Minimising catches of non-target animals (bycatch) in fisheries reduces the impact on a marine community and may help to sustain the fishery in the long term. Various authors such as Brewer et al. (1996) and Kenneally (1997) have discussed ways in which the bycatch problem could be addressed. Various devices to reduce bycatch have been developed. These include exclusion devices designed to exclude larger animals (e.g., dugongs), avoidance mechanisms (e.g., raising a trawl slightly off the bottom), and filtering using a targeted mesh size. The last two approaches are particularly pertinent to invertebrates. Roosenburg and Green (2000) discuss the use of a bycatch reduction device on crab pots.


There have been relatively few studies on the invertebrate component of bycatch (see Section 6.10.1). Assessment of the bycatch (as well as target species) would be a convenient way of determining ecosystem changes over time and could be used as a management tool.


No matter what avoidance techniques are used, bycatch of non-targeted invertebrates will still be an issue. Typically, once caught the mortality of the animals in the bycatch is very high to total, even when returned to the sea quickly.

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Department of Environment and Heritage