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Accounting for post-release mortality in data-limited, length-based assessments for four demersal fish species with varying life histories
No full textReleased (or discarded) fish from recreational and commercial line fisheries can experience significant levels of post-release mortality (PRM), affecting sustainability. Although PRM effects are often considered in data-rich (integrated model) assessments, this is uncommon in data-limited assessments. This study investigates impacts of PRM when applying data-limited, length-based assessment methods for four reef-dwelling demersal fish species in temperate Western Australia (Glaucosoma hebraicum, Chrysophrys auratus, Choerodon rubescens and Epinephelides armatus). These species differ considerably in their biology and susceptibility to PRM. For each species simulations were undertaken to (1) evaluate the reliability of a length-based catch curve (LBCC) method for estimating fishing mortality (F) and selectivity parameters, and (2) predict the impacts of different PRM levels on values of relative biomass, i.e. ratios of fished to unfished equilibrium spawning biomass (Brel), estimated using a length-based equilibrium analysis (LBEA). LBEA extends length-based per-recruit analysis to incorporate a stock-recruitment relationship as well as allow for PRM. On average, estimates of F and selectivity parameters from LBCC for each species were unbiased when applied to simulated data. Precision decreased, however, when LBCC was fitted to data simulated with recruitment variation. For a given F, increased PRM levels reduced Brel for all species, with the extent of impacts varying depending on species biology. LBCC was then applied to two actual datasets, firstly to lengths for all fish that had either been retained or released during historical recreational fishing trips (to estimate gear selectivity), and secondly to length data for retained fish from recent charter fishing (to estimate F and selectivity of landings). The resultant estimates were then used in LBEA to estimate Brel with and without accounting for PRM. Relative impacts of PRM varied among species depending on their biology and size limits. While PRM was predicted to have limited impact on Brel for C. rubescens (as fish are not fully selected by the gear until they attain a relatively large size), accounting for PRM resulted in estimates of Brel (at their current estimated F levels) being reduced by 31 % for G. hebraicum, 36 % for C. auratus and 23 % for E. armatus. It is recommended that, where evidence of PRM exists for a species, this be accounted for in data-limited assessments
Initiation of a farming systems trial series in Western Australia
No full textIn recent years substantial changes to Western Australian broadacre farming systems include large reductions in the area of pasture and grain legumes, increased canola production and more frequent cereal plantings (Harries 2023). In addition, the use of farm inputs such as pesticide and fertiliser have increased. To understand the implications of these changes on production constraints across the rotation, multi-year trials, that are managed as per farmer practice, are required. To achieve this, a similar approach as Eastern Australian colleagues was utilised, combining rotation x nitrogen fertiliser rate x sowing time treatments to simulate a wide range of current and alternative farming systems. In 2023 three trial sites were established: Northampton (Northern medium rainfall), Merredin (Central low rainfall) and Lake Grace (Southern medium rainfall). These trials test a range of crop and pasture rotations over four years
Agronomic practices to enhance weed management
No full textSome agronomic practices, such as crop choice and sequence and improving crop competition and pasture competition, can improve crop environment and growth, and the crop\u27s ability to compete with weeds
Factors affecting herbicide performance
No full textHerbicide performance can vary greatly depending on factors including compatibility of herbicides, water quality, sprayer decontamination, and controlling stressed weeds. This page outlines these issues and demonstrates how to assess herbicide performance to achieve the best from your herbicides
Lupin root diseases - diagnosis and management
No full textRoot, hypocotyl and stem base diseases can be significant problems in lupin crops, reducing stand density, plant vigour and yield. Root disease is present in nearly all narrow leafed lupin (Lupinus angustifolius) paddocks but in the majority of paddocks has only a small impact on crop development. However, in paddocks where high levels of root rot occurs, plant establishment, seedling vigour and crop yield can be significantly affected.
When a root disease is present in a crop very little can be done to manage it in that cropping season. It is therefore vital that the cause is correctly identified to allow appropriate management to take place before sowing the next lupin crop. Correct identification can be made from symptoms on the root and hypocotyl or stem base of affected plants. Above ground symptoms such as poor emergence, patches in crops, uneven and stunted growth, yellowing of plants and wilting or death under water stress, particularly at flowering and grain fill, can indicate the presence of root disorders. These above ground symptoms are rarely diagnostic as many biotic and abiotic disorders will have similar above ground expression.
This page describes above and below ground symptoms of the common root and hypocotyl diseases occurring in lupins in Western Australia (WA). Management recommendations for each are outlined
Net form net blotch and its management in barley
No full textNet form net blotch is a fungal disease that can reduce yield and grain quality of barley crops. It can vary in appearance depending on the pathogen, variety of barley, and stage of infection. This factsheet describes the symptoms, and how this disease is managed
Stem rust and its management in wheat
No full textStem rust (Puccinia graminis f. sp. tritici) is a foliar disease that can significantly reduce wheat yields if it occurs in early spring and is not controlled. Risk factors, management strategies (including variety choices and foliar fungicides), and yield loss from different varieties are discussed here.
In Western Australia, stem rust typically causes losses of 10 to 50% in wheat, but this can increase to 90% when it occurs in early spring and is not controlled.
Stem rust affects wheat and triticale, but barley can also be a host during summer months.Stem rust produces large, reddish-brown spore masses on both sides of the leaf, on leaf sheaths, stems, and outside of heads. The pustules have tattered edges.
Stem rust requires living plants on which to grow and reproduce. To infect crops during the season, it must survive summer by infecting volunteer cereals or grass hosts, known as the ‘green bridge’.
Other rusts that infect wheat in WA are stripe rust and leaf rust, but these do not occur on stems. For more information on these rusts, see the page, Managing stripe rust and leaf rust in wheat in Western Australia
Stop crop weed seed set
No full textNumerous options can be used to prevent weed seed set, which provides an opportunity to control weeds in the pasture, late fallow, late stubble, and in-crop phases for the next season
Wheat response to foliar-applied phosphorus is determined by soil phosphorus buffering
No full textIn no-till cropping systems, banding of phosphorus (P) fertiliser at seeding results in low use efficiency due to chemical reactions in soil. Foliar P has the potential to allow grain producers to respond tactically with P application after sowing when P supply from soil and fertiliser is not meeting crop demand. The objective of this study was to evaluate the effectiveness of foliar P on wheat grain yield, grain quality, biomass yield, P uptake and P use efficiency indices. Nine field experiments were conducted to investigate the response of wheat to foliar P. Three rates of P, 0, 2.5 and 5.0 kg/ha, as phosphoric acid (H3PO4 85%) were applied to wheat at three different growth stages: first tiller emergence (Z21), first node detection (Z31) and flag leaf emergence (Z39). Grain yield responses ranging from 176 kg/ha to 505 kg/ha to foliar-applied P were observed in six out of nine experiments. The percent grain yield response to foliar P was negatively related to the P buffering index (PBI, 0–10 cm soil depth), which is attributed to greater sorption by soil of the foliar P at the higher PBI levels. Mean agronomic efficiency (AE) across the experiments was 111 kg/kg P but reached up to 232 kg/kg P. It was also evident that foliar P has the potential to improve P concentration in shoots and grains and increase P uptake but with no or minimal effect on grain quality. Our results suggest that a combination of tissue testing at the seedling stage and soil P buffering can be used to guide when foliar P application is likely to increase grain yield in wheat
BEN Signage Installation Map – Shire of Denmark
No full textBEN Signage Installation Map – Shire of Denmarkhttps://library.dpird.wa.gov.au/gis_bens/1026/thumbnail.jp