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WA, Commonwealth waters
- Tiger prawns live in tropical waters, and are short-lived and fast-growing. Long-term fishing records and estimates of the number of breeding animals indicate that stocks are healthy.
- There is concern over catch declines in WA's Exmouth Gulf region. Area closures are now in place to protect stocks.
- Tiger prawns are caught using otter trawls that operate just above the seafloor. Trawling is conducted over sandy and muddy seafloors in the Commonwealth and WA fisheries, and has a relatively low impact on the marine environment.
- Bycatch reduction measures are mandatory in these fisheries, and have reduced accidental turtle catches.
- All fisheries interact with threatened species, including critically endangered species of sawfish, sea snakes and pipefish. Although efforts have been made to reduce the impact of fishing on these species, catches remain significant but are not thought to be driving further declines in populations.
- Commonwealth Northern Prawn Fishery & Torres Strait Prawn Fishery (3,700t in 2015-16)
- WA Shark Bay Prawn Managed Fishery, Exmouth Gulf Prawn Managed Fishery (1,307t in 2015)
The name ‘tiger prawn’ refers to two species – grooved and brown tiger prawns. These two species live in tropical waters and are short-lived and fast-growing.
In the Commonwealth fisheries, although there is some uncertainty around the stock structure of tiger prawns, there are no indications of significant risks to either species as a result of fishing. In WA, stock health is monitored by assessment of the biomass of tiger prawns as well as the number of young prawns coming in to the fishery. All indications are that tiger prawn stocks are healthy in WA.
Prawns are caught using otter trawls that operate mainly over mud and sand. Otter trawls operate just above the seafloor when targeting tiger prawns, which has the potential to cause significant habitat disturbance. Habitat types are relatively well understood in all fishing areas, tend not to support sensitive marine communities and are fairly resilient to disturbance. Relatively little of the areas in which the Commonwealth fisheries operate is protected in spatial closures or marine parks. In WA, 62% of Shark Bay is protected from the impacts of trawling in marine parks, with marine parks providing some protection in Exmouth Gulf.
Bycatch reduction devices (BRD) and Turtle Exclusion Devices (TEDs) reduce the amount of threatened and other species that are caught and killed in fishing gear. BRDs and TEDs are mandatory in all these fisheries and have been successful in reducing turtle deaths. However, threatened species bycatch remains an ongoing issue.
The main Commonwealth fishery has been proactive in attempting to reduce its impacts on threatened species. Although catch of sea snakes remains high, there are no indications that fishing activity is resulting in population declines of any of the species caught. Endangered sawfish, including the IUCN listed ‘Critically Endangered’ green and ‘Endangered’ dwarf sawfish are caught every year, although it is complex to design modified fishing gear to reduce sawfish mortalities because the shape of their rostrums means they are especially prone to entanglement. Due to the wide distribution of sawfish, including in non-fished areas, experts have assessed that prawn fishing alone is not driving further declines in these species.
The WA-managed fisheries also report interactions with sawfish, turtles and sea snakes although fishery reports suggest that significant impacts on threatened species is unlikely. Fishery plans include the introduction of an independent observer program, although it is unclear whether this has been implemented or progressed.
The Commonwealth fisheries have robust and transparent management arrangements in place, including observer programs, requirements to reports discards, assessments of the risk of the fishery to threatened species, plans in place to reduce bycatch that have proved to successfully deliver that objective and management actions to rectify issues in the fishery when they occur. It is likely these management arrangements will maintain the progress of these fisheries to reduce the impact on endangered wildlife in the future.
Marine parks and spatial closures provide some protection for endangered wildlife and marine habitats. Both are in place in areas where the WA fisheries operate. Commonwealth marine parks are set to be established in 2018, though it is notable that sectors of industry sought, and may secure, significant reductions in the area of the fishery protected from trawling.