Bahan Presentasi : File PPT
Reading A pair work Discuss these questions. Then read article, and check your answers.
- What do you think the title of the article means?
- What is a fish farm?
- What is the meaning of trangenics?
- I think the title of the article is Seafood that never sees of the sea.
- A fish farm is the man is work find of seafood the sea.
- Trangenics is the transfer of genes from one species to another.
lthough 80% of the world’s seafood comes from marine harvests, there is a major shift under way toward aquaculture now. Nearly 40% of salmon marketed today is raised in captivity, compared with 6% a decade ago. Forty percent of all calm, oysters, and mussels are produced infarm environments, along with 65% of freshwater fish. “the fact that world seafood supplies continue to increase at all is due almost entireliy to the phenomenal growth in aquaculture, “says Anne Plat McGinn, a research associate at the Worldwatch Institute.
Biotechnology is contributing to high – yield aquaculture through transgenics – the transfer of genes from one species to another. Researchers introduce desirable genetic traits into fish, creting hardier stocks. For example, some species of fish have a protein that allows them to live in Arctic waters. By transplanting this “anti – freeze” gene into other species, researchers have created more fish that can survive in extremely cold water. Biotechnologists are attempeting to improve a wide range of genetic traits in fish used for aquaculture, developing fish that are larger and faster – growing, more efficient in converting feed into muscle, more tolerant of low oxygen levels in water, and better able to resist disease.
While aquaculture produces a reliable source of potein, the industry is rife with environmental problems, asserts McGinn. Perhaps the biggest concern is water pollution : Fish waste and uneaten food accumulate at farm sites and can float directly downstream into water supplies. McGinn charegers that aquaculture also uses resources inefficiently. Fish farms need protein feed, and about 17% of ocean fish, an overharvested wild resource, becomes food for captive – bred fish. “An estimated five kilograms of oceanic fish reduced into fish meal are required to raise one kilogram of farmed ocean fish or shrimp, representing a large net protein loss,” says McGinn.
Fish farming does not have to be an inefficient or polluting industry. McGinn predicts that many consumers will choose sustainably produced fish in the future, just as they prefer dolphin – free tuna today