信天翁打击非法捕鱼

Albatrosses

如果你坐过渔船,一定常见鸟群尾随其后,想捡零食吃。现在科学家说,他们可以利用这些海鸟打击非法捕鱼。原理是这样,研究人员在南大洋和印度洋上空一百六十九只信天翁的背上绑定了信息记录仪,记录仪只有一点五磅重,却包含了全球定位系统,可以检测渔船上发出的雷达信号,以及信号的强度。这些信息通过卫星传输给研究人员,研究人员对海鸟和发信号的渔船进行实时追踪。

每艘渔船都有一套报送行踪的系统,这套系统又叫船舶自动身份识别系统。科学家于是将海鸟发回的信息与官方的渔船信息进行比对,结果发现信息不一致的情况经常出现。有不止三分之一的时候,海鸟检测到了渔船的雷达信号,但官方信息系统却显示没有该船只,这也就意味着渔船很可能关闭了自动身份识别系统。研究人员说,关系统的做法往往发生在非法捕鱼行动中。这项研究发表在美国国家科学院论文集上。

这项研究表明,海鸟或是监控渔船的有效工具,只要非法捕鱼的渔民找不到那只安了监控的鸟。好在找到那只鸟并非易事,数百只鸟围着渔船飞,百里挑一谈何容易。何况安了监控的鸟不带任何标记,渔民不好分辨。这项研究的作者是利物浦大学的海洋生物学家萨曼莎。

萨曼莎更担心的是,信天翁经常被渔网网住。尽管有明文规定不得用渔网捕捉信天翁,这种保护措施也取得了一定成效,但非法捕鱼的渔船不一定遵守。所以说科学家们还是低估了信天翁所面临的风险。不论如何,这套系统让渔船受到了严密监视,今后非法捕鱼的日子不会那么好过了。

原文

If you’ve ever been on a fishing boat, you’ve probably seen flocks of birds following in your wake, hoping to catch a snack. Now scientists say they can use those birds’ behavior to track illegal fishing boats. Here’s how it works: Researchers attached data loggers to the backs of 169 albatrosses in the Southern and Indian oceans. The devices weighed only an ounce and a half, but they included a GPS—which enabled them to detect the presence and intensity of radar signals emanating from boats. That information was then transmitted by satellite, so the researchers could track the location of the birds—and thus the radar-emitting boats—in real time.

The scientists then cross-checked that data against the known locations of boats, gleaned from a system boats use to declare themselves, called the Automatic Identification System. And discrepancies appeared frequently. More than a third of the times the birds’ loggers’ detected radar signals, and therefore a boat, no such boat appeared in the official log—meaning that the vehicles had likely switched off their Automatic Identification Systems—something the researchers say probably happens in illegal fishing operations. The results are in the Proceedings of the National Academy of Sciences.

The work suggests birds could be an effective boat-monitoring tool—as long as illegal fishing operations don’t target the birds, that is. Fortunately, such a task would be difficult. “Around fishing vessels, you can get hundreds of birds at any one time that are all flying around. So it’s not really possible to target a specific bird. And the birds with loggers on are not marked in any way. So it’s difficult for fishermen to pick out a specific bird.” Study author Samantha Patrick, a marine biologist at the University of Liverpool.

Patrick’s bigger concern is that albatrosses often get hooked on fishing lines. And though regulations have been established to protect against that happening—with success—illegal boats don’t necessarily comply. So scientists might be underestimating the risk posed to albatross populations. But this system could mean that those illegal boats may have a tougher time flying under the radar.

发表评论