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    FancyEnglish            Sharks at Risk              百科知识

       October 28, 2011

　

(CNN Student News) -- October 28, 2011 Sharks at Risk AZUZ: So lions, tigers, sharks, those are examples of apex predators. But it turns out shark populations are actually decreasing. And when you take away an apex predator, it can have serious consequences for the rest of that food chain. Kaj Larsen looks at some of the potential ripple effects and explains why the ocean`s top predators have become prey. (BEGIN VIDEO CLIP) KAJ LARSEN, CNN REPORTER (voice-over): Shark populations are crashing around the world. Millions die by finning to feed the growing demand for sharkfin soup in Asia. Roughly a third of all shark and ray species face some threat of extinction. Without them, the marine food web could start to unravel. Marine biologist Luke Tipple is on a mission to protect sharks. We met up in the Bahamas. LUKE TIPPLE, MARINE BIOLOGIST: Actually, the marina that we`re in right now was one of the first shark-free marinas in Bahamas. LARSEN (voice-over): Sharks are an apex predator, which means they`re at the very top of the marine food chain. They grow slowly, mature late and produce few young, making them vulnerable to overfishing. TIPPLE: We`re supposed to have a number of sharks to able to control all of these animals which are below them. So what we do is we take out that apex and we allow a lot of other fish to breed underneath them. They basically annihilate everything below them, and that leads to trophic collapse, which means we don`t have healthy ocean systems, and we won`t be able to pull food or product from there anymore. LARSEN (voice-over): The Bahamas banned commercial shark fishing, and that`s helped lure more divers and tourist dollars to the islands. LARSEN: (Inaudible) back and forth with these, all 10 of these. LARSEN (voice-over): Luke and I jump in to see some sharks up close. LARSEN: Wow. They`re right there. TIPPLE: Uh-huh. LARSEN (voice-over): But outside of sanctuaries like this one, sharks remain at risk. (END VIDEO CLIP)