The J&K government has attributed the deaths of thousands of fish in Dal Lake in Srinagar to thermal stratification. An in-depth study by the country’s leading fisheries university, the Central Institute of Fisheries Education, Mumbai, in December 2022, had heralded widespread pollution making the ecosystem of lakes unviable for fish production.
A research paper titled Assessment of Fisheries and Management: Insights from Dal Lake, Kashmir published by Indian Journal of Extension Education drew a gloomy picture of Dal Lake, a major attraction for tourists visiting Kashmir and one of the major water bodies for fish in Kashmir.
Pollution has severely affected the harvesting of Schizothorax fish and destroyed the native fish spawning grounds. This impact was very severe from 2007-2008 and had a huge effect on the total fish production in Dal Lake, the study pointed out.
Data on harvests of Schizothorax, a local fish species known as Kashir gaad or Snowtrouts, from the lake between 1989 and 2019, show a downward trend from about 240 tons in 1989-90 to less than 100 tons in 2018-19.
Carp were introduced to Kashmir in 1957. The carp catch has increased from 190 tonnes in 1989-90 to 350 tonnes in 2019. The total catch of fish, however, does not show significant growth as the catch peaked at 475.65 tons in 2003-04. The annual catch from Dal Lake, including all fish stored and not, was 450.5 tons. The total catch of fish hit a low of 262.03 tons in 2007-2008.
The total harvest of fish from the lake hasn’t increased much in recent decades. The lack of proper governance, political regulations and coordination between government agencies and fishermen adds more negative impact. As noted, most policies have been formulated without considering fishermen’s perceptions, the study points out.
The study suggested that the alkalinity of lakes increased from 69.5 milligrams per liter in 1974-76 to 101.75 in 2018. Alkalinity measures a body of water’s ability to neutralize acids and bases to maintain a pH level quite stable (acid-water ratio). , essential for fish and other aquatic life. He said the pH value of the lakes had risen from 7.4-9.5 in 1974-76 to 7-10. The pH value of a healthy lake should be below nine.
The chloride content of water has increased dramatically over the past two decades from 2 to 2.7 mg/l in 2007 to 10.3 mg/l in 2017, which could be due to drainage from catchment areas, raw sewage from houseboats and nearby settlements and organic runoff from floating gardens.
Climate change factor
The study also warned of the impact of climate change. The water quality of the lake has deteriorated due to reduced inflow from streams, possibly due to climate change in the Himalayan region. In addition, human settlements, hotels, floating gardens and even washing points on the outskirts have contributed to the slow death of the lakes, he added.
The study does not show any thermal stratification or increase in water temperature. Water temperatures in 1974-76 were 16.4 degrees Celsius, 15 degrees Celsius in 2006-07 and 16.4 degrees Celsius in 2018, he noted.
On May 26, much of Dal Lake was engulfed in the stench of thousands of dead fish floating ashore. The size of the affected fish, known as Gambusia species, is three to four inches. Our science wing has looked into the matter. The fish died due to the erratic weather which caused thermal stratification and a change in temperature at different depths in the lake, said Bashir Ahmed Bhat, vice chairman of the J&K Lake Conservation & Management Authority (LCMA).
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