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This summer, Patrick Millet ’14 of Haiti has been getting up-close and personal with American eels in Maine. Working under Professor of Biology and Environmental Studies John Lichter (with funding from the Sustainability Solutions Initiative), Millet is exploring the connection between eel populations and underwater plant cover, in hopes of advancing eel conservation.
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Each morning Millet and his research team grab their gear from Druckenmiller Hall and motor out into Merrymeeting Bay, one of only four estuaries in the world that’s shared by multiple rivers. A historically productive ecosystem, the bay suffered the effects of pollution and damming during the industrialization era, but has been on the mend since the 1970s.
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Millet’s study subject is a nocturnal carnivorous fish that spends most of its life in fresh water. Upon reaching adulthood, it heads into the ocean to spawn. Though American eels support a profitable fishery in Maine, their numbers have dropped because of factors such as dam construction (blocking their passage to and from spawning grounds) and overfishing.
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Pondweed, pictured here, is one of the dominant aquatic plant species. Submerged vegetation provides benefits such as shelter for eels and their prey. One thing Millet wants to know is whether sites with more vegetation are home to more eels.
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Millet baits each trap with a couple of river herring and places it on the estuary bottom, returning 24 hours later to see how many eels he has caught.
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Some trap locations have little or no vegetation, while others are filled with dense mats of pondweed and other plants (historically, the bay probably had more submerged vegetation overall than it does today).
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One of Millet’s study sites is Butler’s Cove, on the on the eastern side of Merrymeeting Bay. Millet also puts traps in Abagadasset Point, on the western shore, to get a picture of eel dynamics on both sides of the estuary.
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Though Millet’s project has been in progress for only a few weeks, he has already trapped several dozen eels at each site. Unofficially, his initial results seem to support the hypothesis that more vegetation means more eels.
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Millet measures each eel he traps, to see if eel size is linked to the amount of vegetation in a site (so far, it doesn’t appear to be related). Adult eels max out at just under four feet long.
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Assistant eel-wrangler Nate Niles ’14 releases an eel back into the bay. Niles is working on a project of his own with Professor Lichter, to determine whether a fish lift is a viable option for helping American shad scale the Brunswick Hydroelectric Dam.
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In addition to assisting Millet and Niles (right) with eel and shad research, fellow scientists Teresa Withee ’15 (left) and Elizabeth Brown ’14 (center) are working on a project to transplant eelgrass back into the bay.
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Millet hopes that learning more about the role of vegetation will help clarify conservation priorities for the American eel. “Eels could bounce back, because they’re some of the most prolific fish out there,” Millet said. “However, you’d need to restore their freshwater ecosystem so that the adults can live.”
See more stories about the summer adventures of Bowdoin students around the world on our #BowdoinMap.
