3.Researching some poison to kill the snake head. Though poison will also kill native fishes in the river; people can restock native fishes.

Listening:

The listening contradicts all methods proposed by the author of the passage and points out their potential problems.

1.Even if people do not transport the snake head. the spread will still continue. The reason is that there are already many snake heads, and these snake heads will move to other rivers even without human’s efforts. because they can live and move on land as long as they are moist

2.Educating fishers to catch snake head will not help stop the spread of snake head. Conversely. it may lead to the increase of snake head. Because when fishers realize they can make profit by catching snake head. they wil1 introduce snake head to other water bodies and raise snake head in order to catch more snake head, even this is illegal.

3.It is true that native fishes can be restocked; however; poison will also kill some insects and micro organisms, which cannot be restocked. So, native fishes that feed on these insects and micro organisms cannot grow to their original size. This is irreversible.