Non-native fishes in the Indian Himalaya: an emerging concern for freshwater scientists

Abstract

ABSTRACTAnthropogenic activities impose major threats to global biodiversity, compounded by changing climatic variables. Freshwater ecosystems are amongst the most vulnerable habitats, integrating multiple pressures across catchment landscapes. Introduction of non-native fish species exerts multiple direct and indirect impacts on native species and the ecosystems of which they are part, with further impacts on the socio-economic wellbeing of communities. Field studies and an in-depth literature survey have recorded 15 non-native freshwater fish species from the Indian Himalaya. Three of these species (common carp, brown trout and rainbow trout, all highly invasive fish species globally) were documented from multiple locations between 2010 and 2017, raising environmental concern among scientists. In the wake of changing climatic variables and a range of linked population, land use and river impoundment and conversion pressures across the Indian Himalaya, there is an urgent need to understand the behaviour of these non-native fish species and identify factors which provide them an ecological advantage over native fish species. This can support a case for cessation of stocking with alien species. Further collection of long-term field data, integrative quantitative models, public awareness and education programmes could greatly assist in addressing these knowledge gaps and identification of effective control measures.