Developments in controlled green-water larval culture technologies for estuarine fishes in Queensland, Australia and elsewhere

Since 1989, researchers with the Department of Primary Industries and Fisheries (DPI&F) in Queensland, Australia, have successfully used controlled low-water exchange green-water cultures to rear the larvae of estuarine fishes and crustaceans through to metamorphosis. High survivals and excellent fry condition have been achieved for several commercially important endemic species produced for various projects. They include barramundi or sea bass, Lates calcarifer, Australian bass, Macquaria novemaculeata, dusky flathead, Platycephalus fuscus, sand whiting, Sillago ciliata, red sea bream or snapper, Pagrus auratus, banana prawn, Fenneropenaeus merguiensis, and others. The consistent success of our standardised and relatively simple approach at different localities has led to it being incorporated into general fingerling production practices at several establishments in Australia. Although post-metamorphosis rearing methods have differed for each species investigated, due to various biological and behavioural traits and project requirements, these larval rearing methods have been successful with few species-specific modifications. Initially modelled on the Taiwanese approach to rearing Penaeids in aerated low-water exchange cultures, the approach similarly appears to rely on a beneficial assemblage of micro-organisms. Conceptually, these micro-organisms may include a mixture of the air-borne primary invaders of pure phytoplankton cultures when exposed to outdoor conditions. Whilst this would vary with different sites, our experiences with these methods have consistently been favourable. Mass microalgal cultures with eco-physiological youth are used to regularly augment larval fish cultures so that rearing conditions simulate an exponential growth-phase microalgal bloom. Moderate to heavy aeration prevents settlement of particulate matter and encourages aerobic bacterial decomposition of wastes. The green-water larval rearing approach described herein has demonstrated high practical utility in research and commercial applications, and has greatly simplified marine finfish hatchery operations whilst generally lifting production capacities for metamorphosed fry in Australia. Its potential uses in areas of aquaculture other than larviculture are also discussed.

Stakeholder expectations for environmental assurance in agriculture: Lessons from the pastoral industry

This paper outlines the expectations of a wide range of stakeholders for environmental assurance in the pastoral industries and agriculture generally. Stakeholders consulted were domestic consumers, rangeland graziers, members of environmental groups, companies within meat and wool supply chains, and agricultural industry, environmental and consumer groups. Most stakeholders were in favour of the application of environmental assurance to agriculture, although supply chains and consumers had less enthusiasm for this than environmental and consumer groups. General public good benefits were more important to environmental and consumer groups, while private benefits were more important to consumers and supply chains. The 'ideal' form of environmental assurance appears to be a management system that provides for continuous improvement in environmental, quality and food safety outcomes, combined with elements of ISO 14024 eco-labelling such as life-cycle assessment, environmental performance criteria, third-party certification, labelling and multi-stakeholder involvement. However, market failure prevents this from being implemented and will continue to do so for the foreseeable future. In the short term, members of supply chains (the people that must implement and fund environmental assurance) want this to be kept simple and low cost, to be built into their existing industry standards and to add value to their businesses. As a starting point, several agricultural industry organisations favour the use of a basic management system, combining continuous improvement, risk assessment and industry best management practice programs, which can be built on over time to meet regulator, market and community expectations.

Parthenium hysterophorus L. (Asteraceae)

Parthenium is a serious problem in several tropical and sub-tropical areas around the world and particularly an emerging problem in southern Africa. It is a Weed of National Significance in Australia. The chapter summarises current knowledge about the taxonomy, biology, distribution, ecology, impacts and biological control of the weed worldwide. Queensland has led attempts to achieve biological control of parthenium since it first began foreign exploration in 1977. Since then nine insects and two rusts have been released in Queensland. Some of these have since been, or will be, used by other countries. The program has brought significant benefits to Queensland through an increase in grass biomass in some areas. Instances of non-target attack by one agent, particularly in India, are discussed with the conclusion that the effects were ultimately negligible and possibly due to parthenium pollen lodging on the leaves of non-target plants. The insects introduced for parthenium have also given a measure of control for the very closely related weeds, ragweed and Noogoora burr. The paper draws a conclusion that local climatic conditions are very important when considering whether a successful agent in one country will be useful in a second country.

Responses of tribolium castaneum to olfactory cues from cotton seeds, the fungi associated with cotton seeds, and cereals

We tested, in an olfactometer, whether or not Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) responds preferentially to the volatiles that emanate from the fungi associated with cotton [Gossypium hirsutum L. (Malvaceae)] seed over those that emanate from cereals, because cereals are usually portrayed as the primary resources of these beetles. Pairwise comparisons were conducted between cotton seed, wheat (Triticum aestivum L.), and sorghum [Sorghum bicolor (L.) Moench] (both Poaceae); volatiles were tested from intact seeds and from both water and ethanol extracts. The results demonstrate that T. castaneum is attracted more strongly to cotton seeds with its lint contaminated with fungi, than to the conventional resources of this species (i.e., wheat and sorghum). Further tests prove that it is the fungus on the lint that produces the active volatiles, because the beetles did not respond to sterilized cotton lint (i.e., without the fungi typically associated with it when cotton seed is stored). Tests with five fungal cultures (each representing an unidentified species that was isolated from the field-collected cotton lint) were variable across the cultures, with only one of them being significantly attractive to the beetles. The others were not attractive and one may even have repulsed the beetles. The results are consistent with the beetles having a strong ecological association with fungi and suggest it would be worth investigating the ecology of T. castaneum from this perspective. © 2012 The Netherlands Entomological Society.

Generalised growth models for aquatic species with an application to blacklip abalone (Haliotis rubra)

This paper presents a maximum likelihood method for estimating growth parameters for an aquatic species that incorporates growth covariates, and takes into consideration multiple tag-recapture data. Individual variability in asymptotic length, age-at-tagging, and measurement error are also considered in the model structure. Using distribution theory, the log-likelihood function is derived under a generalised framework for the von Bertalanffy and Gompertz growth models. Due to the generality of the derivation, covariate effects can be included for both models with seasonality and tagging effects investigated. Method robustness is established via comparison with the Fabens, improved Fabens, James and a non-linear mixed-effects growth models, with the maximum likelihood method performing the best. The method is illustrated further with an application to blacklip abalone (Haliotis rubra) for which a strong growth-retarding tagging effect that persisted for several months was detected. (C) 2013 Elsevier B.V. All rights reserved.