Study by Chennai fisherman shines light on changing sea patterns and declining catch

Chennai fisherman study climate change impact on traditional fishing seasons, highlighting shifts in weather patterns affecting livelihoods.

“The kadal (sea)is our amma (mother), and kaathu (wind) is our paattaan (grandfather),” says S. Palayam, a 60-year-old fisherman from Urur Kuppam in Besant Nagar. 

At the release of ‘Sea Changed; Seasons Changed: A Fisher Science View of Climate Change’, Mr. Palayam, principal author of the study, and Nityanand Jayaraman, social activist and co-author of the study, on Saturday presented data comprising observations of the sea on 1,179 days between September 2018 and October 2023, backed by the former’s traditional knowledge of the winds and currents, beliefs, and folklore.

Highlighting the changes in two seasons in fishers’ calendar — kachan, characterised by southerly winds and currents, and vaadai, characterised by northerly winds and currents — the study says until about 30 years ago, vaadai season would set in by end of September and withdraw by third week of January, followed by the onset of kachan season. However, data shows that kachan is 33 days shorter than usual, vaadai sets in and withdraws later than normal, and there’s a disruption in the transition period between the two seasons in mid-September to end-October that typically is a highly productive period for fishers.

It is important to note that the colloquial language used by fisherfolk in Chennai is likely to be entirely different from fishers’ lingo in other coastal districts of Tamil Nadu. 

The old normal

During the auspicious Tamil month of Aadi, mid-July to mid-August, when the southwest monsoon is in full swing west of the State, a phenomenon called vanda thanni happens. “Like the saying Aadi vellam thedi paayum, the flow from Cauvery gushes into the sea, bringing with it Kollidam paasi (algae), dirt, and a lot of fish,” says Mr. Palayam. 

From mid-September to mid-October, there used to be a gentle breeze with weak currents in bright blue clear waters. Shore seine fishing during this time yields anchovies, mackerel, which move in shoals in nearshore waters.