A survey of fish species in Vembanad, conducted by Ashoka Trust for Research in Ecology and Environment here, has recorded the presence of 43 species of freshwater fish and five species of shell fish in the backwaters and riverine areas. The study was the ninth in the series of annual surveys held by the non-governmental organisation.
Forty-five species of freshwater fish and five species of shell fish were found in the survey last year.
The fish varieties traced in the new survey were among about 70 species found in different surveys organised earlier.
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Increase in acidity levels in water had led to a decline in fish count, especially in the Chithira, Marthandam and Methran Kayal areas, T.D. Jojo, project coordinator, told
The pH value of water was 4 to 5 in areas which recorded lower fish count. Pesticide content from agricultural fields reaching the backwaters resulted in an increase in acidity levels, adversely affecting the breeding of fish, he said.
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The opening of the Thanneermukkam bund in April had facilitated breeding of shell fish in nearby areas. A decrease in summer rain this year also contributed to breeding of clam in areas such as Muhamma and Kainakari.
The survey was conducted at 15 locations by a team consisting of members of the NGO and researchers from the College of Fisheries. About 100 volunteers took part in the programme. The services of expert fishermen were also utilised.
The fish count project was flagged off on Sunday at the Kaippuram jetty. A session held at Pulimoottil Convention Centre in the evening was inaugurated by district panchayat president G. Venugopal.
An orientation programme held for the survey team prior to the programme was inaugurated by S. Mahesh, Deputy Director of Fisheries.