If you restore it, they will come (back)

Hello! Welcome to the first edition of The Briny, a newsletter companion to my podcast, innovatively also titled The Briny. In the newsletter, I’ll bring you weird and wonderful discoveries from the underwater world, ocean-related news, and bonus content from the podcast. For this edition, we’re looking at a conservation success story: alewife.

But first, the weather.

🌊 The Weather Report 🌊

Courtesy of the National Weather Service Forecast Office in Mt. Holly, New Jersey

Coastal Waters Forecast for New Jersey and Delaware:

“A weak back door cold front will slide through the region later today. Low pressure will develop offshore mid-week, though high pressure to the northwest will likely continue to dominate local weather. A cold front may impact the area late next weekend.”

Alewife (Alosa pseudoharengus) are a species of river herring native to the east coast of North America. Their range spans from Newfoundland to the Carolinas. They live most of their lives in the ocean, but they swim upriver to ponds and lakes in the springtime to spawn. A single alewife can make many return trips upriver, unlike salmon, which die after their spawning season. The juvenile alewife help maintain the water quality of their ponds and lakes while they grow big enough to migrate downriver to the sea.

But, amazing as that feat is, alewife’s great contribution to ecosystem health isn’t really anything that the fish itself does. Alewife are a nearly universal prey species, feeding everything from cod to river otters to osprey. When the population of alewife is healthy, they can help support the entire food web. Alewife were also a historically significant fishery for the Passamaquoddy people, who called it “the fish that feeds all.”

Alewife are in trouble. While not on the endangered species list, they are considered a “species of concern.” That’s due to several factors:

Overfishing: Once a commercially significant fishery, alewife landings crashed in the 1970s and hit bottom in the 1990s. Several states imposed a moratorium on catching river herring (the larger category that includes alewife) to try to revive their populations.

Pollution: The usual suspects for water pollution, namely agricultural runoff and industrial pollution, affect the quality of the rivers, ponds, and lakes that alewife rely on to reproduce.

Habitat loss: Alewife need to get upriver to lakes and ponds of spawn. Human interference, in the form of dams, roads, and other infrastructure, can block river herring from returning to their natal streams.

Since the late 1990s, Maine has removed (or built fish ladders around) dams that had blocked river herring for centuries. And those efforts have shown results. Alewife counts across the state have trended upward since 2000, according to the Atlantic States Marine Fisheries Commission.

Individual rivers have seen dramatic change: until 2021, 6 dams blocked Vassalboro’s China Lake for centuries, keeping alewife in the nearby Kennebec river from reaching this historic spawning ground. After removing or building fish ladders around those dams, China Lake, which I visited for an episode of The Briny, logged over 3 million fish.

“Alewives are resilient,” said Landis Hudson, executive director of Maine Rivers, when I interviewed her in 2023. “They will take full opportunity of whatever improvements you make.”

Unfortunately, that’s another way alewife distinguish themselves from other fish species, like salmon, whose number still haven’t recovered despite habitat restoration efforts.

Elsewhere in their range, alewife numbers are still deeply depleted. Even in Maine, the alewife numbers are nowhere close to the tens of millions that scientists estimate they might once have been.

But improvements in the Kennebec, Androscoggin, Saco, and St. Croix Rivers offer hope. Given the chance, these fish could one day return to something like their historical abundance.

🐟 Check out the alewife migration in person: Maine Rivers has published this handy guide to good viewing spots for the migration, which lasts from mid-May to mid-June.

Scientists with Chicago’s Field Museum and the Charles Darwin Foundation recently published an article describing a new species of tiny, blue octopus from the Galápagos Islands, named Microeledone galapagensis. And it is a cutie.

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