The Vembanad fish count, an annual survey to evaluate fish varieties in Vembanad Lake, has recorded 100 species, an increase in comparison to the previous year.
The fish count, 14th in a series of surveys, was conducted in different parts of the lake last month under the aegis of the Community Environment Resource Center, a field academic unit of the Ashoka Trust for Research in Ecology and Environment (ATREE), a non-governmental organisation.
A team consisting of members of the ATREE, researchers and fishermen conducted fish counts in the southern and northern parts of the lake in two phases. Releasing the details of the survey here on Tuesday, Anu Radhakrishnan, senior programme officer, ATREE, said 92 fin fish species and eight shellfish species were recorded in the survey. Seventy-six species of fish were found in 2020, while the figure was 98 in 2019.
The team, which surveyed the southern side of the lake on August 10, 11 and 12, recorded 48 species. Fifty-two species were identified from the northern side, where a survey was conducted on August 17, 18 and 19.
Mr. Radhakrishnan said that pearl spots were found in good numbers in the lake. Alien species such as iridescent shark catfish (koori vaala), tilapia and red belly fish were spotted from different parts of the lake. As per the accounts of inland fishermen, there was a decline in the number of freshwater prawns (aattu konju) since the 2018 floods.
Apart from evaluating fish species, a scientific analysis of water in the lake was conducted as part of the programme. The pH value varied between 5.9 and 6.2. The highest salinity recorded was 6.8 ppt. The level of dissolved oxygen varied between 2 and 4 ppm. Dissolved oxygen levels of 4-5 ppm are considered as the minimum amount needed to support a diverse fish population, while levels below 3 ppm are considered stressful.
