Bottom trawling is trawling

Trawling

Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net that is used for trawling is called a trawl....

 (towing a trawl, which is a fishing net

Fishing net

A fishing net or fishnet is a net that is used for fishing. Fishing nets are meshes usually formed by knotting a relatively thin thread. Modern nets are usually made of artificial polyamides like nylon, although nets of organic polyamides such as wool or silk thread were common until recently and...

) along the sea floor. It is also often referred to as "dragging".

The scientific community divides bottom trawling into benthic

Benthic zone

The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such...

 trawling and demersal

Demersal zone

The demersal zone is the part of the sea or ocean comprising the water column that is near to the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of the larger profundal zone....

 trawling. Benthic trawling is towing a net at the very bottom of the ocean and demersal trawling is towing a net just above the benthic zone.

Bottom trawling can be contrasted with midwater trawling (also known as pelagic

Pelagic zone

Any water in a sea or lake that is not close to the bottom or near to the shore can be said to be in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means "open sea". The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes...

 trawling), where a net is towed higher in the water column.