Seafood CRC: addressing roadblocks to the adoption of economics in fisheries policy (2013/748.20 Communal)
Dependence of commercially import fish on krill as a food source in south-east Tasmania
Final report
This final report on the project describes data on stomach contents of major fish predators of the euphausiid Nyctiphanes australis.
The study has concluded that: size and stock of krill and its production can be calculated with some degree of confidence; major predators of adult krill can be identified though the greatest mortality, which occurs in the larval stages, is probably due to carnivorous zooplankters; and swarming by krill is of extreme importance in increasing the attraction of krill as food.
Aquafin CRC - Atlantic Salmon Aquaculture Subprogram: control of precocious sexual maturation in Atlantic salmon
There are two major aspects:
1. Importance to industry of control of precocious sexual maturation
Tasmanian salmon typically mature after only one winter at sea, in contrast to northern- hemisphere populations where the majority take two ‘sea-winters’ to mature. The Tasmanian fish still reach 3 – 5 kg during this period due to the favourable effects of higher temperature on growth, however, the less desirable outcome of early maturation is the compression of the harvest season. Strategies designed to improve seasonal production have been estimated to be worth $A 8 – 16 million per year to the Tasmanian salmon industry (confidential industry estimate prepared for CRC for Aquaculture in 1998).
2. Requirement to conduct research in Tasmania
Functional photoperiod manipulation techniques have been developed overseas so why do it in Tasmania rather than simply import solutions? Overseas protocols have been trialled by the Tasmanian industry but have given negative or unpredictable results. Confounding factors which require consideration before overseas protocols can be applied successfully and predictably in Tasmania are:
A. Light intensity.
Due to Tasmania’s low latitude and high number of sunshine hours relative to the majority of northern hemisphere salmon farming areas, it is likely that salmon farmed in Tasmania are exposed to higher daytime light intensities, particularly at the equinoxes. Relative light intensity is a critical factor for the success of photoperiod manipulation practices and it is expected that higher, yet to be determined, levels of nighttime illumination will be required under Tasmanian conditions.
B. Temperature.
Overseas scientists report increased melatonin secretion (up to approx. 30%) at summer temperatures relative to winter temperatures in Atlantic salmon maintained under identical photoperiods. Tasmania’s relatively high water temperatures suggest that a further increase in light intensity will be required to reduce plasma melatonin levels below the putative threshold required to ensure that the fish perceive any modification to photoperiod.
C. Seasonal and individual variation.
Assuming that the preceding factors can be adequately clarified, it will be necessary to account for the possible effects of differences between seasons (both within and between years) and individual variation within fish populations in relation to the response of stocks to photoperiod manipulation. Relative to overseas salmon farming areas, Tasmania tends to have a short, mild winter, an early, warm spring and a long, hot summer. Thus timing of the critical “gate-open” decision period for maturation has yet to be determined under Tasmanian conditions.
Final report
Impact of gillnet fishing on inshore temperate reef fishes, with particular reference to banded morwong
Final report
Aquafin CRC - Atlantic Salmon Aquaculture Subprogram: establishment of challenge for AGD
Strategic plan
This proposal is part of the FRDC Industry Development Program, Strategy – Aquaculture Development – Production and Production Systems. The project includes a technician and a postdoctoral research fellow (Dr Philip Crosbie) as co-investigator and they will both be provided with suitable professional development opportunities through the Education Program of the Aquafin CRC. Later in the project it may be possible to adopt a PhD student with an independent scholarship or include Honours and Masters projects as they are required and become available. Thus, the project will contribute to the Human Capital Development Program, Leadership and Vocational Development. This proposal includes several key research areas outlined in the Aquatic Animal Health Subprogram Strategic R&D Plan, namely the Nature of disease and host-pathogen interactions and Training and capacity building. Relevant priorities being: to provide improved knowledge of the biology of disease agents (in this case the AGD-causing organism), and an improved knowledge of host responses to disease agents which will be partially addressed by monitoring the specific antibody response to N. pemaquidensis antigens (Nature of disease and host-pathogen interactions). Both the research and service components of this proposal will expand the technical skill base in aquatic animal health and facilitate R&D knowledge transfer (Training and capacity building). This project will underpin other projects that contribute to the Aquafin CRC Health Program Outcomes ie. reduced economic impact of disease (AGD) in finfish (Atlantic salmon) farming.
Need for this research
The continued existence of Atlantic salmon farming in Tasmania is threatened by AGD. Production is expected to increase over the next few years and this will undoubtedly lead to an increase in the incidence of AGD. The AGD control method of freshwater bathing has increased in frequency with the growth in production over the past few years and this trend is expected to continue. This will present a growing cost burden to salmon growers, it is therefore imperative that the impact of AGD on the industry be reduced so as to maintain viability for the future. Multidisciplinary teams have been assembled to achieve this outcome via a number of projects. The projects are complementary and in some cases interdependent where progress in one area is dependent on progress in another area. This is particularly the case with the service component of the current proposal and the vaccine development program, where supply of infective material and a means of controlled testing of candidate vaccines are integral to success. Vaccine development requires identification of specific antigens from the pathogen that will elicit a protective immune response in the host, hence the need for significant quantities of infective material. Similarly, success of the treatment of AGD investigation is dependent on supply of cells for initial screening of a battery of potential therapeutants in vitro before attempting field trials. The research component of the proposal, which is the development of a standard AGD challenge method that can be used in experimental tanks, is essential for the success of these projects. We need to be able to consistently induce AGD in fish to economically appraise alternative treatments and candidate vaccines before moving onto costly field trials. Inducing experimental infections is widely recognised as one of the cornerstones of vaccine development (Nordmo, 1996).
Benefits
The major benefit will be enabling progress in the vaccine development and alternative treatment projects to be made. We will have in place a model to economically appraise novel treatments, experimental vaccines and other less specific means of prophylaxis such as immunomodulation. Ultimately the project will contribute to a collective outcome of lessening the impact of AGD on salmon producers and reducing the estimated 10-20% of production costs that is currently spent controlling the disease. Other benefits include a better understanding of risk factors contributing to AGD, and the opportunity to investigate the virulence mechanisms of the organism. Overall the project will contribute to research output and service. The systematic development and subsequent use of challenge models will yield publishable material. The service aspect will be in the supply of amoebae to collaborators and provision of a means to test novel therapeutants, experimental vaccines and immunomodulatory compounds.
References
Nordmo, R., 1996. Strengths and Weaknesses of Different Challenge Methods. In: Fish Vaccinology (ed. By Gudding, R., Lillehaug, A., Midtlyng, P.J. and Brown, F.) Developments in Biological Standardisation. Basel, Karger p 303-309
Final report
This project has increased our knowledge of Amoebic Gill Disease, in particular about the pathogen and the dynamics of infection. We have described a new species of neoparamoeba, Neoparamoeba perurans, and showed that it has been consistently associated with AGD worldwide. Stocking density, acclimation to sea water and amoeba batch variability affected AGD infections. During this project challenge protocols were developed, which have been successfully used and their results correlated well with field challenge. This project provided crucial support for all AGD research through provision of amoebae and salmon for all AGD projects and running experimental challenges for trial vaccines.
The main objectives of this project were to provide essential service for AGD research. During this project we standardised existing AGD challenge protocol and developed a new in vivo gill attachment challenge assay. Both challenge protocols have been successfully applied in AGD research. Research on virulent amoebae resulted in a description of a new species, which consequently has been shown to be involved in all AGD cases worldwide. This discovery led to the development of new diagnostic tests, which are now available for confirmation of AGD infections and further research.
In conclusion, this project has not only provided essential support for all AGD research by supplying amoebae and salmon and running AGD challenges for the experimental vaccines, but also increased our knowledge and understanding of AGD.
Keywords: Amoebic Gill Disease, salmon, aquaculture.
Rock Lobster Enhancement and Aquaculture Subprogram: the feasibility of translocating rock lobsters in Tasmania for increasing yield
Modelling of the Tasmanian lobster resource has indicated that loss of yield through spatial differences in growth of lobsters is greater than 25% of the TACC. Effects of fishing on egg production/recruitment and ecology also appear poorly managed spatially.
Increasing catch targets high priority areas in the strategic plans of each stakeholder. The Tasmanian Government has stated their intent to pursue growth in primary industry as a key strategic area through the “State of Growth” strategy. The project squarely targets all aspects of the University of Tasmania's “EDGE agenda”, particularly through “Engagement” with the community by delivery of a substantial economic benefit. The need for this research has been identified by the commercial and recreational lobster sectors in each strategic plan for crustacean research since the first plan was produced by the CRAG in 1996, specifically under the topics of “stock enhancement” and “translocation”.
Final report
Translocation involves the shifting of undersize rock lobsters to new areas to increase productivity and/or quality of product. We modelled the translocation of rock lobsters from four original sites to four release sites with a range of growth rates.
Most model scenarios led to increases in yield at least double the status-quo. Greatest gain occurred with simulations of the translocation of females from the SW to the NW – in these cases the translocation of 1 tonne led to almost no loss of yield at the origin site but a 1.6 tonne gain at the release site.
Levels of egg production in northern regions are a management issue for the Tasmanian fishery and the model indicated that these would be improved by translocation. Modelling suggested that both yield and egg production benefits would be greatest when smaller females are translocated and when translocation is integrated with increased regional size limits in the north.
Economic modelling of scenarios that involved the movement of five tonnes of lobsters by charter indicated that it is possible to generate an additional kilogram of catch for around $2.60. This compares favourably with current lease costs of over $15/kg. Net state benefit was $160,000 per five tonne trip by a chartered vessel. The internal rate of return for these operations was around 200%, which constitutes an extremely attractive investment.
Three possible systems for funding translocation were developed and each involved an allocation of additional quota to fishers. Translocation appears to offer a feasible option for sustainably and substantially increasing yield by converting low growth, low value lobsters into more productive, higher value lobsters.
Keywords: rock lobster, Jasus edwardsii, translocation, yield increase, sustainable development, bio-economic modelling.