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Science & Technology
科技版塊
Marine conservation
保護海洋環境
A green light for saving sharks
拯救鯊魚的綠光
Illuminating fishing nets may reduce by-catch
發光的漁網會減少捕獲量
Small-scale fisheries supply many people with food.
小型漁業為許多人提供食物。
Almost all of those who ply them rely on gillnets to trap their prey.
幾乎所有捕食者都依靠刺網誘捕獵物。
But gillnets trap other things, besides: endangered animals such as turtles; dangerous ones, such as Humboldt squid; and ones that are both endangered and dangerous, such as several types of shark.
但是刺網還能捕捉其他東西，比如瀕危動物——海龜；危險的，如洪堡烏賊；還有既瀕危又危險的物種，比如幾種鯊魚。
Everyone involved would be better off if this did not happen.
如果這種情況不發生，參與其中的每個人都會過得更好。
Building on studies done both by himself and by others, to try to avoid the accidental netting of turtles, Jesse Senko, a marine-conservation biologist at Arizona State University, has been investigating the idea of fitting light-emitting diodes (leds) to nets to ward off other unwanted by-catch without discouraging target animals from entangling themselves.
亞利桑那州立大學(Arizona State University)的海洋保護生物學家杰西·森科(Jesse Senko)在自己和其他人所做研究的基礎上，試圖避免意外捕獲海龜，他一直在研究將發光二極管安裝到漁網上的想法，可以纏住目標獵物的同時又能避開其他不想要的獵物。
And, as he reports in Current Biology, it seems to work.
而且，正如他在《當代生物學》上所報道的那樣，這似乎奏效了。
His particular concern was for the safety of elasmobranchs, as sharks, rays and skates are called collectively.
他特別擔心的是板鰓魚的安全，板鰓魚是鯊魚、魟魚和鰩魚的統稱。
While sharks are better known for their sensitive nostrils than their keen eyesight—some species famously being able to smell traces of blood in vast quantities of water—many have acute vision, too.
與敏銳的視力相比，鯊魚更為人所知的是它們靈敏的鼻孔，——一些鯊魚以能夠在大量水中聞到血跡而聞名，不過許多鯊魚也有敏銳的視力。
And, though colloquially referred to as "fish", elasmobranchs are actually less closely related to teleosts (the bony fish that predominate on most fishmongers’ slabs) than turtles are, so their visual systems might easily be as different.
雖然俗稱為“魚”，但板鰓魚與硬骨魚（硬骨魚在大多數魚販的魚板上占多數）的親緣關系實際上不如海龜，所以它們的視覺系統很可能與海龜一樣不同。
It thus seemed worthwhile checking to see whether the trick that worked with turtles would work with sharks.
因此，似乎值得試一試，看看對海龜有效的方法是否對鯊魚也有效。
Dr Senko and his colleagues therefore set up an experiment in the Gulf of Ulloa, off the coast of Baja California, in Mexico, in which they collaborated with local fisherfolk to deploy over 10,000 metres of nets that had had battery-powered waterproof green leds clipped onto them at ten metre intervals.
因此，森科博士和他的同事們在墨西哥加利福尼亞州海岸外的烏洛亞灣進行了一項實驗，他們與當地漁民合作，部署了超過1萬米的漁網，這些漁網上每隔10米就夾著電池供電的防水綠色發光二極管。
(Green leds are more efficient than those of other colours, and their light better penetrates seawater.)
（綠色發光二極管比其他顏色的發光二極管效率更高，而且它們的光更能穿透海水。）
In half of the nets these lights were illuminated.
漁網中的二極管，一半被照亮。
The other half were left unlit, as controls.
另一半作為對照，沒有點亮。
Each lit net was paired with an unlit one, and the two were deployed alongside one another at prime fishing locations.
每個發光的網與一個不發光的網作對照，這兩個網并排部署在主要的捕魚地點。
The fishers' targets were Californian halibut and large groupers.
漁民的目標是加利福尼亞的大比目魚和大型石斑魚。
Dr Senko was interested both in what else got caught and whether the lights decreased catches of the target species.
森科博士感興趣的是除此之外還捕捉到了什么，以及燈光是否減少了對目標物種的捕獲量。
On the latter point, reassuringly, they did not.
在后一點上，令人放心的是，并沒有減少捕獲量。
On the former, the lit nets caught 95% fewer kilograms of sharks, rays and skates.
關于前者，點燃的漁網捕獲的鯊魚、魟魚和鰩魚數量減少了95%。
In particular, several threatened species, including Munk’s devil ray (pictured) and the diamond stingray, turned up less often in the illuminated than the unilluminated nets.
特別值得一提的是一些瀕危物種，包括芒克魔鬼魚和鉆石黃貂魚，在有照明的漁網中出現的頻率低于沒有照明的漁網。
Humboldt squid were also discouraged.
洪堡烏賊出現的頻率也低了。
(Cephalopods, the group of molluscs to which they belong, are also well known for their acute eyesight.)
（頭足類是軟體動物的一種，它們也以敏銳的視力而聞名。）
The advantage from the point of view of fisherfolk was that they needed to spend a lot less time clearing these hostile by-catches from their nets.
從漁民的角度來看，這樣做的好處是，他們可以花更少的時間從漁網中清除這些有害的副漁獲物。
And, crucially, the leds concerned are cheap, robust and easy to fit.
而且至關重要的是，用到的發光二極管價格便宜，堅固耐用，易于安裝。
There are also plans to make them solar powered, for easy recharging.
為了方便充電，還計劃讓它們使用太陽能。
Here, then, is a conservation idea from which everyone wins.
這就是一個人人都能從中受益的環保理念。
