This project is needed to reduce the environmental footprint and increase the efficiency of Australian mud crab fisheries. Pots are the main gear type used in most cases, but the type of pot used differs between jurisdictions and/or sectors. Commercial crabbers in the NT and much of the NSW fishery use rigid, galvanised wire mesh pots that are moderately selective. Despite this, large numbers of crabs must still be measured and released, introducing a source of handling and post-release mortality of unknown magnitude.

Another source of cryptic mortality is cannibalism of others in the pot (particularly soft and/or undersized crabs) but again, the extent of this problem is hard to ascertain. Ghost fishing by wire mesh pots is also a concern. However, the destructive effects of corrosion in conjunction with an access door that swings open once the retaining strap perishes, limits the ghost potting potential of this gear type.

Queensland and WA commercial crabbers and many NT and QLD recreational fishers use collapsible nylon mesh pots of various types. The mesh size of nylon pots is often smaller than that of wire mesh pots, meaning they are less selective. A secure pot closure mechanism in conjunction with a poorly biodegradable body also means there is little scope for organisms to escape from nylon pots, particularly if the gear is lost. This combination of factors suggests that cryptic mortality and ghost fishing may also be a problem where nylon pots are used.

One means to alleviate the problems mentioned above is to facilitate the exit of undersized crabs (and other bycatch) from pots by using more selective meshes or fitting escape vents (as used in crab and lobster fisheries elsewhere). This proposal seeks funds to quantify and improve the selectivity of gear used by Australian mud crab fisheries.