Sri Lanka, Sept. 9 -- For India and Sri Lanka, the sea has never merely been geography. It has been livelihood, memory and civilisation. Fishing communities on either side of the Palk Strait have for generations inhabited a maritime world older than the political boundaries that now divide it.

Fish has nourished households, sustained coastal economies and created cultures whose relationship with the ocean cannot easily be reduced to coordinates on a map. The economic story is equally compelling. India today produces nearly 20 million metric tonnes of fish annually, supports the livelihoods of roughly 30 million fishers and fish farmers, and is the world's second-largest fish-producing country.

Sri Lanka, despite its vastly smaller size...