From MarineBiotech Infopages
Definition of Dredging:
(1) The action of removing material from the seabed.
(2) Bottom sampling equipment towed along the seabed for collecting benthic sediment and organisms. Dredges are also used for the commercial collection of benthic organisms, e.g. scallops, or of sediment and may be a suction or hydraulic device.
This is the common definition for Dredging, other definitions can be discussed in the article