In comparison, there are around 250 commercial 'reef-line' operations, supporting three or four dories each, that harvest between 3000 and 4000 tonnes annually which is roughly equivalent to the recreational catch. Data indicates that current catch levels are sustainable, however most agree that any increased 'effort' will affect this sustainability. This does not necessarily mean that all populations of fish are 'healthy' or 'natural'. Comparisons between reefs where fishing is allowed and those where it is prohibited indicate that fishing can cause localised changes. Studies show decreases in the number and the average size of coral trout and red-throat sweetlip emperor which are specifically targeted by fishermen and heavily exploited.
Coral reefs make up only five per cent of the area of the Great Barrier Reef.
The region between the edge of the continental shelf and land, that is not coral reef, is known as inter-reef area, or the Great Barrier Reef lagoon. Our knowledge and understanding of these areas is relatively poor, and so management decision making is difficult. The inter-reef communities are an important part of the World Heritage Area with high biodiversity values. The area supports a valuable trawl fishery landing about 7000 tonnes of prawns and 1000 tonnes of scallops per year, as well as sand-crabs, lobsters and some fish. High intensity trawling can have substantial impacts on the animals living on the seabed, with up to 90 per cent of biomass being removed.