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The Fish kill!

Large-scale death of fish in water bodies is a wake up call
04:00 AM Jul 08, 2024 IST | ARIF SHAFI WANI
the fish kill

Large-scale death of fish in Chuntkul, an outflow channel of Dal Lake is a serious ecological concern. It was shocking to see hundreds of fish including large ones and fingerlings floating on the surface of Chuntkul today.


More shocking was how several people jostled to take their share of dead fish for cooking or sale! We have to understand that the phenomenon of fish kill happens in peak summer, but we must treat it as a wake up call. Fish kill could have happened due to the high pollution load in Chuntkul.
Chuntkul acts as a catalyst in maintaining the water budget of Dal’s ecosystem as its surplus waters flows through it into river Jhelum through Ram Munshi Bagh and Gaw Kadal. Ironically, the water channel has been devoid of sustained cleaning or dredging drives in the last several years.


Back side of Chuntkul has turned marshy and emanates a pungent smell with rise in temperature. In absence of chain-link fencing or abutments, unscrupulous people throw used material and garbage on its banks near Barbarshah locality.


Chuntkul’s condition is worst near Gaw Kadal side with weeds overwhelming the entire water surface. Ironically, drains of adjoining localities are directly emptied into Chuntkul by two dewatering stations severely affecting its flora and fauna. Instead of taking measures to restore the glory of Chuntkul, it is being polluted. From the source of fresh water, Chuntkul has become a source of pollution for locals, killing its flora and fauna including fish. The problem is compounded due to lack of regular circulation of water due to closure of Gaw Kadal regulatory gate through which water of Chuntkul flows in river Jhelum.


It is a fact that water bodies in Kashmir are facing an onslaught of encroachments and pollution. Experts have been expressing concern over the large-scale mortality of fish in our water bodies from last several years.


In May last year a large number of  fish were found dead in  Dal Lake.  During summer, there is large Biochemical Oxygen Demand (BOD) and due to depletion of oxygen and pollution load, some species of fish die.


Such incidents have also taken place earlier in Dal and Nigeen lakes. If waters are stagnated or organic, waste level is high, and fish mortality can happen.


Studies have shown that fish deaths in Dal Lake were the result of post-wind mixing up of bottom hypoxic waters with upper layers causing oxygen deficiency in the water column. Strong winds overturn the water column resulting in mixing up of anoxic, hypoxic bottom waters with upper layers. Subsequently this leads to oxygen deficiency in water and instantaneous fish kill.
Some experts claim that extensive summer de-weeding could also cause depletion of dissolved oxygen because aquatic plants and weeds produce oxygen in the process of photosynthesis.
In 2012, hundreds of fish died in Nigeen Lake mainly due to change in physico-chemical parameters propelled by high pollution levels. In 2010, death of fish in large numbers was witnessed in Wular Lake in north Kashmir.

Two species of fish Crossocheilus diplocheilus and Gambusia assinis are mainly affected in those water bodies, which have high concentrations of mosquitoes as they feed on their larva.
The decomposition of organic matter causes hypoxic conditions in fragile water systems, leading to an increase in ammoniacal nitrogen, which is highly toxic for fish.
Last year capturing of a fish resembling Alligator gar in the Dal Lake had set alarm bells ringing among the scientists who fear that the presence of non-native fish species could spell doom on the eco-fragile flora and fauna of the water body.

Fingerlings are very fragile and fish kill of this type is witnessed frequently in Dal and Nigeen lakes. Depletion of dissolved oxygen in water bodies due to point source of pollution ingress, algal blooms may arise due to poorly handled maintenance procedures of Sewage Treatment Plants (STPs) which is non-conducive for fingerlings to survive.

Some experts state that the fish deaths were caused by thermal stratification, which occurs when two types of steam with different temperatures come into contact. The temperature difference causes colder and heavier water to settle at the bottom of the pipe while allowing the warmer and lighter water to float over the colder water.

But it is largely believed that high nutrient load due to eutrophication, excessive weeds coupled with low oxygen seems to be the possible reason for fish kill. Harmful algal toxins can also complicate the situation and can be an addendum to the already present factors.

There is a need to conduct scientific studies to ascertain causes of fish mortality. It is the responsibility of the authorities to ensure regular water circulation in water bodies. As stakeholders, we have to join hands and contribute our bit to ensure that our water bodies are clean and pollution free. We have to ensure that we protect the flora and fauna of water bodies. We have to understand that our existence depends on these bodies!

Author is Executive Editor, Greater Kashmir