The environmental management of prawn farming in Queensland - worlds best practice

This article provides a summary of research undertaken during a seven-year study from 1995-2002 which focussed on prawn farm ecosystems, their ecological impacts, and cost-effective effluent treatment systems.

Predicting the cost of eradication for 41 Class 1 declared weeds in Queensland

The feasibility of state-wide eradication of 41 invasive plant taxa currently listed as ‘Class 1 declared pests’ under the Queensland Land Protection (Pest and Stock Route Management) Act 2002 was assessed using the predictive model ‘WeedSearch’. Results indicated that all but one species (Alternanthera philoxeroides) could be eradicated, provided sufficient funding and labour were available. Slightly less than one quarter (24.4%) (n = 10) of Class 1 weed taxa could be eradicated for less than $100 000 per taxon. An additional 43.9% (n = 18) could be eradicated for between $100 000 and $1M per taxon. Hence, 68.3% of Class 1 weed taxa (n = 28) could be eradicated for less than $1M per taxon. Eradication of 29.3% (n = 12) is predicted to cost more than $1M per taxon. Comparison of these WeedSearch outputs with either empirical analysis or results from a previous application of the model suggests that these costs may, in fact, be underestimates. Considering the likelihood that each weed will cost the state many millions of dollars in long-term losses (e.g. losses to primary production, environmental impacts and control costs), eradication seems a wise investment. Even where predicted costs are over $1M, eradication can still offer highly favourable benefit:cost ratios. The total (cumulative) cost of eradication of all 41 weed taxa is substantial; for all taxa, the estimated cost of eradication in the first year alone is $8 618 000. This study provides important information for policy makers, who must decide where to invest public funding.

Assessing the biological control potential of an adventitiously-established "pest", Scirtothrips aurantii (Faure), on a weed, Bryophyllum delagoense (Eckl. & Zeyh.), in Queensland

South African citrus thrips (Scirtothrips aurantii) established adventitiously in Australia. Although it is a major horticultural pest in Africa, it is now advocated as a possible biological control agent against Bryophyllum delagoense Eckl. & Zeyh. (Crassulaceae). To evaluate the biocontrol potential of S. aurantii a two year field study was conducted on the western Darling Downs of southern Queensland. Imidacloprid insecticide was applied to two quadrats at each of 18 field sites to assess, in the absence of S. aurantii, the persistence of individual plants and to quantify propagule production and recruitment by this declared weed. A third quadrat was left, as a control, to be infested naturally by S. aurantii. When released from herbivory by thrips in the field, plants grew significantly more, flowered more, and were significantly more fecund than plants in the quadrats with S. aurantii. Increases in growth and fecundity translated into significantly increased plant numbers but not increased recruitment. Recruitment even declined in experimental quadrats, through the indirect effects of releasing plants from herbivory. Field sampling also revealed that S. aurantii may be sensitive to seasonal climatic fluctuations. These and other local climatic influences may limit the biological control potential of the insect.

Rocky Reef Fisheries in Queensland

Addressing knowledge gaps for the sustainable management of rocky reef fisheries.

Spanner Crabs Threatened in Queensland

The fishing industry of Queensland, embracing both marine and fresh waters, has weathered some rough seas over the past decade. Now rich resources of fish and crustacean species, many of which have as yet an unquantified potential, are being over exploited by fishermen who choose to ignore regulations in order to make quick dollars.

Climate Q - Develop capacity to adapt to climate change in Queensland

Aims to build adaptive capacity within Qld's mixed farming (cropping/beef) sector.

Evaluating the efficacy of the EZ-Ject herbicide system in Queensland, Australia

The EZ-Ject herbicide system was evaluated as a stem injection method for controlling woody weeds in a range of situations where traditional chemical application methods have limited scope. The equipment was trialled on three Queensland weed species; pond apple (Annona glabra), velvety tree pear (Opuntia tomentosa) and yellow oleander (Cascabela thevetia); at five different cartridge densities (0, 1, 2, 3 and 4) and with two herbicides (glyphosate and imazapyr). Cartridges filled with imazapyr were significantly more effective at controlling the three woody weed species than those filled with glyphosate. Injecting plants with three imazapyr cartridges resulted in plant kills ranging from 93 to 100%, compared with glyphosate kills of 17 to 100%. Pond apple was the most susceptible species, requiring one imazapyr cartridge or two glyphosate cartridges to kill 97 and 92% of the treated plants. Plant mortality increased as the number of cartridges injected increased. Mortality did not differ significantly for treatments receiving three and four imazapyr cartridges, as these cartridge densities met the criterion of injecting one cartridge per 10-cm basal circumference, a criterion recommended by the manufacturers for treating large plants (>6.35 cm in diameter at breast height). The cost of treating a weed infestation of 1500 plants ha–1 with three cartridges per tree is $1070 ha–1, with labour costs accounting for 16% of the total. The high chemical costs would preclude this technique from broad-scale use, but the method could have application for treating woody weeds in sensitive, high conservation areas.

Two varieties of the invasive liana, cat’s claw creeper, Macfadyena unguis-cati (Bignoniaceae) in Queensland, Australia

The invasive liana cat’s claw creeper, Macfadyena unguis-cati, native to tropical Central and South America, is a major environmental weed in Queensland and New South Wales (NSW). Two morphologically distinct cat’s claw creeper varieties occur in Australia, a ‘short-pod’ variety that is widespread through Queensland and NSW and a ‘long-pod’ variety restricted to a few sites in southeast Queensland. In this study we report the differences in the above-ground morphological, phenological and reproductive traits between the two varieties. The ‘long-pod’ variety has significantly larger leaves, larger pods, and larger number of seeds per pod than the ‘short-pod’ variety. The ‘short-pod’ variety has a slightly wider pods, and thicker leaves than the ‘long-pod’ variety. Both varieties have a yellow trumpet shaped flower, but the flower of the ‘long-pod’ variety has a deeper hue of yellow than the ‘short-pod’ flower. The fruits of the ‘short-pod’ variety mature in late summer to early autumn while the fruits of ‘long-pod’ variety mature in late winter to early spring. The more widespread nature of the ‘short-pod’ variety could potentially be due to a preference for this variety as an ornamental plant, due to its more presentable foliage characteristics and shorter pods, in contrast to the ‘long-pod’ variety.

Significant features of the epidemiology of equine influenza in Queensland, Australia, 2007.

An outbreak of equine influenza (EI) caused by influenza A H3N8 subtype virus occurred in the Australian states of Queensland and New South Wales in August 2007. Infection in the Australian horse population was associated with the introduction of infection by horses from overseas. The first case of EI in Queensland was detected on 25 August 2007 at an equestrian sporting event. Infection subsequently spread locally and to other clusters through horse movements prior to the implementation of an official standstill. There were five main clusters of infected properties during this outbreak and several outliers, which were investigated to find the potential mechanism of disease spread. To contain the outbreak, Queensland was divided into infection status zones, with different movement controls applied to each zone. Vaccination was implemented strategically in infected areas and within horse subpopulations. Control and eventual eradication of EI from Queensland was achieved through a combination of quarantine, biosecurity measures, movement control, rapid diagnostic testing and vaccination.

Fishing power increases continue in Queensland's east coast trawl fishery, Australia

The Queensland east coast trawl fishery is by far the largest prawn and scallop otter trawl fleet in Australia in terms of number of vessels, with 504 vessels licensed to fish for species including tiger prawns, endeavour prawns, red spot king prawns, eastern king prawns and saucer scallops by the end of 2004. The vessel fleet has gradually upgraded characteristics such as engine power and use of propeller nozzles, quad nets, global positioning systems (GPS) and computer mapping software. These changes, together with the ever-changing profile of the fleet, were analysed by linear mixed models to quantify annual efficiency increases of an average vessel at catching prawns or scallops. The analyses included vessel characteristics (treated as fixed effects) and vessel identifier codes (treated as random effects). For the period from 1989 to 2004 the models estimated overall fishing power increases of 6% in the northern tiger, 6% in the northern endeavour, 12% in the southern tiger, 18% in the red spot king, 46% in the eastern king prawn and 15% in the saucer scallop sector. The results illustrate the importance of ongoing monitoring of vessel and fleet characteristics and the need to use this information to standardise catch rate indices used in stock assessment and management.