Alewife

In his System of Nature, A. D. 1776, Linnæus declares, “I hereby separate the whales from the fish.” But of my own knowledge, I know that down to the year 1850, sharks and shad, alewives and herring, against Linnæus’s express edict, were still found dividing the possession of the same seas with the Leviathan.

I saw in Cohasset, separated from the sea only by a narrow beach, a handsome but shallow lake of some four hundred acres, […] and, after the alewives had passed into it, it had stopped up its outlet, and now the alewives were dying by thousands, and the inhabitants were apprehending a pestilence as the water evaporated.

Alewives are anadromous fish: Born in freshwater, they spend their lives in the ocean, returning annually to their birthplaces to spawn. Until colonial-era dams cut off their migration, hundreds of thousands of alewives would have come pouring into Rogers Lake [Connecticut, USA] every spring — and into other lakes like it along much of the Eastern Seaboard. Farmers used to apply them to their fields as fertilizer, and all along the coast, river herring festivals celebrated their arrival.