The reading passage lists three factors which have caused the decline of European eels and the lecturer gives his own solutions to solve the problem.
First, the reading points out that some dams are being built in most area of European waters, which will block eels’ immigration route to reproduce. However, the professor suggests that those dams could be designed with a series of hollowed tubes on them, thereby letting those baby eels get through and reach their feeding ground.
Second, even though the reading passage suggests that is it the parasites that cause the decline of eels, the professor proves that this claim is indefensible. He states that some ecologists have already found that the fattest eels which consume large amount of fish are most vulnerable to parasites. Thus, the spread of infection can be well controlled if we move these eels into areas where there are not so much fish for them to eat.
The passage also presents the third problem that eels always lay eggs secretly, so it is hard to prevent them from danger due to the difficulty of locating their breeding areas. However, the professor mentioned that the scientists can locate eels’ breeding grounds by installing some advanced electronic devices on them, thus they could spare no efforts to protect those eels. (217 words)