Paradise Found: Discovering Diversity in the Sharks and Rays of Sri Lanka

The 28 year civil war in Sri Lanka had hindered fishery data collection in Sri Lanka’s eastern and northern coast. Fishery surveys are ongoing since August 2017 and to date, we have surveyed 80 days in Valaichchenai (east),... [ view full abstract ]

The 28 year civil war in Sri Lanka had hindered fishery data collection in Sri Lanka’s eastern and northern coast. Fishery surveys are ongoing since August 2017 and to date, we have surveyed 80 days in Valaichchenai (east), 22 days in Jaffna (north), 6 days in Negombo (west) and 22 days in Tangalle (south) to fill in this data void and to update the current list of Sri Lankan elasmobranch species. All elasmobranchs recorded are identified to the lowest possible taxonomic level (n=1666). In addition, opportunistic morphometric and maturity data (n=296 sharks; 413 rays) and, tissue samples are being collected (n=118 sharks; 76 rays). Fishers are interviewed about catch details including location and fishing gear used. The most abundant species of sharks were Rhizopriodon oligolinx, Carcharhinus brevipinna and Carcharhinus falciformis. While 95% of all males of Carcharhinus brevipinna are mature, only 20% of males of Rhizopriodon oligolinx are mature. Thus far, we have recorded mobulid rays only at Negombo and Valaichchenai. The most frequent species is Mobula japanica (59%) which is consistent with our previous study conducted at Negombo and other southern markets from 2010 to 2014. It is noteworthy that 80% of all non-mobulid rays landed belong to two ray species viz Neotrygon indica and Brevitrygon cf. imbricata, which are classified as not evaluated and data deficient respectively by The IUCN Red List. We intend to begin catch per unit effort computations and stock assessments to better understand the sustainability of this fishery in Sri Lanka.