The correct answer is: All of the above.
Trawling, purse seine nets, long-lining, and aquaculture systems (ponds) are all modern fishing techniques that may be used in Manipur.
Trawling is a method of fishing that involves dragging a net along the seabed. This method is often used to catch bottom-dwelling fish, such as cod and haddock.
Purse seine nets are large, circular nets that are used to encircle schools of fish. The net is then closed at the bottom, trapping the fish inside.
Long-lining is a method of fishing that involves setting a long line of baited hooks. The line is often set at night, and the fish are caught when they bite the hooks.
Aquaculture systems (ponds) are man-made enclosures where fish are raised. This method is often used to raise freshwater fish, such as carp and tilapia.
All of these methods are effective at catching fish, and they can be used to catch a variety of different species. The best method to use will depend on the type of fish that you are trying to catch, the location of the fishing grounds, and the available resources.