Diversity, distribution, and conservation status of fish species in Kallar Stream, Achankovil River, Western Ghats of Kerala, India

Abstract

The current study presents the findings of fish species inventories conducted at 12 locations in ‘Kallar’, the perennial tributary of the undammed Achankovil River that flows through the Achankovil Reserve Forest in Kerala State. A new checklist of ichthyofauna is prepared, by adding the updated scientific names, which comprises 35 species from 27 genera, 13 families, and eight orders. In order of abundance, Opsarius bakeri, Salmostoma boopis, and Garra surendranathanii were the most prevalent species in the Kallar tributary. Eight of the total species documented are listed as threatened on IUCN Red List. The study reports the presence of a poorly known smiliogastrin cyprinid, Dawkinsia lepida for the first time in the Achankovil River as well as the range expansion of the threatened catfish, Batasio travancoria, and the Malabar Spiny Eel Macrognathus guentheri to the Kallar tributary. The study also reports a species of Balitora from Kallar, distinct from its congeners in several morphometric and meristic characteristics. The absence of any non-native fish species in the study area revealed the pristine nature of the stream habitat. A comparison of diversity indices with the available pre-flood study revealed that the fish species composition in Kallar stream has not altered as a result of the 2018 catastrophic flood. The main existing threat is the practice of destructive fishing at high levels by local communities adjacent to but outside the forest area during the dry season by damming the streamlets and then applying plant-based piscicides. It is recommended that fishing be banned during dry season because this is the time of year when the majority of the upstream fishes breed. The existing environment and fisheries acts should also be strictly enforced. For the sake of future conservation, the competent authorities should see to it that the last remaining natural forest cover in the Kanayar and Kallar ranges are safeguarded from being converted to forest plantations.