TSGA IPA: Comparative susceptibility and host responses of endemic fishes and salmonids affected by amoebic gill disease in Tasmania
Atlantic salmon aquaculture in Tasmania continues to expand with production exceeding 25000 tonne for 2007-08 representing a 10000 tonne increase over the last five years. Directly employing over 1200 people (26), the Tasmanian industry is well placed for further growth due to its proximity to Asian markets. Tasmania’s climate provides ideal temperatures for Atlantic salmon production resulting in fast growth, substantially reducing the time to harvest (compared to European producers). The Tasmanian salmon industry plans to double production in the next five years, an ambition that may be problematic considering that current sites are nearly fully developed. New farming zones may need to be established in less sheltered waters (26), further from land and away from freshwater sources. Future reliability on FW sources in conjunction with the current high costs for treating AGD demonstrates a clear need for providing cost effective, efficacious alternatives that reduce the reliance upon freshwater resources. Progressing to alternative treatment strategies for AGD has proven elusive and (according to the recent AGD research review) has been attributed to fundamental knowledge deficiencies of host-pathogen interactions and epidemiology.
This proposal aligns specifically with TSGA R&D priorities within the fish health tactical development area those being “AGD-Epidemiology/Patho-biology” and “AGD-Comparing the response/mechanisms of salmon to native fish”. The proposed research also aligns with the TSGA’s “areas of interest” for 2011 specifically “AGD-comparing response between salmon and trout”.
Final report
Abalone Aquaculture Subprogram: a national survey of diseases of commercially exploited abalone species to support trade and translocation issues and the development of health surveillance programs
Abalone Growers Associations in Victoria, Tasmania and South Australia have given their support for the establishment of health monitoring programs of their farm’s stock, and are willing to contribute financially for establishing these and for ongoing monitoring. They see such programs as putting them in a unique position to to enable them to prevent disease in their stock and of meeting future market expectations in relation to health accreditation. This process is threatened by inadequate data on diseases in wild stock, and in some states by limited experience in abalone diagnosis.
Similarly the wild harvest abalone industry recognises vulnerability from a lack of knowledge of the occurrence and distribution of diseases in Australian wild stocks, in a climate where interstate translocation and trade access and quality issues are increasing. They also seek assurances on the health of farmed stock and of stock used for reseeding operations. As a result, the wild abalone sector and fisheries and animal health authorities in these states also strongly support a baseline survey of diseases present in the exploited abalone species, and development of improved surveillance capability.
The project is to acquire this background data on abalone disease, by a health survey covering the natural range of the exploited temperate abalone species. It includes the abalone aquaculture industry and the wild fishery in SA, Victoria, Tasmania, NSW and WA. The project will incorporate associated initial training, permanent presentation on collated results in accessible electronic format (CD and the subprogram’s website), and an abalone disease symposium to develop a net-work of state-based resources for on-going diagnosis, health certification and other shellfish health related functions at reasonable cost to the industry.
Development of the on-going state-based surveillance programs for aquaculture will progress in conjunction with this (without cost to the project), and with consultation with wild fisheries industries and managers, who will also benefit from improved capability for diagnostic and surveillance services.
Final report
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.
Indigenous business development opportunities and impediments in the fishing and seafood industry - 'Wave to plate' establishing a market for Tasmanian cultural fisheries
Aquafin CRC - Atlantic Salmon Aquaculture Subprogram: environmental control of growth and early maturation in salmonids
Aquafin CRC - Atlantic Salmon Aquaculture Subprogram: host-pathogen interactions in Amoebic Gill Disease
This project will develop methods and provide information for vaccine and novel treatment development. For example, techniques for the isolation and maintenance of N. pemaquidensis are based on monoxenic cultures. This culture is highly problematic because preparations of protozoa are contaminated with bacteria. Studies to determine cell function, protein and DNA composition have been seriously compromised by the bacteria. Culture relies on the use of agar. Cell propagation and harvesting by this system is time consuming and inefficient. Development of practical systems for cell factory production of N. pemaquidensis is required. This is important for studies of cell wall composition and cell function, which require considerable biomass. There is no model of infection using protozoa derived from monoxenic or xenic cultures. This represents a major limitation, particularly when it is necessary to use controlled doses of a single strain. Current methods rely on the use of N. pemaquidensis harvested from infected fish. While this strategy meets an immediate need, long-term it cannot be justified. Development of a method to grow in vitro virulent protozoa capable of infecting fish is an essential objective. The current library of N. pemaquidensis isolates obtained from fish with AGD is small and in continuous culture for almost 10 years. There is an urgent need to re-isolate N. pemaquidensis and expand the library to ensure an adequate range of phenotypes and genotypes. Preservation of N. pemaquidensis is an essential requirement of the AGD programme as it will maintain strain integrity, a vital objective for vaccine development. The complexity of growing N. pemaquidensis has proved a major limitation to studies on AGD. A centre of expertise in the culture of N. pemaquidensis should result in guaranteed supply of organism. A reference laboratory will ensure standardisation of cultures and uniformity of research outcomes.