Tiger Flathead Neoplatycephalus richardsoni

There can be a substantial level of bycatch in the fish trawl sector. In 2006, mandatory requirements for otter trawls to use 90 mm square-mesh codend panels were introduced to reduce the catch of small species and juvenile fish⁷.

Interactions also occur with animals protected under the Environment Protection and Biodiversity Conservation Act 1999, including marine mammals (dolphins, seals and sea lions), seabirds, some shark species and seahorses and pipefish (syngnathids). These interactions are reported quarterly by the Australian Fisheries Management Authority⁸ and on-board observer programs are used to validate the reporting in commercial logbooks.

In 2007, the South East Trawl Fishing Industry Association released an industry code of practice that aims to minimise interactions with fur seals, as well as addressing the environmental impacts of the fishery more generally⁹. Operators have developed other mitigation protocols that have further reduced seal mortalities, including using breakaway ties that keep the net closed until it is below depths that seals regularly inhabit, adopting techniques to close the trawl opening during recovery to minimise opportunities for seals to enter the net, switching off gantry lights that are not required during night trawling to avoid attracting bait species and seals, and dumping offal only when the boat is not engaged in deploying or hauling gear⁹.

In 2011, AFMA mandated individual vessel seabird management plans¹⁰. The seabird action plans are used in the Commonwealth Trawl Sector to mitigate the impacts of trawling on seabirds. Seabird mitigation measures include warp deflectors (‘pinkys’), bird bafflers (a system of ropes and PVC piping that protects the warp cable) and seal excluder devices.

The effects of trawl fishing on the marine environment are assessed through an environmental risk assessment and risk management framework and mitigated through spatial closures, and the implementation of bycatch and discard workplans in the Commonwealth Trawl Sector and Great Australian Bight Trawl Sector fisheries.

Danish-seine and otter trawl interact with a broad range of habitat types. However, an ecological risk assessment indicates that fishing operations on sandy substrates of the inner to mid shelf, where Tiger Flathead are targeted, do not present a high risk to habitats^11,12.

Danish-seining has the potential to affect seahorses and pipefish (syngnathids) because Danish-seiners operate in relatively shallow waters and use nets with a small mesh size. An ecological risk assessment (ERA) indicated that the Spiny Pipehorse was at low risk because the fishery overlaps with only a small portion of the range of this species¹³.

Discarding of quota species can be significant in some parts of the Commonwealth Trawl Sector. However, discard rates for Tiger Flathead are low, generally around 5 per cent¹.