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Fieldwork May Aid State Shad Restoration
Story posted July 22, 2005
It's just a scant few fish eggs, translucent and barely visible in the waning afternoon light. But to Mark Burton '07, it might as well be gold.
It is the first positive proof that the American shad is indeed spawning in these waters, which are located downstream from the Brunswick Hydroelectric Dam. Marine biologists have suspected a shad spawning ground was located somewhere along this stretch of the Androscoggin River since shad began returning to these once heavily polluted waters a decade ago.
"I kind of thought they'd be here," says Jaret Reblin, a Bowdoin laboratory instructor who is assisting Burton in this fieldwork. "This stretch of river seems to be the right habitat, with a cobbly, sandy bottom."
It's only a small sample, but it is encouraging.
Assistant Professor John Lichter is overseeing their research effort, which is part of a larger, ongoing ecological examination of Merrymeeting Bay. "Most of this research has focused on the flora of the Merrymeeting Bay ecosystem," he says, "This is the first time we are incorporating animal-ecology studies. Our early data are good news."
The findings will be of special interest to the Maine Department of Marine Resources (DMR), which has been radio-tagging and monitoring fish at the Brunswick Dam. The dam is the site of a vertical slot fishway, or fish ladder, which is designed to help anadromous fish to get upstream to spawn.
Shad were once hugely abundant in these waters, as were their brethren the Atlantic salmon, striped bass, alewife and sturgeon. Years of heavy industrial pollution - much of it from paper mills upstream -- all but wiped out many of these anadromous species, which migrate from sea to freshwater to spawn.
A tepid restoration of some populations is following cleanup efforts, but their numbers are nowhere close to what they were a century ago.
"Beginning in 1995, we started seeing remnants of a shad population increasing below the dam," says Michael Brown, a marine scientist with the DMR. "We were encouraged, but also discouraged, because the shad wouldn't negotiate to the top of the fishway in appreciable numbers. Only 12 made it through last year."
Brown says the fish ladder's design - which was modeled somewhat unsuccessfully after fishways in the Pacific Northwest - isn't proportioned well for the shad, though other species do well with it.
"We suspected that those fish that didn't make it up the ladder would spawn lower down the river," says Brown, "but we didn't have the manpower to spend the time necessary to monitor that. That's where John Lichter came in: He said he would like to have one of his students do a project related to fish on the Androscoggin that would provide us with some data to fill some voids."
Lichter took on the research project, recruiting Burton and Reblin for fieldwork. Burton, who hopes to make a career in field biology, says the project is "perfect."
"It's field work, I love to be outside, and I'm on the coast of Maine all summer," he says. "And it's incredibly beautiful to be out in a boat at 5:30 a.m. on the Androscoggin with no one else on the water."
The pair has been setting a large net along the river channel for several weeks, hoping to turn up shad eggs. The eggs are small - only two millimeters in diameter - so identification is difficult. Much of what they catch, says Burton, is submerged aquatic vegetation. "Tidal grasses, terrestrial vegetation. You also get quite a number of insects -- some of them are really cool-looking."
The samples are funneled into a cup and taken back to Lichter's lab, where Burton logs information about the day's netting into a database. So far, in 15 nettings, Burton has only positively identified one group of eggs, but he is hopeful they will get more samples soon.
"Recently there was very little current on the river," notes Burton, "so the eggs - which are bounding on the bottom - weren't flowing into the net. Also, the spring was so cold that it delayed the shad run, so we're hoping in the next couple of weeks we'll get something."
The window on the season may be closing soon, however, notes Lichter. "July is their spawning season," he says, "they stop in August. It may be very hit or miss for the rest of the project. But the good news is that we did find some eggs."
If he can gather the data to support it, Lichter hopes to develop a GIS map of the lower Androscoggin indicating specific areas where shad indeed are spawning - as well as the nursery habitat where juvenile fish find forage and safety from predators before returning to the sea.
Even without the map, DMR's Michael Brown says the current research is "very helpful."
"It does confirm that shad are spawning in the river," he says, "and in the bigger picture, it will help us protect any spawning areas if there are projects planned that may impact these spawning areas. We see John and his student's work really helping out on the shad restoration on the Androscoggin River."
Mark Burton's research fellowship is supported by the Henry L. and Grace Doherty Charitable Foundation Coastal Studies Research Fund.
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