Commercial trawl fisheries

Square mesh codend bycatch reduction device

The square mesh codend is a type of bycatch reduction device (BRD). Industry-based research shows that the square mesh codend BRD is highly effective in scallop and prawn fisheries.

In the Queensland east coast trawl fishery, BRDs are mandatory for all otter trawl nets and all beam trawl nets. For the full specifications of BRDs, check the fisheries legislation.

Research shows that bycatch was reduced by 77% when turtle excluder devices (TEDs) were also used in combination with square mesh codend BRDs. Trials in scallop fisheries showed there was no loss of marketable scallops and there were 63% fewer undersized scallops caught.

The square mesh codend also performed well in scientific trials on reducing the impact of trawl fisheries on protected sea snakes. The research found square mesh codend BRDs to be highly effective, reducing sea snake catch by 60% (Courtney et al. 2010).

Square mesh codend BRD specifications

Minimum length of codend (A in diagram)

All prawn otter trawl nets: 50 bars (and 80 bars around)
All scallop otter trawl nets: 33 bars (and 50 bars around)
All beam trawl nets: 50 bars (and 100 bars around)

Maximum length of normal mesh (B in diagram)

All prawn otter trawl nets: 25 meshes
All scallop otter trawl nets: 15 meshes
All beam trawl nets: 25 meshes

Minimum size of square mesh (C in diagram)

Northern/central area otter trawl prawn nets: 50mm
Shallow area otter trawl prawn nets: 38mm
Deepwater net area otter trawl prawn nets: 45mm
All scallop otter trawl nets: 88mm
All beam trawl nets: 31mm

Additional specifications

Nothing is allowed to cover any of the square meshes during trawling.
The shallow area square mesh codend must have a square mesh panel installed that:
- has a mesh size of at least 45mm
- is at least 300mm wide and 300mm long.

Image of a square mesh codend bycatch reduction device.