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Useful Definitions


Aquaculture: The rearing or cultivation of aquatic animals or plants for food, e.g. mussels, oysters, salmon. Also called 'fish farming'.

Bycatch: Aquatic life that is killed or damaged during the fishing process but is not retained as catch and sold, e.g. soft corals, sea turtles, albatrosses, deep sea sharks, unwanted fish.

Byproduct: Any non-target fish or shellfish species that is caught and retained in a fishery before being sold to the market.

Capture fisheries: Wild aquatic species that are caught for sale using a range of fishing methods.

Depleted: Overfishing has reduced a stock to a very low level of abundance, requiring rebuilding of stock, e.g. Southern bluefin tuna, school shark.

Discarding: the practice of returning unwanted catches to the sea,
either dead or alive, either because they are too small, the fisherman has no quota, or because of certain catch composition rules.

Ecosystem: An interacting and inter-dependent community of living organisms and physical structures that functions as a unit in nature.

Environmentally limited: Has reduced productivity due to external impacts associated with habitat modifications or environmental factors. Reduced stock levels are not primarily due to fishing, although fishing may be a contributing factor to concerns regarding low stock levels.

Extinction: Commercial extinction - a species is depleted to the extent that it is no longer commercially viable to fish. Ecological extinction - a species has declined to such low abundance that it ceases to play its role in the ecosystem. Biological extinction - a species is permanently lost, with no living members still in existence.

Fully fished: A fish stock is 'fully fished' when fishing pressure is at the maximum limit of what can be sustained before overfishing will likely occur.

Ghost fishing: The accidental capture and killing of marine wildlife in fishing gear, usually nets or traps, that have been lost at sea.

Imported: Species imported from wild fisheries and aquaculture enterprises operating outside Australia, e.g. hoki from New Zealand, Vannamei prawns from Southeast Asia.

Introduced: Species introduced into Australia's marine environment deliberately for aquaculture production or stocking programs, e.g. Trout, Atlantic Salmon.

Keystone species: A species that has a major influence on the structure or functioning of an ecosystem. Its presence affects many other members of the ecosystem and, if its population dwindles or disappears, there can be far reaching consequences for the ecosystem, e.g. sharks.

Observers: Observers are individuals on board fishing boats who are independent of the government and the fishing industry. Their job is to record information about the fishery operation, including interactions with threatened, endangered or vulnerable wildlife. Their reports provide credible records of fisheries impacts on marine wildlife. Observer programs are an essential component of good fisheries management.

Overfished: A stock is overfished when it has been depleted below a defined acceptable level.

Recruitment overfished: Overfishing has reduced the population to a level where recruitment (the number of larval fish added to the stock) is significantly suppressed. The result may be stock collapse if overfishing is prolonged and combined with poor environmental conditions.

Growth overfished: Too many small fish are caught. Reducing catches and/or increasing the size at which fish are caught would help rebuild the fishery. An overfished stock can have negative knock-on impacts on the ecosystem as a whole.

Overfishing: The extent of fishing is too high and fish are being removed at a rate which is unsustainable. Continued overfishing will lead to an overfished stock (see above).

Seafood: Any fish or shellfish species caught or farmed for human consumption.

Sustainable fisheries: Fisheries are ecologically sustainable when the stocks of target species, non-target species and their surrounding ecosystems are maintained over the long-term. A truly sustainable fishery meets the long-term needs of fishermen, seafood consumers and the environment together.

Target species: The fish or shellfish species that are the primary or intended catch of a particular fishery. Often the most highly sought and most valuable species are selected or targeted for fishing.

Wild fisheries: See 'capture fisheries'.