Alewives are so thick it looks like the water is black. (photo by Jayne Winters)

by Roland D. Hallee

There has been much talk on the importance of the renewed alewive runs in the state of Maine. Alewives have co-evolved and co-existed with other native fish and wildlife in Maine’s streams, rivers, ponds and lakes for thousands of years. Many Mainers have never experienced an alewife run because the once thriving population has declined significantly over the last 200 years. Dams, pollution and overfishing have taken their toll.

Historians and scientists say that prior to European settling this region, there was probably not a stream flowing out of a lake or pond anywhere in the Gulf of Maine region that didn’t have an annual alewife migration, unless it was blocked by impassable waterfalls.

One history of Gardiner and Pittston written in 1852 relates that “alewives are so plentiful there at the time the country was settled, that bears, and later swine, fed on them in the water. They were crowded ashore by the thousands.”

In 1997, the Maine Department of Marine Resources began stocking alewives to a very dismal-looking Webber Pond, in Vassalboro, that was due to massive algae blooms every year. Many efforts to “clean up” the lake were implemented, but the re-introduction of alewives seemed to tip the scales toward the positive. Since the removal of the Edwards Dam, in Augusta, in 1998, the alewives can now come up the Kennebec River naturally like they had done for thousands of years into their natural spawning grounds, going as far as Sebasticook Lake, in Newport.

Togus Pond, in Augusta, was also going through the same water quality problems. Their four-year effort to re-introduce alewives finally came to fruition when 9,600 alewives were introduced into the lake. One day last summer, I witnessed what were thousands of alewife juveniles running along the eastern shore of Togus Pond.

Alewives are anadromous fish that spend the majority of their life at sea but return to freshwater to spawn.

Native American and European settlers depended on the bounty brought to inland waters by spring migrations. When one river town built a dam and blocked the fish from their spawning grounds, one early chronicler wrote that the inhabitants of the next town were outraged, sometimes approaching acts of violence.

In 1809, the selectmen in Benton ordered a dam to be torn down because it blocked huge runs of alewives and shad on the Sebasticook River.

Every May and June, adult alewives, guided by their sense of smell, migrate upstream from the ocean, and spawn in quiet backwaters or rivers and streams.

Following the spawning, adult alewives return to the ocean, leaving the juveniles behind. During the time the juveniles are in the lakes, everything within those waters eats alewives, including eels, rainbow trout, brown trout, landlocked salmon, smallmouth and largemouth bass, pickerel, pike, white and yellow perch, eagles, osprey, great blue heron, even otters, mink, fox, raccoons, skunks, weasel, fishers and turtles. See what I mean when I said everything. And that’s not even the complete list.

A female alewife can produce somewhere between 60,000 to 100,000 eggs, although only a few eggs survive to the juvenile stage. The juveniles then spend the summer and early fall months feeding on zooplankton. Come October, when the juveniles should have reached a length of six inches, they migrate downstream to the ocean where they grow to adulthood. Some males return to freshwater when they are three years old, but females will return when they are four or five years old.

It is well documented that the major factor causing algae blooms in our lakes is the introduction of phosphorus, most directly linked to residential development.

When adult alewives migrate into a freshwater pond or lake, there is an influx of phosphorus to the lake. However, the majority of the spawning alewives return to the ocean, taking phosphorus with them. In addition, young alewives that grow in freshwater will ingest phosphorus from these lakes. That phosphorus is removed from the lake when the young migrate to the ocean.

While alewives present a spectacular migration every spring that’s fascinating for people to watch, alewives perform other vital functions in the larger ecosystem. Alewives provide cover for salmon smolts that are moving down river. In the same way, alewives provide cover for upstream migrating adult salmon that could be preyed on by eagles or ospreys, and for young salmon in the estuaries and open ocean that might be captured by seals.

However, alewife populations are on a drastic decline along the eastern seaboard of the United States since the 1950s. There are several threats that have most likely contributed to their decline. These threats include loss of habitat due to decreased access to spawning areas from construction of dams and other impediments to migration, habitat degradation, fishing, and increased predation due to recovering striped bass populations.

But, if you want to witness the spring migration of thousands of alewives, visit the fish ladder located at the dam at Webber Pond, on the Webber Pond Road, in Vassalboro, and watch the alewives work their way from the stream to the lake. It is quite something to watch.

Or, you can take in the alewive festival held annually in Benton.

Roland’s trivia question of the week:

What former Boston Red Sox pitcher twice struck out 20 batters in a single game?