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222 || AWSAR Awarded Popular Science Stories - 2019
brown trout was extirpated! A “complete wipe-out”fromtheentiresystem.Surprisingly however, the native snow
trout still thrives- and in good
numbers! When we promote selfish invasions, nature often has to intervene to revive the perfect ecological balance by favouring natives over invaders. This phenomenon where nature governs priorities by eradicating an invasive from the system is an ecological principle called “Priority Effects”, which seems lost in the old books of ecology!
Our team from WII had
conducted surveys just
months prior to the flash flood,
confirming the presence of
brown trout in abundance
by then. Since 2012, however, no study was conducted to confirm the after-effects of this natural stochasticity. As a part of the regular ichthyofaunal investigations under the National Mission for Sustaining the Himalayan
Ecosystem (NMSHE) project, we conducted regular surveys along the complete river stretch from June 2017-June 2018. To make sure we do not miss out on any evidence, the entire river stretch was sampled at an intensive 500 m interval. For this, we trekked along most of the river stretch, at higher elevations, as there were no roads. A total of 18 surveys with 124 rounds of samplings across all points were carried out throughout the year. We reported a stable snow trout population, however not a single brown trout was
encountered.
As the millennial research
often demands immediate results, we tend to ignore the historical ecological trends underlining the present scenario. This leads to predispositions that any ecological setting is nothing but a “chance event”. Rather, events like these where a
Continuous natural modifications of the river hydrology over the years make the native fishes much more resilient to natural stochasticity, thus, helping in their retention. Nevertheless, there is a condition to it, failing which nature would not act! The river must be “undammed” and its flow unobstructed by human interventions.