From tonight, knives out for monster fish lurking in Sukhna depths

Chandigarh: Big, commercial carps as well as the old exotic giants inhabiting the murky depths of the Sukhna Lake are in for a cleansing operation, commencing Monday for 10 nights in a row. The fish-thinning exercise is aimed at creating conditions for better breeding of small and moderate-sized fish species (minnows) and introduction of native carps by the UT animal husbandry and fisheries department.The fish-thinning and stock-taking operation will be carried out on a lease basis and is scheduled for March 13-22, from 8 pm to 6 am. The fishing will be conducted with gill nets of specific mesh size not less than 6 cm from knot to knot so that small fish are not removed. The scheduled operation will be the third such instance of systematic removal of large fish from the Sukhna in contemporary history, the earlier ones were staged in 2010 and 2015. “The Covid lockdowns delayed our plans for removal of big fish and restocking of the seed of native carps. Since a lot of undesirable species from aquariums and other commercial fisheries sources are dumped in the Sukhna regularly, we need to know what exactly the lake holds in terms of fish diversity,” a senior officer of the fisheries department told TOI.In furtherance of the objective of “ecological balance” of the lake, the operation has been planned in consultation with the forests and wildlife department and the Panjab University’s zoology department. “The Sukhna is a small lake unlike larger water bodies and does not have a regular supply of flowing water. Such lakes have specific requirements of ecological management of flora and fauna which are sensitive to change. The removal of big fish will allow better feeding availability for small fish, which are preferred by migratory birds. The decision to remove big fish was taken on the recommendations of the forest department as unusual mortality was reported in the last rainy season and a number of fish considered ‘undesirable’ for the lake, such as the Maghur cat fish, came to the surface after the release of excess water from the regulator gates,” the senior officer added.A part of the fish netted would be handed over to the zoology department’s researchers in furtherance of ongoing research to improve the ecology of Sukhna and study changes in fish diversity. Alarm bells rang after recent photographic evidence surfaced of exotic aquarium specimens such as the Amazonian Sailfin catfish caught by birds. Birds struggle to swallow such exotics because they have not co-evolved with these foreign species and are known to suffer mortality.Emeritus Professor of Fisheries at the PU, the late Prof MS Johal, had explained the logic of big fish removal on the eve of the October 2015 operation at Sukhna. Prof. Johal had then told the TOI: “'All over the world, specific fish harvesting strategies are adopted for sustainable yield and to keep a check on size and number of commercial fishes so that they may not affect growth of other fishes and aquatic organisms. To maintain the best water quality of Sukhna, a good number of local fish species have been introduced in several phases. During rains, Sukhna receives water from its catchment area, bringing a heavy load of nutrients. As water has never been drained (except 2-3 times in its history), the nutrients are being added every year. The Sukhna supports about 35 fish species, out of which 5-7 are considered to have great commercial importance. Keeping in mind the size and depth of lake and the decreasing trend of post-monsoon water levels, the existence of these fish beyond a certain size is not advisable from the ecological management point of view. Efforts must be made to remove nutrients from the lake...”