450)=450">

听写填空,只写填空内容,不抄全文,4个单词/词组+1个句子,不用写标号,注意标点

In July 2011, fisheries managers from all over the world met in La Jolla, California, to discuss the state of the world's tuna stocks.

EarthSky spoke with tuna expert Bruce Collette, a senior zoologist at the Smithsonian National Museum of Natural History, to find out what makes tuna so important – and so [---1---] – among fishes.

They are among the top [---2---]. And … we fish down the food chain. We start with the biggest, most valuable species, and when that gets reduced in population, we go on to the next one, and the next one, and the next one. [---3---]

Collette said he's especially concerned about the overfishing of the species of tuna called bluefin tuna, propelled in part, he said by bluefin's high value. In Japan and Hong Kong, Dr. Collette told us, a single bluefin can fetch tens of thousands of U.S. dollars, for use in sushi and sashimi.

And the cost of these just keeps going up and up, so there is a high [---4---] for people to go out and catch them.

It's hard for bluefin tuna to [---5---] from the overfishing, Collette said, because the bluefin's life span is unusually long for fish, 15 to 30 years.
distressed predators So if you remove the top predator, you’ve disturbed the entire food chain. motivation bounce back