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(单词翻译:双击或拖选)
If you ever get a chance to meet a sea lamprey, you won't forget it.
They look like an eel1 but they're actually a fish. They have a suction cup for a face, with hundreds of razor sharp teeth.
"And they will sucker onto a fish and actually rasp a hole through the fish's skin and scales and actually feed off the blood and body fluids of the host fish," says Aaron Jubar. He's with the U.S. Fish and Wildlife Service in Ludington.
A threat to the lakes
Sea lampreys devastated2 the Great Lakes fishery in the middle of the last century, and we're still battling them today.
"We estimate a single sea lamprey in the Great Lakes can destroy up to 40 pounds of Great Lakes fish through its parasitic3 life which is only about 18 months," Jubar says.
They love to feed on lake trout4, salmon5, whitefish and steelhead - the prize fish at the top of the food web in the Great Lakes.
We spend more than $28 million in federal money each year to control the lampreys (according to the Great Lakes Fishery Commission, $20.9 million goes to sea lamprey control measures and more than $3 million is spent on sea lamprey research). A big part of that control program is finding out where the lampreys hide out when they're little.
On the day I join Aaron Jubar and his team to go lamprey hunting in the Clinton River in Macomb County, they're wearing waders and gloves and they have metal contraptions strapped7 to their backs. They look like Ghostbusters.
"What we're using today is our backpack electro-fishing units and these are specially8 designed to capture sea lamprey larvae9," Jubar says.
The backpacks send an electric current down through two metal probes. The crew members move these through the water looking for lampreys.
"And then that low pulse agitates10 them so they come shooting out of their burrows11 and when we see them, then we can high pulse and that actually completely immobilizes them and then we can scoop12 them up," he says.
I'm in waders so I can get in the river too, but Jubar warns me not to touch the water.
"You would definitely feel it, the low pulse would be a sharp tingling13; the high pulse, you'd feel that shoot up your arm," he says.
The continuous fight
Jason Krebill is stirring up the muck at the bottom of the Clinton River.
"Looks like I got a crayfish," he says.
He's been chasing lamprey larvae for 15 years now.
"Yeah, they're ugly, but in the same regard, functionally14, they're kind of beautiful, you know?" he says. "As far as parasites15 go, they've pretty much got it down. They get a free meal and a free ride for the majority of their life. I think they sacrifice looks for smarts."
The U.S. lamprey hunting teams do 2,000 of these surveys all over the Great Lakes region every summer. And there are more of these teams on the Canadian side. They're trying to find out where the lampreys are. If they find them, different crews come out and kill the lampreys with a lampricide.
Jubar says they're constantly trying to knock back their numbers. It's a battle that's been going on since the late 1950's.
"They're a lot like cockroaches," he says. "You leave two behind, you have a problem, because the females can have up to 100,000 eggs. So just one female and one male can infest16 this whole stream potentially."
He says they're keeping the sea lampreys in check in most of the Great Lakes. But in the past six years, lampreys have been booming in Lake Erie. In 2009, Jubar says they estimated there were about 30,000 sea lampreys in the lake.
"In 2014, we estimated just over 14,000 sea lampreys in Lake Erie so, we're still five times above our target levels," he says.
He says the St. Clair River is probably a big part of this puzzle. Jubar says they estimate there are more than 900,000 baby lampreys in that river.
He says as the St. Clair and Detroit Rivers have gotten cleaner, they've become better habitat for lampreys.
In addition, he says the lake trout and steelhead fisheries are doing very well in the eastern basin of Lake Erie, so there's more of the lampreys' favorite food available.
We turn up empty handed on this lamprey hunt. But Jubar says that's actually a good thing.
"We've never found them up this far, but we are very vigilant," he says.
And they'll keep doing this work, every single summer, to try to stay on top of this expensive, blood-sucking parasite.
收听单词发音 |
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eel
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| n.鳗鲡 | |
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devastated
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| v.彻底破坏( devastate的过去式和过去分词)；摧毁；毁灭；在感情上（精神上、财务上等）压垮adj.毁坏的；极为震惊的 | |
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parasitic
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| adj.寄生的 | |
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trout
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| n.鳟鱼；鲑鱼(属) | |
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salmon
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| n.鲑，大马哈鱼，橙红色的 | |
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parasite
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| n.寄生虫；寄生菌；食客 | |
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strapped
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| adj.用皮带捆住的，用皮带装饰的；身无分文的；缺钱；手头紧v.用皮带捆扎(strap的过去式和过去分词)；用皮带抽打；包扎；给…打绷带 | |
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specially
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| adv.特定地；特殊地；明确地 | |
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larvae
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| n.幼虫 | |
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agitates
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| 搅动( agitate的第三人称单数 )； 激怒； 使焦虑不安； （尤指为法律、社会状况的改变而）激烈争论 | |
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burrows
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| n.地洞( burrow的名词复数 )v.挖掘（洞穴），挖洞( burrow的第三人称单数 )；翻寻 | |
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scoop
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| n.铲子，舀取，独家新闻；v.汲取，舀取，抢先登出 | |
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tingling
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| v.有刺痛感( tingle的现在分词 ) | |
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functionally
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| adv.机能上地，官能地 | |
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parasites
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| 寄生物( parasite的名词复数 )； 靠他人为生的人； 诸虫 | |
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infest
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| v.大批出没于；侵扰；寄生于 | |
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