VOA标准英语2010年-Fish 'Cell Phones' Track Marine Life

A unique array of underwater listening devices stretches 3,000 kilometers along the west coast of North America to track marine¹ life along the continental² shelf.

"It's like giving fish a cell phone," says Pacific Ocean Shelf Tracking (POST) executive director Jim Bolger, whose network is part of a global project called the Census³ of Marine Life, an on-going effort to assess the diversity and abundance of life in the world's oceans.

Tiny transmitters

POST has strategically placed over 450 hydrophones on the sea floor.

Fish tagged with tiny transmitters emit a special signal when they pass by one of the hydrophone receivers. Rows of these small receivers form listening lines perpendicular⁴ to the shore, at intervals⁵ of about 800 meters. Bolger says the lines, which can run 50 kilometers in length, create a grid⁶ that captures fish movement across the ocean never before available.

 
VOA - E. Pfotzer
POST hopes to have listening lines deployed⁷ from shore to the edge of the continental shelf from the Bering Sea in Alaska south to Mexico.
 

"If an animal passes through one line, we hear it, and if it passes through the next line we know it's continuing and which direction it's moving in and about how fast. If it doesn't show up at the next line of receivers, either it's taken up residency in between or maybe it's died." 

Over the last six years POST has followed some 16,000 tagged marine animals, including 18 different species from salmon⁸ the size of a hotdog to great white sharks.

Bolger says a couple of times each year, POST collects the underwater data from each acoustic⁹ receiver and relays it to a ship on the surface.

Better protection for endangered species

POST recently published the first in a series of studies from its telemetry data with some unexpected findings. The endangered California sturgeon, for example, was tracked migrating north over vast distances in the winter, giving wildlife managers clues to better protect it.

 
Prince William Sound Science Center
Prince William Sound Science Center's Scott Pegau deploys¹⁰ an acoustic receiver for a new POST line in Port Gravina, Alaska.
 

Other research challenges the theory that more salmon die in dammed waterways than wild rivers. The paper compares the salmon life cycle in the heavily dammed Columbia River with that of the Fraser River in Southern British Columbia that has no dams. Bolger says the POST data showed that the survival was the same in both groups.

"And so, what does that really mean?  I think the jury is still out on that. But the fact that there is comparable survival really makes you wonder as to what are the factors that are affecting the health of these populations in both major rivers."

Bolger says the POST array can serve as a baseline for movement of various species as ocean conditions change over time in response to climate change. "We can start to really see how the animals that live in these oceans are adapting to climate changes or not adapting. And we can do a better job of sustaining the life that is here."

All POST data and research derived¹¹ from that data become part of the public record and are available for free online. Bolger says the project opens a new window on the sea and invites anyone interested in exploring the view to support the project by purchasing a radio tag and following a tagged fish on the POST Census of Marine Life website.
 

1 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

2 continental   

adj.大陆的，大陆性的，欧洲大陆的

参考例句：

• A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
• The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。

3 census   

n.(官方的)人口调查，人口普查

参考例句：

• A census of population is taken every ten years.人口普查每10年进行一次。
• The census is taken one time every four years in our country.我国每四年一次人口普查。

4 perpendicular   

adj.垂直的，直立的；n.垂直线，垂直的位置

参考例句：

• The two lines of bones are set perpendicular to one another.这两排骨头相互垂直。
• The wall is out of the perpendicular.这墙有些倾斜。

5 intervals   

n.[军事]间隔( interval的名词复数 )；间隔时间；[数学]区间；（戏剧、电影或音乐会的）幕间休息

参考例句：

• The forecast said there would be sunny intervals and showers. 预报间晴，有阵雨。
• Meetings take place at fortnightly intervals. 每两周开一次会。

6 grid   

n.高压输电线路网；地图坐标方格；格栅

参考例句：

• In this application,the carrier is used to encapsulate the grid.在这种情况下，要用载体把格栅密封起来。
• Modern gauges consist of metal foil in the form of a grid.现代应变仪则由网格形式的金属片组成。

7 deployed   

（尤指军事行动）使展开( deploy的过去式和过去分词 )； 施展； 部署； 有效地利用

参考例句：

• Tanks have been deployed all along the front line. 沿整个前线已部署了坦克。
• The artillery was deployed to bear on the fort. 火炮是对着那个碉堡部署的。

8 salmon   

n.鲑，大马哈鱼，橙红色的

参考例句：

• We saw a salmon jumping in the waterfall there.我们看见一条大马哈鱼在那边瀑布中跳跃。
• Do you have any fresh salmon in at the moment?现在有新鲜大马哈鱼卖吗？

9 acoustic   

adj.听觉的，声音的；(乐器)原声的

参考例句：

• The hall has a fine acoustic.这个大厅的传音效果很好。
• Animals use a whole rang of acoustic, visual,and chemical signals in their systems of communication.动物利用各种各样的听觉、视觉和化学信号来进行交流。

10 deploys   

（尤指军事行动）使展开( deploy的第三人称单数 )； 施展； 部署； 有效地利用

参考例句：

• It then deploys "decoy" programs designed to attract the virus. 然后，它释放“诱饵”去吸引病毒。
• But when that doesn't work, he deploys his secret defense mechanism. 但没有效果，它要施展绝密自卫武器了。

11 derived   

vi.起源；由来；衍生；导出v.得到( derive的过去式和过去分词 )；（从…中）得到获得；源于；（从…中）提取

参考例句：

• Many English words are derived from Latin and Greek. 英语很多词源出于拉丁文和希腊文。 来自《简明英汉词典》
• He derived his enthusiasm for literature from his father. 他对文学的爱好是受他父亲的影响。 来自《简明英汉词典》