Population genetics of the hound needlefish <i>Tylosurus crocodilus</i> (Belonidae) indicate high connectivity in Tanzanian coastal waters

The hound needlefish Tylosurus crocodilus (Belonidae) is a highly demanded fish in the local markets of Tanzania, but growing coastal population threatens its sustainability. As belonids are migratory fishes utilising various parts seascape, increased fishing pressure may disrupt connectivity patterns on different spatiotemporal scales and disaggregate populations. Using COI gene, this study assessed genetic structure, patterns, historical demography T. collected seven sites spread along Tanzanian waters. Results showed fourteen haplotypes with low overall nucleotide haplotype diversity. Pairwise FST comparisons revealed no significant differences among sampled sites, except for northernmost site (Tanga) an island south (Songosongo). Analysis molecular variance (AMOVA) non-significant structure populations (FST = 0.01782), suggesting fishery across waters exploits same population. Moreover, there was correlative relationship between pairwise geographic distances, rejecting isolation by distance hypothesis. However, neutrality tests mismatch distribution analysis that recent demographic expansion might exist. Empirical evidence panmixia suggests high connectivity. In combination diversity, management should be directed to actions prevent diversity loss effect drift