What to feed yellowtail kingfish cultured in cold water? JENNA BOWYER PhD Supervisors A/Prof. Jian Qin Flinders University Dr. David Stone SARDI Aquatic Sciences (SUSTAINABLE FEEDS & FEED MANAGEMENT FOR YELLOWTAIL KINGFISH)

Yellowtail kingfish, Seriola lalandi (YTK) Introduction Clean Seas Tuna (CST) currently produces 5000 Mt yr -1

CST YTK aquaculture sites in SA CST plan to boost production to 10,000 Mt yr -1 Port Augusta Arno Bay Port Lincoln SPENCER GULF

YTK are grown at fluctuating water temps in Spencer Gulf (11-24°C) Water temp (°C)

Production cycle of YTK grown at fluctuating water temps in Spencer Gulf (11-24°C) harveststocking Miss harvest window = loss of productivity Stock fish at 5 g (Oct/Nov) Harvest at 3 - 4kg (1 winter) month production cycle Water temp (°C)

Effects of water temperature on growth Best growth Moderate growth (Shoulder periods) Low or no growth YTK are grown at fluctuating water temps in Spencer Gulf (11-24°C) Water temp (°C)

To improve the condition coming into winter (sub-optimal temperatures, 17-19°C) in an attempt to get better growth coming out of winter to meet harvest schedule Aim Need better understanding of the nutritional requirements of YTK cultured at 17-19°C Shoulder period Water temp (°C)

Objectives Explore baseline growth performance, condition and feed efficiencies for YTK cultured at different water temperatures ranging from 12 to 24°C Determine effective protein: energy ratios for YTK at optimal (24°C) & sub-optimal temperatures (18°C) Replace fish meal & fish oil with sustainable alternative plant & animal protein & lipid sources at optimal (24°C) & sub-optimal temperatures (18°C)

Experimental facilities South Australian Research & Development Institute – Aquatic Sciences Temperature controlled recirculating & flow- through systems –Nutrition laboratory –24 × 700-L fibreglass tanks –Aquarium room –36 × 170-L fibreglass tanks

Experimental facilities Department of Primary Industries, NSW Port Stephens Fisheries Institute –Temperature controlled recirculating & flow through systems Source: Dr. Mark Booth, PSFI, NSW

Experiments

Experiment 1: Growth performance, condition & feed efficiencies of YTK at 12 to 24°C –Location: NSW DPI, Port Stephens Fisheries Institute (PSFI) –Diet : Reference diet (45% protein, 20% lipid) –Fish size: ~500g YTK –Replication: 3 tanks/treatment –Duration: 8 weeks One-factor design Temperature (°C) Aim: Benchmark growth performance of YTK

–Location: SARDI Aquatic Sciences, West Beach SA –Diets: formulated using fish meal & fish oil as the primary ingredients Three-factor design Temperature (°C)1824 Protein level (%)4050 Lipid level (%) Experiment 2a & 2b: Optimum protein: energy ratios for small & large YTK at 18 & 24°C Aim: Determine optimum P:E ratios for YTK Experiment 2a ~5g (initial) YTK 3 tanks/ treatment 4 weeks Experiment 2b ~250g (initial) YTK 2 tanks/ treatment 8 weeks

–Location: SARDI Aquatic Sciences, West Beach SA –Test products: soybean, canola, lupin & poultry (TBD) –Diets: 5 diets to be formulated to contain equal amounts of protein, lipid & energy (TBD) & balanced for lysine & methionine –Fish size: ~5g (initial) –Replication: 3 tanks/treatment –Duration: 4 weeks Two-factor design Temperature (°C)1824 Dietary fish meal protein replacement level (%) Experiments 3 & 4: Evaluation of alternative protein sources at 18°C & 24°C Aim: Investigate the suitability of sustainable alternative protein sources to replace fish meal for YTK

–Location: SARDI Aquatic Sciences, West Beach SA –Test products: canola oil & poultry fat (TBD) –Diets: test products to replace fish oil in dietary formulation –Fish size: small fish ~5g –Replication: 3 tanks/treatment –Duration: 4 weeks Two-factor design Temperature (°C)1824 Dietary fish oil replacement level (%) 050:50100 Experiments 5: Alternative lipid sources (canola oil, poultry fat) at 18°C & 24°C Aim: Investigate the growth performance of YTK when fed sustainable alternative lipid sources to replace fish oil

Sample analysis Growth performance/ condition/ feed efficiency –Specific growth rate (%BW/ day), daily feed intake, feed conversion ratio, condition index, protein & energy retention efficiencies, fillet yield, hepatosomatic index Apparent digestibility coefficient (ADC) –Run after completion of growth trial –Faeces will be collected by manual stripping –Proximate composition of faeces and diets Fillet fatty acid composition –product quality Proximate composition –Nutrient retention efficiencies & product quality Lipid oxidation (liver) –Thiobarbituric acid reactive substances (TBARS) –Vitamin E

Sample analysis Gut bacterial flora –Identify the bacterial communities in the anterior & posterior gut sections, using Terminal Restriction Fragment Length Polymorphism (TRFLP) Histology –Identify any physical changes in sections of the anterior & posterior digestive tract Enzyme analysis –Determine the enzymatic activity of pepsin, trypsin, chymotrypsin, lipase & amylase from sections of the digestive tract Plasma –Cholesterol –Triacylglycerides Fusion of intestinal villi. Villi are somewhat shortened adjacent to the fused ones. Rainbow trout, (Oncorhynchus mykiss) digestive tract Normal villi of large intestine, longitudinal section of outer muscular layer, a thin pink-staining stratum compactum & villi. Villi are long, have space between them. Apical vacuoles seen in mucosal epithelium.

Outcomes Directly benefit YTK industry in Australia –By providing information to develop sustainable, cost effective dietary formulations, i.e. Identification of optimum P:E ratios Replacement of fish meal & fish oil with more sustainable plant & terrestrial sources to reduce ingredient costs Leading to enhanced sustainable productivity of YTK cultured at sub-optimal water temperatures

Acknowledgements Australian Seafood CRC Clean Seas Tuna Ltd. –Mr. Mike Thomson –Mr. Chester Wilkes Flinders University –Dr. Kathy Schuller SARDI-Aquatic Sciences –Dr Valeria Torok Department of Primary Industries Port Stephens –Dr. Mark Booth University of Tasmania –Dr. Louise Ward “ This work formed part of a project of the Australian Seafood Cooperative Research Centre, and received funds from the Australian Government’s CRCs Programme, the Fisheries R&D Corporation and other CRC Participants”.