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Biography

R R A R. Shirantha has completed her M. Phil in Zoology from University of Kelaniya, Sri Lanka, conducts research on faunal conservation, works as a Research Officer at NARA, premier research organization in Sri Lanka. She has published more than 32 national/international level research papers. She is a member of freshwater fish expert committee of IUCN, Wild Life Conservation Department and National Species Advisory Group.

Abstract

In late 1970s the endemic food fish species Labeo fisheri was common in rocky streams in the River Mahaweli of Sri Lanka though it having not been recorded to science during last one and half decades. The intentional socio-ecological survey carried out from 2008 to 2010 through skin diving, 1-3cm gill and cast netting, visual observation and questioners confirmed existence of L. fisheri at 12 sites accounting 98 Km2 occupancy area in Mahaweli cascade systems of >25m height, >50 m long large rock filled dams over 15 locations with no fish ladders. Recorded refuge populations were male dominant with <0.5 individuals/km2 population size and 38 cm maximum length. The observation made on unsuccessful attempts of spawning L. fisheri move into up-streams, <2 site records in ancient irrigation tanks and low densities isolated populations in up-stream large deep >5m rock pools and past experience of local people proved, the river impoundments in late 1980s have possessed and are possessing a critical ecological issue contributing for its population decline. The sequential and sociological studies evident a well-established fishery in late 1970s, good demand and its no contribute to inland fishery at present. Despite of almost all refuge populations are in protected areas and are protected under provision of two parliament Acts, due to weakness in law enforcement L. fisheri is exploited. 100% local people found not aware the legal aspect. Over 85% rural people showed affinity to eat L. fisheri due to delicacy. Hence, a single sighting is enough L. fisheri to being fished with either plant derivative poisons or blasting, thereby refuges become an illegal animal protein source for forest people. Ecological studies showed habitat quality degradation due to high siltation, use of agrochemicals, river drying, sand/gem mining, colonization of alien grazer Hypostomus plecoptomus which is having 92% food niche overlap possess threats. Study on reproductive ecology was not succeeded since there was no record on juveniles, fry or indigenous knowledge. Their ex situ conservation through captive breeding was found to a challenge, as all died when trying to rear at cement tanks/earthen ponds at several times. However, SWOT analysis showed possibility in translocation practice for in situ conservation with water depth 5-10 m, dissolved Oxygen >6 mg/l, pH 7-7.5, temperature 18-22°C. The present study showed negative impacts of hydro energy development projects on localized food fish populations. Therefore, proper mitigatory actions must be taken when constructing cross dams over the rivers in future. At the same time actions should be taken soon not allowing remaining L. fisheri to go into a viable population size. Since L. fisheri existence and spawning were found as habitat specific, construction of effective fish ladders at damming sites are very important. In addition to these adopting effective law enforcements, conducting awareness programs, strictly prohibiting catching of L. fisheri even for research purposes would be better in situ conservation strategies. The future research on induced breeding of L. fisheri would also be logical and very crucial.