GENETIC STRUCTURE OF CRIMSON JOBFISH, Pristipomoides filamentosus (VALENCIENNES, 1830) POPULATION OF THE SOUTHWEST INDIAN OCEAN

Abstract

Crimson jobfish, Pristipomoides filamentosus is a commercially important tropical snapper. Their aggressive nature and relatively large size makes them more vulnerable to fishing gears. In addition it is vulnerable to overfishing due to low rates of growth and recruitment, high natural mortality and prolongation of the attainment of sexual maturity. P. filamentosus in South West Indian Ocean has shown signs of decreased abundance of yields and catch per unit effort beyond sustainable levels. This highlights the need for more directed and stringent fisheries management. Therefore if the genetic population structure of a species is known, the distribution of subpopulations in mixed fisheries can be estimated and this will ensure long term management of fish stocks. In the present study, genetic connectivity and population structure of P. filamentosus in SWIO was studied in order to clarify whether its populations are genetically distinct or admixed. The entire research work was conducted from July 2012-April 2013.Samples were collected from Kenya, Tanzania, Madagascar, Comoros, Seychelles, Mauritius and South Africa from the artisanal and commercial fishers of the respective countries. DNA was extracted using purelink kit, amplification was done by 15 hyper-variable nuclear microsatellites and mtDNA cytochrome b markers, statistical softwares used for genotyped data were Genemapper, GeneAlex, Powermarker and Darwin and Arlequin, Bioedit, CLC main work bench and network for sequenced data. Results indicated significant and moderate (mtDNAFST=0.062; microsatellites FST=0.100) genetic differentiation of P. filamentosus in Southwest Indian Ocean. Three distinct populations were detected across the region (K=3), it was also revealed that populations are expanding (D=-1.5387). It is recommended that countries sharing the same population of P. filamentosus should enforce coordination and cooperation in the management of this species to enhance sustainable harvesting