium fishery, numerically dominated by Labridae (32%) and Pomacentridae (14%). Thirty-two species made up 80% of the aquarium fisher catches with the cleaner wrasse, Labroides dimidiatus being the most collected. Detrended Correspondence Analysis (DCA) associated some target species to specific fishing grounds, while results of nonmetric multidimensional scaling (nMDS) ordination revealed an influence of fishing modes (SCUBA vs snorkeling) on the species composition of the catches in all the sites. Results of Productivity and Susceptibility Analysis (PSA) performed to evaluate the vulnerability risk of 102 target species to the fishery ranked four species: Pomacanthus maculosus, Pomacanthus chrysurus, Amphiprion allardi, and Amphiprion akallopisos as highly vulnerable to the fishery, while seven species were at moderate risk of overfishing. Target aquarium species constituted approximately 12% of artisanal landings by weight and 8% by numerical abundance. Handlines and spearguns had the highest overlap in species selectivity with the aquarium fishery; while aquarium snorkel fishers had the highest potential overlap with the artisanal gears. Recruitment was observed all year-round peaking during December to March, but varied in intensity among species between years, seasons and months. Canonical Correspondence Analysis showed that live coral and reef rugosity as the main habitat predictors of reef fish recruit abundance. Dentrended Correspondence Analysis further showed that habitat associations were species-specific. The study addresses critical information gaps relevant to the management of the fishery. Overall, the study addresses critical information gaps relevant to the management of the marine aquarium fishery in Kenya and recommends measures for sustainable exploitation of the fisheries.