A little fish plays a big role in the food chain: Alewives return to rivers to spawn

ARI SHAPIRO, HOST:

Up and down the New England coast, nature lovers are flocking to rivers to witness an awe-inspiring spring ritual - thousands of little fish on a long voyage home. Nora Saks has this audio postcard from one of their migration routes in southern Maine.

(SOUNDBITE OF RIVER ROARING)

NORA SAKS, BYLINE: Right before it meets the sea outside of Portland, the Presumpscot River crashes through a rocky, tree-lined gorge. Aquatic ecologist Karen Wilson and I are perched high above the churning water, binoculars at the ready.

KAREN WILSON: Another osprey just took off with another alewife.

SAKS: A brown-and-white raptor soars for the canopy clutching a silvery, footlong herring.

WILSON: That's pretty impressive (laughter). This is a really close-up view of an osprey with a fish in its talons.

SAKS: Alewives spend most of the year in the Atlantic Ocean, but every spring they travel miles upriver to spawn in the very same lake where they started their lives, which means they're food for...

WILSON: ...Everyone and anything.

SAKS: Birds, mammals, fish, and even some people feast on alewives. And before it was super industrialized, this river had tremendous fish runs. Then dams and pollution halted their migration for centuries. We're actually sitting near the site of the first dam on the Presumpscot, which was removed in 2002.

WILSON: That allowed alewife and some of these other fishes to start moving up the river again for the first time in probably about 200 years.

SAKS: But their 11-mile journey is still full of peril. Fish that escape the gauntlet of talons and teeth must then maneuver their way up huge rapids.

(SOUNDBITE OF WATER FLOWING)

WILSON: I can imagine them coming up right here along the shore.

(SOUNDBITE OF WATER SPLASHING)

SAKS: Word on the street is that the alewives are now making their way into Millbrook.

I watch three or four fish make a heroic attempt to shimmy up a pile of boulders covered in just a trickle of water.

There they go. There they go. Oh, right back down. Another big - a big one's going for it. Nope.

Many try - all fail.

They get splashed on the rocks. Oh, my God. This is crazy.

When my heart has had about all it can take, I head two miles upstream to the alewives' final destination - Highland Lake. Here, they'll lay thousands of eggs before heading back out to sea.

(SOUNDBITE OF RIVER ROARING)

ROSS DONIHUE: I just saw two. Two just came through.

SAKS: Volunteer Ross Donihue is counting alewives for the local land trust.

(SOUNDBITE OF WATER FLOWING)

SAKS: Every few seconds, one dashes up the cement fish ladder, pass largemouth bass lying in wait and enters the calm lake - home at last.

DONIHUE: Ooh, there's another one - up to 50.

SAKS: Whoa, whoa, whoa.

DONIHUE: Great.

SAKS: (Laughter) This is very exciting.

Witnessing these wild fish, so full of moxie, continue their life cycle right here in our backyard is restorative. We feel a part of it.

(SOUNDBITE OF WATER FLOWING)

SAKS: For NPR News, I'm Nora Saks in Portland, Maine.

(SOUNDBITE OF LOLA YOUNG SONG, "REVOLVE AROUND YOU") Transcript provided by NPR, Copyright NPR.