It was just this past week, on Tuesday, that the shadblow serviceberries around Eastport signaled the true arrival of spring, the loosening of winter’s grip on their pointed buds. When I return to Maine at the end of spring break, roadsides from Cape Elizabeth to Eastport will be adorned with these small multistemmed trees in full bloom, bright white clouds come to earth.

Each April, when I see these trees festooned with their delicate white flowers, I try to imagine how it was to live in Maine when the blooming of Amelanchier canadensis, the shadblow serviceberry or shad bush, signaled spawning runs of alewives in the Penobscot, Dennys, Pleasant and other Maine rivers, streams and ponds.

Of all the migratory fish that came up Maine’s rivers, the alewife, close relative of the American shad, was the most abundant. One historical account, written in 1852, relates that alewives were once so plentiful in Maine streams “that bears, and later swine, fed on them in the water. They were crowded ashore by the thousands.” Cheryl Daigle, community liaison and outreach coordinator for the Penobscot River Restoration Trust, tells me that alewives were once so common that Maine farmers used them to fertilize their fields.

The alewife fishery in Maine is four centuries old. In the beginning, the bulk of the harvest was for human consumption; alewives provided a critical source of fresh food at a time of year when winter food supplies were low. Even today, Maine law requires towns to supply widows and orphans with 2 free bushels of herring if they ask.

Lobster fishermen prefer to use alewives as bait, when they can get them. In the past, the alewife harvest provided 30 percent to 50 percent of the bait used during the spring. With decreased returns of adult alewives in recent years, only about 1 percent of lobstermen’s bait needs can be filled with alewives.

Although alewife populations have plummeted during the past two centuries due to dam construction, pollution and over-harvesting, spawning runs still occur. Each spring, when the shadblow serviceberries are in full flower, the adult alewives, guided by their sense of smell, migrate upstream from the ocean to rivers, streams, ponds and lakes. While a single female alewife produces 60,000 to 100,000 eggs, only a few survive to the juvenile stage, and sometimes only as few as three juveniles survive to adulthood. Some adults die after spawning, but the majority make their way back to the ocean shortly after spawning – and many return the next spring to spawn again.

I think about all of this when I see the shadblow in bloom, about how the phenological event of a tree’s flowering carried such weight in the lives of past generations and gave this beautiful native tree its common name. If efforts to restore the Penobscot and other Maine rivers are successful, perhaps the sight of shadblow in bloom will once again send us scampering to the nearest shore to watch alewives in their spawning frenzy, to see ospreys and eagles taking their share, to eat smoked alewife, and feel connected to the past.

Write to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to rmanley@ptc-me.net. Include name, address and phone number.