The correct answer is: Purse seine nets.
Purse seine nets are a type of fishing net that is used to catch fish in schools. The net is made of a long, narrow piece of netting that is held open at the top by floats and at the bottom by weights. When the net is deployed, it is encircled around a school of fish and then closed at the bottom by pulling a drawstring. This traps the fish inside the net, which can then be hauled to the surface and emptied.
Purse seine nets are a very effective way to catch fish, and they are used by commercial fishermen all over the world. However, they can also be harmful to the environment, as they can catch non-target species of fish and other marine life.
Trawling is a type of fishing that uses a large net that is dragged along the bottom of the seabed. This type of fishing is very destructive to the seabed, as it can damage coral reefs and other sensitive habitats.
Long-lining is a type of fishing that uses a long line with many baited hooks attached. This type of fishing is also very destructive, as it can catch non-target species of fish and other marine life.
Aquaculture systems (ponds) are a type of fish farming that involves raising fish in ponds. This type of fish farming is relatively sustainable, as it does not damage the environment. However, it can be harmful to the fish, as they are often kept in crowded conditions and fed with artificial feed.
In conclusion, the correct answer is purse seine nets. This type of fishing is very effective, but it can also be harmful to the environment.