亚洲免费av电影一区二区三区,日韩爱爱视频,51精品视频一区二区三区,91视频爱爱,日韩欧美在线播放视频,中文字幕少妇AV,亚洲电影中文字幕,久久久久亚洲av成人网址,久久综合视频网站,国产在线不卡免费播放

        ?

        古老魚種重返伊利諾伊州水域

        2020-12-29 12:04吳冬梅
        瘋狂英語·愛英語 2020年12期
        關(guān)鍵詞:伊利諾伊州魚種水域

        吳冬梅

        The Illinois Department of Natural Resources is returning a fish called the alligator gar to the states rivers. Some people call the fish a “l(fā)iving 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 (貯備) 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 “l(fā)iving 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.

        猜你喜歡
        伊利諾伊州魚種水域
        我來講故事
        美伊利諾伊州強(qiáng)制要求公立學(xué)校講授亞裔歷史
        江蘇:出臺辦法 對五類重要水域?qū)嵭刑貏e保護(hù)
        魚種優(yōu)劣鑒別方法
        冬放魚種技術(shù)
        美國伊利諾伊州學(xué)術(shù)圖書館聯(lián)盟研究
        魚種深秋管理四要點(diǎn)
        人妻少妇精品无码专区动漫| 亚洲欧美国产精品久久久| 日本a在线天堂| 亚洲一区极品美女写真在线看| 亚洲天堂线上免费av| 日本av在线一区二区| 国产精品99无码一区二区| 激情 人妻 制服 丝袜| 人妻少妇精品无码专区二| 亚洲va成无码人在线观看| 国产精品区二区东京在线| av网站大全免费在线观看| 特黄做受又粗又长又大又硬| 亚洲另类激情综合偷自拍图| 2021国产精品久久| 久久综合激激的五月天| 亚洲美女毛多水多免费视频| 天天爽夜夜爱| 比比资源先锋影音网| 国产人澡人澡澡澡人碰视频| 国产精品麻豆成人av| 亚洲精品国产成人久久av| 国产成人精品久久一区二区三区| 国产99久久亚洲综合精品| 欧美国产日本精品一区二区三区| 日本视频精品一区二区| 国产亚洲精品在线播放| 国产av国片精品jk制服| 日韩成人无码一区二区三区| 一区二区三区在线视频免费观看| 国产精品熟女一区二区三区| 男女后进式猛烈xx00动态图片| 国产精品99久久免费| 91亚洲欧洲日产国码精品| 成a人片亚洲日本久久| 一区二区三区视频在线观看免费| 亚洲av无码av在线播放| 一本之道高清无码视频| 国产精品视频一区二区三区,| 精品国产一区二区三区av新片| 久久精品国产亚洲超碰av|