Snow crab legs, the commonly-seen seafood, are no longer in the restaurant.

Considering a huge fall in numbers, Alaska cancelled (取消) its Bering Sea snow crab harvest for the first time in recorded history this year. The $132 million-a-year industry saw the state’s snow crab population drop 87%, from 8 billion in 2018 to 1 billion last year. Officials suggested that climate change might be to blame; But that’s only part of the story, says Wes Jones, an Alaska-based fisheries expert. Unexpectedly, the most immediate cause of snow crab death is something even experienced fishermen didn’t see coming: they eat each other. Back in 2017, Jones says, there’s a sharp increase of young snow crabs’ population, which continued into 2019, creating the largest population on record. At the time, the young crabs were too small for a legal harvest- they take four to five years to be fully developed. Meanwhile, Bering Sea temperatures were on the rise, causing the them to speed up their metabolisms (新陈代谢)，which meant they had to eat more.” It was a double blow (打击), he says, and the results were unavoidable for the crabs lacking its usual food source: “They basically ate each other.”

Snow crabs are only the latest victims of climate change in the Bering Sea. Rising temperatures have often led to unexpected results along the food chain. A sudden increase of sockeye salmon is one possible reason for the recent sharp drop of Alaska’s red king crab harvest. Meanwhile, the warming waters of the Bering Sea have opened the door for Pacific cod, a predator (捕食者) of young crabs.

It will be years before the Alaskan snow crab population recovers to harvest-worthy levels, says Jones. And that’s only if temperatures in the Bering Sea stay cool enough for the cold-loving young crabs—and climate change is making everything harder to expect. “You don’t know what will happen until it’s happened,” says Jones, like rising water temperatures and the mutual (相互的) killings.

【小题1】Why did Alaska cancel its harvest for the Bering Sea snow crabs?

A．They were poisonous to eat at the dinner table.

B．They suffered a sharp decrease in their numbers.

C．They needed at least five years to be fully grown.

D．The fishermen wanted to sold them at higher price.

【小题2】What is the most unexpected reasons for the death of snow crabs?

A．Taking each other as food.

B．Uncontrolled heavy fishing.

C．The sharp fall in their numbers.

D．Rising temperatures of sea water.

【小题3】What does “a double blow“ refer to?

A．A lack of usual food sources and the mutual Killings.

B．A long period of growing up and a slow metabolic rate.

C．Their increase in numbers and the increased eating desire.

D．Rising temperatures in the sea and the increased predators.

【小题4】Why does the author mention ”“sockeye salmon” and “ Pacific cod”in paragraph 4?

A．To indicate the unexpected increase of these two species.

B．To direct the readers’ attention to the huge market of them.

C．To show the influence of climate change on the food chain.

D．To announce a good news brought about by climate change.