Spatial assemblage and interference competition of introduced Brown Trout (Salmo trutta) in a Himalayan river network: Implications for native fish conservation

Introduced Brown Trout (Salmo trutta) exhibit competitive dominance over native Snow Trout (Schizothorax richardsonii) in the Tirthan river network of the Great Himalayan National Park Conservation Area, posing a significant threat to local fish populations. The study found that adult Brown Trout outnumbered native adults by 66.1% to 33.9%, while Snow Trout fingerlings were more abundant (61.9%) than their invasive counterparts (38.1%). Analysis revealed distinct spatial patterns, with non-native trout occupying higher-order streams and natives restricted to lower-order ones. Redundancy analysis identified key environmental variables influencing species distribution, while clustering showed six distinct subgroups based on abundance data. The findings underscore the urgent need for management interventions to prevent further spread of Brown Trout, including enforcement of national policies like 'The Indian Invasive Species Act.'

Sharma, A., Dubey, V. K., Johnson, J. A., Rawal, Y. K., & Sivakumar, K. (2021). Spatial assemblage and interference competition of introduced Brown Trout (Salmo trutta) in a Himalayan river network: Implications for native fish conservation. Aquatic Ecosystem Health & Management, 24(2), 33–42. https://doi.org/10.14321/aehm.024.02.07