The research proposed here has received consistantly strong support from the TSGA, The TasFRAB, the Atlantic Salmon Aquaculture Subprogram and the Aquaculture Nutrition Subprogram. The research addresses two Challenges in the FRDC R&D Plan 2000-2005:
Challenge 2 Increasing production through aquaculture (FRDC R&D Plan 2000-2005) is addrssed by this research. The research proposed contributes by increasing understanding of how to increase production under Australian environmental conditions and how to increase efficiency.
Challenge 5 Reducing the quality of fish protein fed to aquatic livestock (FRDC R&D Plan 2000-2005). The proposed research contributes by increasing understanding of processes that drive growth efficiency.

It must be stressed that the research proposed here has been developed in collaboration with Skretting and this means that results will impact on aquafeeds rapidly and in a meaningful way. However, the data generated will be disseminated for use by other feed manufacturers, the aquaculture industry and other researchers.

Tactical Needs
The proposed research aims to demonstrate which feeds are most appropriate for use at the different temperatures experienced by both the salmon and barramunid aquaculture industry during the normal production cycles and over the geographical range they are farmed. The research has to be conducted in Australia because the performance of Atlantic salmon at high temperatures is not important in Northern Europe and the performance of barramundi at low temperatures important is not relevant in South East Asia. Consequently, it is unlikely that commercially driven research of relevance to Australian conditions will be conducted outside of Australia. The vital importance of understanding the relationship between dietary protein and energy in relation to temperature and low growth has been very clearly identified by individual Salmonid growers and by the TSGA for several years. However, farm data cannot be used to solve the issues retrospectively and a clear need for controlled experiments exists. Barramundi aquaculture is expanding rapidley across Australia and they are being farmed under many different environmental (temperature) regimes, there is a clear need to understand the relationship between dietary protein and energy in relation to temperature. In addition to providing direct information about the performance of both species of fish in relation to diet composition the experiments are designed so that data can be incorporated into "factorial models" of growth. These are used by feed companies as well as under development by key researchers. The proposed research will make an important contribution to the data base for these and for both species.

Strategic Needs
The research seeks to address the lack of information about mechanisms that determine efficient growth in fish by consideration key physiological and nutritional variables in relation to temperature. The PI has an extensive record of uses physiological tools to investigate amino acid (protein) and energy utilisation by fishes. Developing this approach in realtion to temperature is of strategic importance for equiping Australian aquaculture with tools to investigate other species. Protein synthesis is a major driver of growth but it is energetically expensive (20-40% of costs of growth)and understanding the interaction between diet composition and efficient growth is a major driver behind the proposed research. The research will develop physiological tools using barramundi as a model, these will then be tested and deveoped further using salmon.

Tasmania in 2005/06 was the largest producer of mussels in Australia; 31% of production and 42% of dollar value. This represents a three-fold increase in production and value of mussels in Tasmania over the past three years. Further to this, Spring Bay Seafoods is Australia largest mussel producer and processor; with consider capital investment into mussel production and processing. This project will directly address the issues of high and unpredictable mortality rates of blue mussel seed during the early nursery phase. There is a need in the hatcheries to develop techniques and approaches that maximise production of quality mussel seed, through informed decisions about how physical and biological conditions in the hatchery affect the health and growth of spat.

World-wide, mussel aquaculture ventures are largely supported by collection of wild juveniles. Several commercial shellfish hatcheries, in USA and Australia, produce small numbers of juvenile mussels to supplement wild collections. Until recently the demand and value of mussels has been too poor to warrant large scale hatchery production, and most shellfish hatcheries focus on higher value species, or species for which wild collection of juveniles is not possible, eg introduced oysters. Collection of spat from the wild imposes critical limits to the capacity of the mussel aquaculture industry to increase production and to control product quality and timing of supply to markets. Reliance on wild spat leaves the industry vulnerable to recruitment failure and restricts production to seasonal availability. In recent years there has been insufficient wild spat settlement to meet the demands of the expanding Tasmanian aquaculture mussel industry. The only way that the mussel industry can begin to compete against imported products and allow Australian consumers access to Australian product is through reliable hatchery production of quality-assured spat.

Strategic plan
This proposal is part of FRDC Industry Development Program, Strategy - Aquaculture development - production and production systems. However, it also has strong capacity building elements, including training of at least one PhD student in the area of fish health/immunology and providing workshops for industry and researchers (Use of immunostimulants in finfish culture, Immune response in fish). It provides leadership development by having a full time young researcher (CI - Dr Richard Morrison) working on this project. Thus, this proposal will significantly contribute to Human Capital Development Program, Leadership and Vocational Development. Improved knowledge of immune response and immunomodulators was identified as one of the key research areas for aquatic animal health in Research and Development Plan Aquatic Animal Health Subprogram. Priorities covered by this key research area included immunology in aquatic vertebrates (nature of disease and host-pathogen interactions), immunomodulators (aquatic animal health management) and development of tools for immune status monitoring as a means of implementing health management strategies (surveillance and monitoring). All three elements are included in this proposal. This proposal is consistent with R&D plans for Atlantic Salmon Aquaculture Subprogram and with Aquafin CRC AGD research program. It also addresses targeted priority: fish health, within Program 2: Industry Development, Key R&D issues for fisheries and aquaculture in SA, South Australia's Fisheries and Aquaculutre Research and Development Strategy 2002-2007. The research focus is within Tasmanian Fisheries and Aquaculture, Aquaculture Strategic Research Plan 1999-2004. This proposal fits well into Aquafin CRC strategy and mission by significant contribution of its outcomes to achieving sustainable aquaculture in Australia through reduction of economic impact of diseases in farmed fish, development of environmentally friendly approaches to disease management and training aquaculture industry and researchers in the fields of fish immunology.

Need for research
It is impossible to prevent the presence of pathogens in aquaculture systems, particularly in sea-cage grow-out. Most disease outbreaks occur when there is an interaction between pathogens and susceptible fish (for example immunocompromised fish due to stress). This will result in lowering the performance of the fish and possibly mortalities. Sustainable aquaculture of finfish requires lowering the risk of disease outbreaks and replacing disease treatment with control strategies. The use of immunomodulators is essential to achieve these goals, in particular in times of increased disease risk or reduced immunocompetence. Our understanding of host-pathogen interactions and immune response allows for the use of appropriate immunomodulators. For example, if a disease is caused by overreaction of the inflammatory response, traditional immunostimulants will not improve the outcomes. Similarly, there is a need to determine correct timing and dose for immunomodulation in mariculture. Improved immune response would improve fish performance during grow-out.

Importantly immunomodulators are natural products that are derived from microbes, thus avoiding the use of chemical products. Commerical immunomodulators have been successfully used in aquaculture worldwide however only experimentally in Australia. For example oral immunomodulators MicroVital significantly increases survival rates of Atlantic salmon following Vibrosis challenge and 32% gain in survival rates of salmon fed natural immunomodulators (ß glucans and nucleotides) following exposure to IPN (exotic viral disease) challenge has been achieved in trials in Norway. However, there is little information available for fish species other than salmon or diseases other than commercially important in Northern Hemisphere. There is a need to develop immunomodulation strategies that are directly applicable to Australian mariculture, either specific for our species or diseases affecting Australian aquaculture industry (for example Amoebic Gill Disease) or unique conditions such as water temperatures.

Benefits
For Atlantic salmon we will address AGD management by investigation of immunomodulators. AGD is the main health problem for salmon industry and successful use of immunomodulation could provide an answer, particularly in combination with other management strategies.
This project is generic and the benefits are not limited to the species we will use as a model in our investigation. Other finfish aquaculture industries will also benefit from training and workshops provided by this project.