Monday, June 21, 2010

Presumpscot Falls Blueback Herring and American Shad, Portland, Maine.

This is the second in a two-film series by Douglas Watts providing the first underwater videos of the native migratory fish of the Presumpscot River, Maine. Part one is here. This project is funded by members of Friends of Sebago Lake.

The focus of this second film is Presumpscot Falls, at the river's head of tide in Falmouth and Portland, Maine, and the spring return of native blueback herring and American shad to spawn in the river above the falls. The opening segments show the natural environs just above the falls, including a small spring brook and the wide variety of native wildflowers which dot the mature forest in the valley of the river. The falls is approached from the upstream side as if you were an unlucky canoeist caught in the torrent. Queequeg T. Dog, Ph.D. provides size perspective and aesthetic counsel.

A blueback herring and shad's eye view of Presumpscot Falls.

At the time of filming, in early June, the blueback herring and American shad runs were nearing their peak and the fish congregated at the deep plunge pool at the base of the falls by the thousands as they struggled to swim through the heavy water to their upstream spawning grounds.

The underwater filming was done with a small waterproof video camera attached to a long, metal broom handle with multiple hand straps and duct tape. The camera position was obtained by swimming out to a large mid-river rock, and repeatedly plunging the camera and broom stick deep into the water when a school of fish appeared close by. Because the current is so strong at the base of the falls, it was nearly impossible to keep the camera steady for more than a few seconds. Also, because the fish were quickly spooked by a long broomstick waving in their midst, each filming attempt was limited to a couple quick plunges before the herring and shad dispersed. Then it was a matter of waiting for them to regather and hoping the sun did not duck behind any clouds. It took two afternoons of filming to get the underwater footage here.
Blueback herring leaping the rapids at Ticonic Falls, Kennebec River, Waterville, Maine. Photograph by Tim Watts.
River bottom view of blueback herring getting ready to tackle the ledge drops at Ticonic Falls, Kennebec River, Waterville, Maine. Photograph by Tim Watts.

The dominant species in the footage is the blueback herring (Alosa aestivalis). Bluebacks are closely related to the alewife, which is also native to the Presumpscot, but alewives migrate upstream several weeks earlier in the spring than bluebacks. Like alewives, bluebacks are born in freshwater but live in the ocean. After one summer in freshwater as babies, they migrate to the ocean and live and grow for 3-4 years before returning to their home river to spawn. Unlike alewives, which spawn in freshwater ponds, blueback herring spawn in the river itself. Blueback herring are slightly smaller than alewives, with an average length of about 9-10 inches. Blueback herring are an important food source for fish-eating birds such as great blue heron, osprey and cormorants as well as striped bass. They are an essential food source for osprey nestlings. During the peak of the blueback run, the rapids and bedrock gorge of Presumpscot Falls are a circus of bird and fish life as osprey wheel about diving for herring, great blue heron spear them from streamside rocks and large striped bass attack them from below.

This still image from Presumpscot Falls shows the size difference between American shad and blueback herring. The American shad is the very large fish in the top of the image. It is probably 24-26 inches. The 9-10 inch blueback herring are directly below. A second, smaller shad is visible at right in the background.

The June 2009 filming revealed a much larger population of American shad in the Presumpscot than previously thought. American shad (Alosa sapidissima) are closely related to alewives and bluebacks but can reach nearly 30 inches long and 10 pounds, with an average size of about 24 inches and 3-5 pounds. Shad migrate upriver in June and spawn in deep holes in the river in July. The young migrate to sea in the fall at a length of 3-4 inches. Unlike their smaller cousins, shad spend 5 to 6 years in the ocean before returning to their river of birth to spawn.

During the two afternoons of filming in early June, schools of 30 or more large shad could be sometimes seen rushing to the surface in the center of the channel, always surrounded by much larger groups of blueback herring. Shad are extremely wary and prefer deep water away from shore. They only rose close to the surface when preparing to mount their attack on the nearly vertical drop of the falls. But during these brief, but repeated observation windows, it was obvious that the total number of shad present at the base of the falls was in the hundreds. Filming the shad was very difficult because they tended to stay out of underwater camera range and the camera's view was usually blocked by the bodies of blueback herring. Despite the excellent clarity of the Presumpscot during filming (it hadn't rained for a week), the natural light dispersal of the river water and the turbulence and bubbles of the plunge pool required the fish to be within a couple feet of the camera to be visible.

This little movie and its cousin are but weak tea compared to going to Presumpscot Falls yourself.

Music Credits:

"Monk's Apple": Patrick Malia, solo piano. Written by Patrick Malia.
"Tispaquin's Revenge": Jason Rowland, drums. Ted St. Pierre, bass. Patrick Malia, guitar solo. Douglas Watts, keyboards, guitar, percussion. Written by Douglas Watts.
"Rose Reprise": Conni St. Pierre, keyboards and flutes. Written by Conni St. Pierre.
All selections recorded at the Outlook, Bethel, Maine, engineered by Ted St. Pierre.

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