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Fishing pressure

There are two fishing pressure indicators used for State of the Environment reporting (Estuaries and the Sea) [1]:

• the area swept by demersal trawlers, and the distribution and frequency of trawling over different locations in each trawling ground (e.g. Indicator 4.5); and
• the extent of fishing by gill net, longline, drop line and meshing operations according to fishery and sub-region, and on a day-km basis (e.g. Indicator 4.6).

In addition, the number of fisheries management plans that contain indicators for monitoring impacts on non-target organisms, and the number of indicators, is an 'integrated management' indicator (Indicator 7.8) used also in State of the Environment reporting for Estuaries and the Sea [1].

Photo 1. Popular recreation species (including snapper) in coastal waters of Perth. Photo by Tom Rose (Waters and Rivers Commission, Western Australia).

Coastal issues arising from fishing pressure

The economic consequences of declining stocks of commercially harvested fish is the most obvious issue that relates to fishing pressure. However, fishing can have many other impacts on coastal ecosystems i.e.:

• the removal of non-target species (benthic invertebrates and fish) as by-catch [1];
• the removal of large numbers of top-predators (e.g. by long-lines, meshing and gill nets) and increased ratio's of plantivore:demersal fish biomass [2];
• physical damage to, and removal of critical habitats [1] such as seagrass meadows and oyster reefs due to destructive fishing practices (these habitats can sometime act as refuges, and their removal can exacerbate the effects of low dissolved oxygen concentrations and anoxic & hypoxic events on organisms);
• changes in the abundance, diversity and community structure of benthic invertebrates; and
• kills of seabirds, marine mammals and sea turtles, due to entanglement in nets and longlines [1].

All of these impacts can have indirect effects on ecologically-dependent species.

Existing information and data

More information on fishing pressure and integrated management indicators (e.g. reporting scales, outputs, analysis and interpretation and data sources) can be found in the Estuaries and the Sea volume of Environmental Indicators for National State of the Environment Reporting [1].

References

1. Ward, T., Butler, E. and Hill, B. 1998. Environmental Indicators for National State of the Environment Reporting, Estuaries and the Sea, Commonwealth of Australia, pp. 81. www.ea.gov.au/soe/coasts/estuaries-ind.html.
2. Caddy, J.F. 2000. Marine catchment basins effects versus impacts of fisheries on semi-enclosed seas. International Council for the Exploration of the Sea - Journal of Marine Science 57, 628-640.
3. Breitburg, D. 2002. Effects of hypoxia, and the balance between hypoxia and enrichment, on coastal fishes and fisheries. Estuaries 25(4b), 767-781.