Health and Performance of Ranched Southern Bluefin
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HEALTH AND PERFORMANCE OF RANCHED SOUTHERN BLUEFIN TUNA NICOLE TERESA KIRCHHOFF, MSC Submitted in fulfillment of the requirements for the degree of Doctor of Philosophy University of Tasmania (August 2012) National Centre for Marine Conservation and Resource Sustainability Launceston, Tasmania Australia DECLARATION OF ORIGINALITY This thesis contains no material which has been accepted for a degree or diploma by the University or any other institution, except by way of background information and duly acknowledged in the thesis, and to the best of my knowledge and belief no material previously published or written by another person except where due acknowledgement is made in the text of the thesis, nor does the thesis contain any material that infringes copyright. STATEMENT REGARDING PUBLISHED WORK & AUTHORITY OF ACCESS The publishers of the papers comprising Chapters 2 thru 6 hold the copyright for that content, and access to the material should be sought from the respective journals. The remaining non published content of the thesis may be made available for load and limited copying and communication in accordance with the Copyright Act 1968. STATEMENT OF ETHICAL CONDUCT The research associated with this thesis abides by the international and Australian codes on human and animal experimentation, the guidelines by the Australian Government’s Office of the Gene Technology Regulator and the rulings of the Safety, Ethics and Institutional Biosafety Committees of the University. All work with animals, samples and methods for recovering samples were approved by the University of Tasmania board of animal ethics, project number A0010593. Signed: Date: ii STATEMENT OF CO-AUTHORSHIP The following people and institutions contributed to the publication of the work undertaken as part of this thesis: [Chapter 2]: Kirchhoff, N.T., Antignana, T.D., Leef, M.J., Hayward, C., Wilkinson, R.J., Nowak, B.F., (2011). Effects of immunostimulant on ranched southern bluefin tuna T. maccoyii: immune response, health, and performance. Journal of Fish Biology 79: 331-355. Candidate: N.T. Kirchhoff, Author 1: T.D. Antignana, Author 2: M.J. Leef, Author 3: C. Hayward, Author 4: R.J. Wilkinson, Author 5: B.F. Nowak Author 1 organized the logistics for the injections of immunostimulants and vitamins, supervised the injector during the project, assisted with collection of samples, and analyzed the vitamin content within samples. Author 2 assisted with collection of samples, offered assistance in the laboratory, and assisted with refinement and presentation of research results. Author 3 assisted with collection of samples, completed all parasite counts and parasite statistical analysis. Author 4 analyzed the cortisol content of samples. Author 5 contributed to the idea, its formalization and development, helped organize sampling logistics and assisted with refinement and presentation of research results. Authors 1 thru 5 assisted with editing of the final manuscript. [Chapter 3]: Kirchhoff, N.T., Leef, M.J., Ellis, D., Purser, J., Nowak, B.F., (2011). Effects of the first two months of ranching on the health of Southern Bluefin Tuna Thunnus maccoyii. Aquaculture 315: 207-212. iii Candidate: N.T. Kirchhoff, Author 1: M.J. Leef, Author 2: D. Ellis, Author 3: J. Purser, Author 4: B.F. Nowak Author 1 assisted with collection of samples, offered assistance in the laboratory, and assisted with refinement and presentation of research results. Author 2 contributed to the idea, its formalization and development and helped organize sampling logistics. Author 4 contributed to the idea, its formalization and development, helped organize sampling logistics, and assisted with refinement and presentation of research results. Authors 1 thru 4 assisted with editing the final manuscript. Chapter 4: Kirchhoff, N.T., Rough, K.M., Nowak, B.F., (2011). Moving cages further offshore: effects on southern bluefin tuna, T. maccoyii, parasites, health, and performance. PLoS ONE 6(8): e23705. Candidate: N.T. Kirchhoff, Author 1: K.M. Rough, Author 2: B.F. Nowak Author 1 assisted with collection of samples at harvest. Author 2 contributed to the idea, its formulization and development, helped organize sampling logistics, and assisted with refinement and presentation of research results. Authors 1 and 2 assisted with editing the final manuscript. Chapter 5: Kirchhoff, N.T., Leef, M.J., Valdenegro, V., Hayward, C.J., Nowak, B.F., (2012). Correlation of humoral immune response in southern bluefin tuna T. maccoyii with infection stage of the blood fluke, Cardicola forsteri. PLoS ONE, submitted. iv Candidate: N.T. Kirchhoff, Author 1: M.J. Leef, Author 2: V. Valdenegro, Author 3: C.J. Hayward, Author 4: B.F. Nowak Author 1 assisted with collection of samples, offered assistance in the laboratory, and assisted with refinement and presentation of research results. Author 2 and Author 3 assisted with collection of samples and completed some of the parasite counts within the samples. Author 4 contributed to the idea, its formulation and development, and assisted with refinement and presentation of research results. Authors 1 thru 4 assisted with editing the final manuscript. Chapter 6: Kirchhoff, N.T., Leef, M.J., Nowak, B.F., (2012). An analysis of two management strategies for a blood fluke Cardicola forsteri infection in ranched Southern Bluefin Tuna Thunnus maccoyii. PLoS ONE, submitted Candidate: N.T. Kirchhoff, Author 1: M.J. Leef, Author 2: B.F. Nowak Author 1 assisted with collection of samples. Author 2 contributed to the idea, its formulization and development, helped organize sampling logistics, and assisted with refinement and presentation of research results. Authors 1 and 2 assisted with editing of the final manuscript. v We the above undersigned agree with the above stated “portion of work undertaken” for each of the above published (or submitted) peer-reviewed manuscripts contributing to this thesis: Signed: Date: (Professor Barbara Nowak) Supervisor NCMCRS University of Tasmania Signed: Date: (Assoc. Professor John Purser) Head of School NCMCRS University of Tasmania vi ABSTRACT The Australian southern bluefin tuna (SBT) industry is continually looking for ways to improve fish health within the ranching environment, both for increased profitability and concern for animal welfare. This thesis utilized current and newly acquired knowledge about southern bluefin tuna health to make educated manipulations of their ranching environment and/or husbandry practices. SBT health, parasites and performance where then monitored as a measurement of success. Five major projects were completed, all projects completed on the commercial scale. Three projects focused on environmental and/or husbandry manipulations: (chapter 2) dietary supplementation of immunostimulants and vitamins; (chapter 4) moving cages further offshore; (chapter 6) an assessment of two management strategies for blood fluke, Cardicola forsteri, infection. While two projects aimed to gain more information about ranched SBT health: (chapter 3) a detailed description of the first two months of ranching; (chapter 5) correlation of SBT humoral immune response with infection stage of C. forsteri. Greater knowledge was obtained relating to the effects of ranching. Over the first two months, weight, length, condition index, hemaoglobin concentration, and immune response were all found to change significantly. Ranched SBT were found to acclimate to ranching within one month post transfer and were relatively healthy prior to an acute mortality event from week five to seven of ranching, which resulted in a cumulative mortality of 8.5%. The mortality event was associated with decreased hemaoglobin concentrations and changes in immune response. Additional information was also gained on one of the most common and significant infections during ranching, blood fluke Cardicola forsteri. The timeline for C. forsteri infection was validated using natural infections in SBT. Humoral immune response (i.e. lysozyme, alternative complement and specific antibody activity) was correlated to infection and was found to develop concurrently with C. forsteri. The majority of physiological response coincided with commencing egg production, at approximately 5 to 7 weeks of ranching. New and previous knowledge regarding C. forsteri infection in SBT were merged, resulting in a inclusive infection, physiological response and diagnosis timeline. ABSTRACT 2 Further enhancement of ranched SBT health and performance was also obtained within this thesis utilizing dietary supplementation, adjustments in ranching location, and chemotherapeutics. Supplementing the diet of ranched SBT for the first twelve weeks with Vitamins E and C resulted in 1.5 times higher lysozyme activity at 8 weeks of ranching. Vitamin supplementation was also associated with tow specific improvements in performance, including enhanced survival, decreased Cardicola forsteri prevalence and intensity, and enhanced alternative complement activity. No changes in health, immune response, and performance were associated with immunostimulant supplementation. Examination of the feasibility of offshore ranching yielded significant effects on the health and performance of ranched SBT. Compared to SBT ranched in the traditional near shore environment, SBT ranched further offshore had enhanced survival, increased condition index at 6 weeks of ranching, and superior health. The offshore cohort had no C.forsteri and a 5% prevalence of Caligus spp. compared to a prevalence of 85% for C. forsteri and