Historic failures of fisheries is driving changes in their management. A broader array of data sources is increasingly being used, typified by the 'weight of evidence' approach used to manage demersal fish populations in Western Australia. These data sources vary considerably in the type and quality of information and potentially provide a more robust understanding when used together.

One novel source of data that has only recently come to the fore, but which holds considerable potential, is passive acoustics - the interpretation of fish noise to gain a broad range of data often impossible to gather by other means. The usefulness of passive acoustics was recently demonstrated in FRDC Project 2004/051 with Mulloway in the Swan River of Perth, WA.

This proposal aims to further develop passive acoustic techniques using Mulloway aggregations in Western Australia. This species highlights the need for non-extractive observations as the species suffers from barotrauma and handling stress (which increases vulnerability to fishing). In addition, this study aims to assess the potential for using passive acoustics on a variety of other key indicator species, including the Western Australian Dhufish and Snapper which are biologically and ecologically likely to be vocal.

In NSW, inherent variation among the characteristics of different estuarine fisheries has resulted in a range of physical modifications designed to improve the selectivity of conventional gears. While some of these designs have been effective in reducing the bycatches of unwanted species by up to 95%, rates of reduction more commonly range between 30 and 70%. Such reductions have obvious benefits for the stocks of bycatch species. considering the magnitudes of bycatches in many estuarine fisheries, and especially those targeting prawns (i.e. often 1000s of fish per haul), it is apparent that despite the use of modified gears, in nearly all cases there still remains some capture and mortality of unwanted individuals.

To augment the post-release survival of unwanted bycatch throughout nearly all of NSW estuarine fisheries (including those involving static gears, where no BRDs have been developed), ancillary options within the second category of input controls (listed above in B2) need to be investigated. The sorts of modifications that warrant examination include, defined soak times for gears, devices to limit predation on discarded bycatch, netting materials in codends that reduce damage to bycatch, the use of gloves to handle bycatch, and the utility of separating target and bycaught species in water after capture.

The majority of these operational and/or post-capture handling procedures have NOT been examined, but have the potential to significantly reduce the remaining impacts of commercial fishing gears on non-target species and sizes in NSW’s estuaries. This is one of the main research priorities detailed in the Fishery Management Strategy for the NSW Estuary General Fishery and comprises a key category within the 2004-2007 Strategic Research Plan for Fisheries, Aquaculture and Aquatic Conservation in NSW. Quantification of the utility of this category of input controls would also have benefit and application throughout all other coastal fisheries in Australia.

The research will form the basis of a PhD candidature. This approach is justified because (i) the work is new and there is sufficient intellectual content to support a PhD student, (ii) there is a paucity of researchers with higher degrees working in the applied fields of gear technology and bycatch mitigation in Australia and (iii) previous, similarly-structured FRDC projects (e.g. 93/180 and 2001/031) have resulted in successful PhD candidatures by project staff. Specifying a PhD candidature formalizes what would already occur if funding was sought for a Fisheries Technician, but at approx. 1/3 the cost, while attracting a substantial in-kind contribution from affiliated institutions (the National Marine Science Centre and University of New England).

Temperate marine fish farmers in Australia seek to have the option to choose between several species of fish based on market price, availability and cost of fingerlings and health and feeding costs. This need was identified at the Aquafin CRC workshop held in 2002 (Allan, 2003). Most research on temperate marine finfish has been conducted on snapper (Pagrus auratus) but farmers are now concentrating more on yellowtail (Seriola lalandi) and mulloway (Argyrosomus japonicus) with significant interest in yellowfin bream (Acanthopagrus australis). Applied research is needed, particularly on the major cost areas of diets and feeding (for both fingerlings and grow-out fish) to help ensure profitability and to give farmers and feed manufacturers information so they can make informed business decisions.

Costs of feeds and feeding are usually the largest budget expense for marine fish farms and also significantly affect costs of producing fingerlings in hatcheries. In hatcheries, the global shortage of Artemia and the huge cost of weaning diets has led to a increased priority for better and cheaper live feeds, formulated weaning diets and feeding strategies. For grow-out, most farmers want high-performance, low-cost feeds. Given a choice, most farmers will pay more for diets to achieve better performance but have no real way to make decisions to achieve the most cost effective feeding strategy. There is a clear lack of information for most temperate marine species about the nutritional specifications needed for high performance diets and what physical characteristics are most desirable in the pellets (e.g. should pellets be floating or sinking, how important is pellet hardness, etc). This prevents feed manufacturers providing data-based recommendations about the best diets for farmers and prevents them from formulating and manufacturing specific diets for temperate marine finfish farmed in Australia. Unfortunately, the same lack of information is restricting choices about the ingredients being used in diets. Almost no information exists about digestibility or utilization of most of the ingredients available for use in Australia aquafeeds. Most farmers are aware of “problems” with the use of terrestrial animal protein meals in animal feeds and that use of such ingredients might negatively affect the export market for their fish. However, apart from research with snapper (Aquafin CRC; WA Fisheries) and barramundi (FRDC ADD Subprogram; WA Fisheries) there is no information about digestibility or utilization of Australian ingredients for temperate marine finfish being farmed in Australia. The immediate result of this lack of information is an increase in the proportion of expensive, imported fishmeal being used in diets.

This project will extend the successful research approach adopted for snapper in Aquafin CRC Project 1B.3-2001/208 (Increasing the profitability of snapper farming by improving hatchery practices and diets). In that project, fingerling costs were reduced by approximately 30% through systematic research to develop more cost-effective hatchery procedures including the demonstration of the feasibility of replacing live feeds including artemia with alternative live feeds (copepods) and/or commercially available, inert pellet diets for advanced snapper larvae. Previous work with snapper also demonstrated a major improvement in growth of juvenile snapper when the optimal feeding frequency and day-length were identified. This project seeks to reduce feed costs, to optimise feeding efficiency and to improve fingerling survival and growth of mulloway and yellowtail. Sub-optimal performance of marine fish larvae is often a result of inadequate nutrition or sub-optimal physio-chemical variables during larval rearing. A high percentage of slow-growing or stunted fish in larval rearing runs can seriously reduce economic viability of hatcheries and increase farming costs. The performance of larvae has not been addressed in a systematic manner and although the commercial hatcheries in SA report that fingerling production is not a barrier, there are no published methods of how to optimize production of fingerlings (i.e. to to increase cost-effectiveness of fingerling production). This lack of information will reduce the chance of expanding marine fish farming in NSW and other states in Australia.

Existing grow-out diets used for marine fish such as yellowtail, mulloway and bream are based on generic formulations for “marine fish” (including salmon and barramundi). These diets produce results but it is unknown if current diets are nutritionally adequate, especially for rapidly growing fish. Even basic requirements, like the best protein to energy ratio, are unknown for yellowtail and mulloway. Both low and high energy diets are available for salmon and barramundi but even simple comparisons to find the best of these two “options” have not yet been carried out. There is no reliable information on ingredient digestibility making it impossible for feed manufacturers to confidently formulate diets with alternative protein sources to fishmeal when fishmeal is hard to obtain and when prices are high (and, of course, fish meal prices continue to rise). Research to provide this information is urgently needed.

There are obvious problems with a "one-species at a time" approach to diet development research. This is expensive and takes a long time. This application seeks to conduct specific research with mulloway and kingfish and to build comprehensive models of nutritional requirements for these two species that can be directly compared with other similar models now available for other marine and freshwater aquaculture species (e.g. snapper, sea bream and barramundi).

Fingerling costs for mulloway and kingfish are currently estimated at $0.60->$2.00/fingerling. These represent well in excess of 10% of operating costs. We aim to reduce these costs by as much as 50%. Growout feeds can cost in excess of $2,000/t and with the costs of feeding are usually in excess of 30% of total operating costs (>50% for some operations). Food conversion ratios of in excess of 1.5:1 are regularly reported. We aim to produce diets with FCRs of 1.2:1 with approximately 25% lower ingredient costs. Together these represent the major areas where improvements in production technology can improve the profitability of marine fish farming.

Preliminary estimates indicate that South Australia's inland/estuarine commercial fishers may be missing out on $3.5-24.5million annually from their relatively static finfish production, representing 67%-540% of the current domestic landed value - all from the lack of a readily available, robust live transport technology! This likely translates to proportionately greater export losses nationally - and missed Industry earnings for reinvestment. At the same time, experts (see FRDC Project Report 92/125.26) indicate much research is already complete. However, for Australian inland/estuarine finfish, no well evaluated and packaged system exists to make live export marketing happen now.

Despite the massive value-adding success from export of quality marine fish products to high demand Asian and other overseas markets, Australian freshwater parallels have not been developed. Production potential from freshwater and estuarine wild capture fisheries has limited capacity to expand, therefore, industry profitability incentives must focus on obtaining greater return on sustainable harvest. Australian freshwater and estuarine fishes are consistently and depressingly undervalued relative to equivalent species on overseas markets (eg, black bream seldom exceed $14A/kg on the South Australian market despite a 96% reduction in harvest since the 1970's while the almost identical Japanese or sea bream, Acanthopagrus latus, regularly returns $45US/kg in Asian metropolitan markets).

Concurrently, development of aquaculture capacity for these same freshwater and estuarine species lags behind higher return marine counterparts due to inadequate profit incentives. This is particularly evident given that similar species worldwide are typically more robust to culture conditions and therefore first to be cultured.

Successful development and transfer of live shipping technology for key Australian freshwater and estuarine species to both wild capture and aquaculture industries has the capacity to overcome these current limitations. Live marketing of wild production can harvest export value, increase profitability per unit production, and provide an identical mechanism for development of a parallel domestic market. Typically, export initiatives provide extremely strong incentives for continuous improvement of product quality. Success in a foreign market also provides excellent protection of our home markets through competitive advantage. The profit incentive of elevated prices domestically and abroad will necessarily spur development of cultured production of these same species.