Threats to the indigenous freshwater fishes of Sri Lanka and remarks on their conservation
Sixty-two freshwater dispersant (26 endemic), 26 saltwater dispersant and 20 exotic fishes have been recorded from Sri Lanka's inland waters. The discovery of nine new species of freshwater fish during the past decade suggests that Sri Lanka's fish fauna is not yet well known and that further discoveries can be expected. All the new species, and almost all the endemic ones, have been recorded from forested areas in the foothills of the southwestern wet zone and the Knuckles hills. The known ranges of many species are exceedingly small; almost all of them are habitat specialists. 25 species have at least two strong habitat preferences (in almost all case, shade being one), though a majority (32 species) have none. Habitat alteration is therefore the greatest threat to their survival. Eight freshwater fish species are considered endangered and a further five, vulnerable. Three species are rare, 18 common and 13 abundant. All but two of the endangered species and all the vulnerable species are endemic in Sri Lanka. Nine species are each restricted to only one drainage basin, and seven have a known range < 50 km2. Three species of diadromous gobies known only from small populations are considered vulnerable. Examination of the existing threats suggest that deforestation, the widespread dispersion of exotics, pollution caused by agricultural chemicals and increasing pressure from the food fishery present the greatest threats to fish populations. While the endemic fishes are restricted to or most abundant in the wet zone, the overwhelming extent (> 95%) of Sri Lanka's nature reserve areas are in the dry zone. A programme to maintain self-sustaining captive populations of the endangered species is urgently necessary.
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences biologiques fondamentales et appliquees. psychologie