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State of the fisheries: Status reports of the fisheries and aquatic resources of Western Australia 2023/24
No full textThis edition of the “State of the fisheries” continues the tradition of annually reporting on the status of exploited fish and their habitats in Western Australia. Critically, the reports provide overviews of the science outcomes that underpin management of fishing across the state.
Scientifically assessing the status of fish resources and potential impacts on ecosystems is inherently challenging; I acknowledge and thank the dedicated fisheries science teams and various support staff for again producing outstanding, robust scientific results that are summarised herein. I similarly acknowledge (i) the fisheries management team who use the science outcomes in policy development and to adjust regulatory settings; and (ii) the compliance team for ensuring regulations are enforced.
While fisheries science is a highly-applied branch of science directed towards policy and regulation, maintaining close links to the academic world is paramount for ensuring our science is contemporary with global standards, and hence, the best it can be. In this regard, the DPIRD fisheries science team strives to maintain collaborative networks with other national and international experts around the world.
Additionally, they pursue publication of scientific work in independent, peer-reviewed science journals.
Meeting new challenges, such as climate change, better engaging with Aboriginal peoples, community projects (e.g., Fish Aggregating Devices) and contributing to marine spatial planning requires ongoing consideration of the balance between focussing just on the current business-as-usual assessments versus exploring innovative ways of working in the future. For example, better positioning ourselves to embrace new technologies and machine learning (“AI”) just doesn’t happen by itself. These new challenges/opportunities require considerable focussed effort.
Strategically, working towards future directions must occur at the same time as the core science tasks that deliver world-class science outcomes for management. In turn, this dictates that fisheries science in Western Australia needs to continually evolve to meet contemporary community expectations, that world-class management is based on world-class assessment of our state’s aquatic resources.
Dr Dan GaughanChief Fisheries Scientisthttps://library.dpird.wa.gov.au/an_sofar/1016/thumbnail.jp
Agricultural groundcover update December 2023
No full textSummary About 96% of the grainbelt had adequate vegetative groundcover (more than 50%) to prevent wind erosion in December 2023. In the northern half of the grainbelt, a larger-than-average area has 51–60% groundcover, which is expected to decrease to below 50% over the summer. Just under 4% of the grainbelt (553,000 ha) had less than 50% groundcover, which is inadequate to prevent wind erosion. West Midlands Ag Soil Zone had the highest risk of wind erosion and 11.4% of this farmland had inadequate groundcover. Less than 0.5% of the grainbelt had a high to very high risk of wind erosion because groundcover levels were less than 30%
Fisheries Occasional Publication No.146 - Yabbie Aquaculture in Western Australia, March 2024
No full textPolicy relating to the assessment of yabbie aquaculture proposals and principles for assessmenthttps://library.dpird.wa.gov.au/fr_fop/1061/thumbnail.jp
Agricultural groundcover update February 2024
No full textAbout 92% of the grainbelt had adequate (more than 50%) vegetative groundcover to prevent wind erosion in February 2024. Nearly 8% of the grainbelt (1,193,400 ha) had less than 50% groundcover, which is inadequate to prevent wind erosion. The northern grainbelt had the highest risk of wind erosion and 16.5% of this farmland had inadequate groundcover. Less than 0.7% of the grainbelt had a high to very high risk of wind erosion because groundcover was less than 30%
Emissions and profitability: how do nitrogen and lime affect both?
No full textIn-season adjustment of nitrogen can improve profitability and reduce emissions. Nitrogen applications for economic rather than yield maximisation can reduce emissions. Neglecting lime applications to reduce emissions likely reduces profit
Spot form net blotch and its management in barley
No full textSpot form net blotch (SFNB) has become increasingly more common in Western Australia (WA) due to the widespread cultivation of susceptible varieties, such as Spartacus CL and RGT Planet.
These crops generate large amounts of inoculum, which is carried between seasons on infected stubble. Crops grown onto or located close to infected stubble are at greatest risk of infection. The disease can be effectively managed using a combination of varietal selection, crop rotation, and fungicides
Reduce crop weed seed numbers in the soil
No full textThere are various methods of weed control in the pre-sowing phase, including removing weed seed numbers in the soil, fallow, stubble, and by various methods. This factsheet covers some of the methods, including:
• Burning crop residues to reduce the surface seed bank of many weeds
• Encouraging insect predation of seed
• Inversion ploughing to bury weed seeds at a depth they can’t germinate
• Autumn tickle to encourage earlier germination of weed seeds for destruction using a knockdown herbicide
• Delaying sowing to allow greater germination of weed seeds for destruction using a knockdown herbicide or cultivation, prior to crop sowing
Fertiliser strategies to boost crop yield in re-engineered soil profiles
No full textSubsoil constraints such as compaction and acidity are prevalent in WA and hinder the development of deep root systems. Duplex soils, common in the region, exacerbate these challenges and lead to suboptimal yields. A field-based soil re-engineering experiment involving soil loosening and incorporation of ameliorants to a depth of 80 cm in a duplex soil profile with subsoil acidity and compaction, demonstrated that barley yields could be doubled by deep incorporation of lime, fertiliser, and clay compared to surface application of the same ameliorants. However, incorporating fertiliser to an 80 cm depth presents practical challenges to the annual replenishment of crop nutrients. To address this, two controlled environment experiments were conducted to develop fertiliser strategies for re-engineered soils based instead on surface banding and topdressing.
Results suggest that after increasing soil pH above the minimum target of 4.8 by incorporating lime and addressing soil compaction by loosening the soil, to 80 cm depth, barley yields of re-engineered soils can be maintained by surface application of inorganic fertiliser at increased rates. We found that 150 kg/ha of surface-applied N was enough to optimise barley grain yield, but higher barley protein could be achieved by applying more N. These findings help optimise fertiliser management practices of re-engineered soils, thereby contributing to the sustainability of broadacre cropping
Pilbara Demersal Scalefish Resource Recovery Plan 2023- 2043 (Phase 1)
No full textThe Pilbara Demersal Scalefish Resource (PDSR) includes over 60 demersal scalefish species. The resource is accessed by the Pilbara Trap Managed Fishery, Pilbara Fish Trawl (Interim) Managed Fishery, and the Pilbara Line Fishery (PTMF, PFTIMF & PLF respectively) as well as the recreational and charter fisheries.
The PDSR is managed in accordance with the North Coast Demersal Scalefish Resource Harvest Strategy (Harvest Strategy). The sustainability objectives of the PDSR are set out in the Harvest Strategy and monitored via the use of an indicator species approach, whereby the status of key species is considered representative of the status of the resource. Under this approach the spawning biomass level of red emperor (Lutjanus sebae), bluespotted emperor (Lethrinus punctulatus) and rankin cod (Epinephelus rankini) are monitored against target, threshold, and limit reference levels.
Assessments of the status of other key non-indicator species, such as goldband snapper (Pristipomoides multidens), are also undertaken periodically. In November 2023, the Department of Primary Industries and Regional Development (DPIRD) finalised the Assessment of the Status of the Pilbara Demersal Scalefish Resource (Fisheries Research Report (FRR) No. 338).
The 2023 PDSR stock assessment indicated that the relative female spawning biomass of: red emperor (indicator species) had breached the limit reference level and is classified a depleted stock; bluespotted emperor (indicator species) was above the threshold reference level and is classified a sustainable stock; goldband snapper (retained non-indicator species) was between the limit and the threshold reference level and is classified a depleting stock; and rankin cod (indicator species) was not assessed but will be included in the next periodic stock assessment for the PDSR scheduled for completion in 2026.
In accordance with the Harvest Strategy, where the status of an indicator species (or non-indicator species) breaches the threshold or limit reference level, a review is undertaken, and a management response is implemented to recover the resource within two generations (or a maximum of 20 years). A resource is considered to have recovered when the spawning biomass level of all indicator species is above the threshold reference level and being managed to the target reference level.
Model projections outlined the 2023 stock assessment estimated that the catch of red emperor needs to be reduced by at least 38% (from 2022 levels) to recover the stock to above the threshold reference level within 20 years. Given the outcomes of the 2023 stock assessment, the indicator species approach has been applied such that red emperor (high sustainability risk) is considered an indicator for the suite of species with similar biological characteristics (e.g. late maturation relative to selection by fishing gear, relatively long lived). These species include goldband snapper (also high sustainability risk), saddletail snapper (Lutjanus malabaricus), crimson snapper (Lutjanus erythropterus), and other species that share similar life history characteristics.
Similarly, bluespotted emperor (medium/acceptable sustainability risk) is considered an indicator for the suite of species with similar biological characteristics (e.g., early maturation relative to selection by fishing gear, shorter lived), including brown-striped snapper (Lutjanus vitta)