Forget Nessie: there's another insidious creature living in the waters of Scotland. The story starts in the streams and lakes of the northwestern United States, where North American signal crayfish are a familiar sight. Turn over a rock and you may well encounter one. But in Scottish streams and lochs, these creatures are intruders. American crayfish may be destroying the catch.
別去想什么尼斯湖水怪了，蘇格蘭的水域中潛伏著另一種有害生物。它們起源于美國西北部的溪流和湖泊，美國北部的人民對小龍蝦已經(jīng)見怪不怪了。翻開一塊石頭就能發(fā)現(xiàn)一只。然而在蘇格蘭，這種生物卻是入侵者，美國小龍蝦可能會毀掉蘇格蘭的生態(tài)。

Allen Pleus, with the Department of Fish and Wildlife in Washington State, says that the signal crayfish is an important species in his region. It's the only native crayfish species, and the freshwater crustaceans are just another part of the ecosystem. "They play well with others," he says. "They've learned to be good neighbors with the other native species." But those same crayfish wreak havoc in Scottish waters.
華盛頓魚類和野生動物的艾倫·普魯伊斯說小龍蝦在本地是很重要的物種。這是唯一的本地小龍蝦種，而淡水甲殼動物是生態(tài)系統(tǒng)的另一部分。“它們彼此相處得很好，和其他本地物種也相處融洽?！钡峭N的小龍蝦卻在蘇格蘭肆虐。

Matt Mitchell has been casting his line into these waters for about 40 years. "This area is probably, if not the best, certainly one of the best trout fisheries in the world," he says. One day Mitchell got a call from an angler friend. The conversation changed Mitchell's life. "I could not believe the number of crayfish that were in this part of the river. You could literally walk across the river standing on crayfish!"
麥特·米歇爾在這片水域作業(yè)有40年了?！拔覀冞@有世界上數(shù)一數(shù)二的鱒魚，”他說。然而有一天他接到了來自釣友的電話，而這個通話改變了他的一切?！拔液喼睙o法相信這里有多少小龍蝦。你甚至都能踩著它們過河！

The North American signal crayfish, which had been introduced to English waters decades ago and spread steadily north, were taking over. "They were big animals. I mean, some of these things were about 10, 12 inches long." At that size, they don't even look like crayfish; they look like lobsters. Animals that big, Mitchell says, are more than a decade old; he guesses they've been in the river for 12 years.
北美標(biāo)志性的小龍蝦是在數(shù)十年前被引入英國境內(nèi)，并且向北蔓延最后占據(jù)了水域?！八鼈儗?shí)在是很大，有一些都能長到10、12英寸?！庇兄@樣的尺寸，它們甚至看起來不像小龍蝦更像大龍蝦。米歇爾說，這么大的動物起碼有十歲以上，他認(rèn)為這些至少是十二年的小龍蝦。

The problem isn't just the size or quantity of the intruders; it's that the signal crayfish eat the same insects and larvae as the prize-winning trout that are native to these streams.?Mitchell's colleague Ian Miller is the man who first placed that concerned phone call from the Clyde Burn all those years ago. With the arrival of the crayfish, Miller says, "Stoneflies are gone — basically wiped off the face of the Earth." That's a problem, because stoneflies are an important food for the fish. No?trout?food means no trout.
問題不是只在于這些入侵者的尺寸或者數(shù)量，而是這些小龍蝦會吃掉同樣生活在這片水域的鱒魚賴以為生的浮游生物。米歇爾的同事伊恩·米勒是很多年前就第一個認(rèn)識到這個問題的人。米勒說，小龍蝦的到來使得“石蠅消失了，基本上就是滅絕了。”這是問題所在，因?yàn)槭壥囚~類重要的食物來源。沒有食物，就沒有鱒魚。

Turns out, Washington State is struggling with a similar problem. "Unfortunately, we now have our own invasive-species crayfish in this area — mostly red swamp crayfish from the southern United States," he says. That's right. At the same time that the North American signal crayfish are taking over rivers and streams in Scotland, they're being crowded out of rivers and streams in their native habitat byother invasive crayfish?— interlopers from Louisiana.
實(shí)際上，華盛頓也面臨著同樣的問題?！昂懿恍遥覀冞@也來了一群不速之客，大多數(shù)是來自美國南部的紅沼澤螯蝦。事實(shí)也如此，當(dāng)蘇格蘭的江河溪流被美國北部的小龍蝦侵略時，來自路易斯安那州的小龍蝦也占領(lǐng)了華盛頓的地盤。