Fishy project

Interlinking of rivers may impact aquatic biodiversity

By Sreedevi Jacob
Published: Saturday 31 July 2004

if the findings of a recent study were to be believed, the Union government's proposal to interlink rivers across the country would adversely alter the habitat of a variety of fish. The study, by scientists from the Cochin University of Science and Technology and the Kerala Agricultural University, was conducted as part of the project 'Fish germplasm, inventory, evaluation and gene banking of freshwater fishes'. Of the 44 rivers in Kerala, fish species of 32 were studied.

The researchers analysed the relationship between 53 parameters of the river systems and the abundance of fish during the pre-monsoon, monsoon and post-monsoon seasons. The main chemical parameters included the nutrient level, and the alkalinity and acidity of the water. The physical parameters included presence of a gravel or sand-grain riverbed, gravel size, river flow, and overhanging and underwater vegetation.

The researchers found that seven of the state's 31 endemic fish species were found only in certain stretches of the rivers. Reason: 70-90 per cent of the species' distribution pattern was directly correlated with the presence of certain physical parameters. "Even in the same river, when the critical parameters changed from place to place, there was an absence of a particular species,'' informs B Madhusudana Kurup, the lead researcher.

As per the researchers, this finding is indicative of a catastrophe ahead -- once the rivers are interlinked, parameters of big rivers will supersede those of the smaller ones, affecting the fish species of the latter. "Fish are very sensitive and unless the gravel size is what they are used to, spawning instincts can change and breeding patterns can alter. Moreover, height of the underwater vegetation is crucial for the eggs to hang on to," explains Kurup, adding: "Therefore, it is a must to think twice before executing the ambitious interlinking project."

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