Above a river south of Halifax, the sky darkens to a deep indigo – a signal to millions of baby eels to emerge from under the rocks and crevices of the brackish water. They wriggle near the surface like spermatozoids, pushing against the current.

Making it this far was a feat. They drifted thousands of kilometres as larvae on ocean currents from the Sargasso Sea, landing on the eastern coasts of Canada and Maine. By then, they had transformed into baby eels – or elvers – translucent but for two black specked eyes.