古老鱼种重返伊利诺伊州水域

吴冬梅

The Illinois Department of Natural Resources is returning a fish called the alligator gar to the states rivers. Some people call the fish a “living fossil”. Experts believe the fish first appeared during the Early Cretaceous period more than 100 million years ago.

Randy Sauer is an Illinois state fisheries biologist. He says the fish disappeared from the states rivers in the 1990s， although they have continued to do well in southern states. “Biologists want to bring the fish back to northern rivers because it is important to have top predators（捕食性動物） to balance the species below them，” he said.

Sport fishermen like to try to catch the alligator gar. Alligator gars are the second?largest freshwater fish in North America. They can grow as large as 2.7 meters and weigh more than 136 kilograms. Sauer says their large size is one reason why they disappeared in the 1990s. Experts say alligator gars are“opportunistic feeders”. This means they will eat almost anything—including small turtles or ducks. They also eat invasive species such as Asian silver carp. Sauer hopes the reintroduction of the alligator gar will help the states efforts to control the carp. Because alligator gars can live up to 60 years， the program will continue to increase for many years.

Sauer notes that female alligator gars do not sexually mature until 11 years， and the male not till 6 or 7 years. That means the biologists will try to raise and release a lot of fish early in the program to reintroduce them. “Were probably going to stock （贮备） more heavily than 10 or 20 years down the road when hopefully these fish will find each other and start doing the job on their own，” Sauer says.

Small devices have been placed in 7，000 of the fish so they can be observed after they are released into the waterways of Illinois. As it rains and floods， biologists expect some of the fish will follow the rivers into the states of Louisiana and Texas.

1. Why do people call the alligator gar a “living fossil”？

A. It can grow up to 2.7 meters.

B. Its fossil can be found on earth.

C. It can grow up to 136 kilograms.

D. It has existed for over 100 million years.

2. Why will biologists reintroduce the alligator gar to northern rivers？

A. To keep the species balance.

B. To help people make more money.

C. To help to protect the environment.

D. To increase the number of the alligator gars.