Vembanad stifling under human intervention, gasps for breath

Call for urgent intervention to conserve the wetland system spread over 2,033.02 sq km

Not less than three decades ago, local markets in upper Kuttanad regularly played host to scenes of live, loud, and fierce bidding wars between fishermen collectives.

The event used to be a good draw as the items for sale will be the indigenous fish species from polders along the Vembanad lake basin. Often bids used to attract prices as high as ₹50,000, depending on a host of factors, from season to proximity to the lake.

As time passed by, several of these markets became non-existent, so do the auctions they played host to.

For the majority who depend on it, Vembanad Lake now provides no more than a meagre living as the fish wealth is getting depleted by about 7,500 tonnes every year. As per estimates, about six to seven lakh people are dependent on the lake system for a living even as the number of fish species has declined markedly over the years.

The annual Vembanad Fish Count (VFC) conducted by the Ashoka Trust For Research in Ecology and the Environment (ATREE), in collaboration with the Kerala University of Fisheries and Ocean Studies, in the past two years noted a steady decline in diversity of almost all kinds of fin and shell fishes.

Fall in fish species

While the VFC in 2018, carried out at six locations - three each on the north and south of the Thannermukkom bund- recorded 117 fish species, the number fell to 98 last year. Of the total species spotted in 2019, 50 were found in the northern side and 48 in the other.

“Even if seasonal and spatial factors are to be considered, the difference is huge when compared to the 153 species recorded in a study in 1980,” explained Anu Radhakrishnan, programme officer of ATREE.

This sharp fall is primarily attributed to the annual closure of the bund, which causes disruptions in the hydrological cycle, sedimentation, and compromises migration of fish from the ocean.

“The silt that reaches the lake bed through the river affects organisms in the deeper habitats, forcing them to move out . Adding to this is the widespread use of stake net in the Kochi side during high tide, which scoops up even the brooding organisms,” added Mr.Radhakrishnan.

Of greater concern are the unrestrained extraction of the fishery and high toxic situations caused by agro-chemicals in the run-off water and petrochemical exhausts from boats, leading to biodiversity loss.

A recent study by the Kerala University of Fisheries and Ocean Studies in the 76.5 sq km Alappuzha-Thannermukkom sector of Vembanad reported 4,276 tonne of plastic garbage in the bottom sediments, which works out to 55.9 tonne per sq/km.

Shrinking depth profile

The study also pointed to the shrinking depth profile of the lake, from eight to nine metres in 1930s to the present 1.6 to 4.5 metres.

As Vembanad, stifling under human intervention, gasps for breath, experts have called for urgent intervention by the authorities concerned in conserving the wetland system, which covers an area of over 2,033.02 sq km.

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Printable version | Feb 18, 2020 11:56:08 AM |

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