Comparing performance of Atlantic salmon in sea cages and different tank sizes

Transcription

1 AQUAculture infrastructures for EXCELLence in European Fish research Comparing performance of Atlantic salmon in sea cages and different tank sizes Åsa M Espmark 1, Jelena Kolarevic 1, Torbjørn Åsgård 1, Finn V Willumsen 2, Guttorm Lange 2, Jo A Alfredsen 3, Morten Alver 3, Gunnar Senneset 4, Jens Birkevold 4, Bendik Fyhn Terjesen 1 1 Nofima AS, Sunndalsøra, Norway 2 Aquaculture Engineering (ACE), c/o SINTEF Fisheries and Aquaculture, Trondheim, Norway; 3 Department of Engineering Cybernetics, Norwegian University of Science and Technology, Trondheim, Norway 4 Sintef Fisheries and Aquaculture, Trondheim, Norway.

2 Background Many bottlenecks in aquaculture industry are dealt with in controlled small scale experiment A tight collaboration between industry and research units have been very important for the success that fish farming has become and is of high significance for further growth The research designs in small scale has to be representative for the large scale industry

3 Objectives The aim of this experiment was to compare effects of rearing tank scale, and different scaling histories with commercially sized sea cages on Atlantic salmon performance. Experiment was run in Nofima Centre for Recirculation in Aquaculture (NCRA), in SW flow-through system and in sea cages (3x120m), Salmar sea farm at Korsneset The experiment at NCRA was presented at EAS in Trondheim 2013, and will therefore not be presented in detail now. Here we focus on the comparison between tanks and cages

4 Material and Methods Overall schedule Phase I: March 2012: Same batch of salmon smolt were transported by truck 400 km to Nofima Centre for Recirculation in Aquaculture (NCRA), Sunndalsøra (N=13 000; 72.1±2.8g) and by well-boat 313 km to 120m sea cages at Salmar sea farm at Korsneset (N= ; 72.1±2.8g) Phase II Tanks: March - May 2012: Creating scaling history. Salmon smolt acclimatized in 11m, 1m or 2m tanks Phase III Tanks: May October 2012: Grow out period. In May fish were redistributed from phase II tanks to 1m, 2m, or 7m tanks October 2012: Ending experiment in tanks and cages

5 Experimental design Espmark et al, Unpublished Phase I

6 Variables that were standardized - tanks Material and Methods Variables that were not standardized but measured/monitored - tanks Variables that were standardized between cage and tank Initial fish density Feed distribution Fish genetic & batch origin Feed type Water velocity Feeding time regime adjusted in tanks Light ( lux) Tank water turnover Feed pellets same producer and lot Temperature Water quality parameters (except O 2 ) Temperature adjusted in tanks, according to cage Oxygen saturation Light duration Tank geometry Espmark et al, Unpublished

7 Material and Methods - temperature Espmark et al, Unpublished

8 Espmark et al, Unpublished Material and Methods water velocity tanks Direction of the water flow Tank inlet % of total tank width < Top view 9% 35% 63% % of total tank depth Water velocity (cm/s) m 2 m May June August Measured at 9 standardized points within tanks using a Höntzsch propeller Lateral tank with HLOG software view Final velocities shown in the graph Planned increase in water flow represent average velocity measured at 9 points for each tank scale

9 Material and Methods water quality tanks Regularly measurements of: Salinity (ppt) ph Turbidity (NTU) CO 2 (mg/l) TAN (mg/l) Alkalinity (mg/l)

10 Material and Methods water quality sea cages Oxygen 3m, 7m and 10m Temp 3m, 5m, 7m, 10m Salinity 5m Current speed and direction 5m

11 Results Accumulated mortality Tanks Cages Espmark et al, Unpublished Included mortality due to handling and transfer Included an outbreak of pancreas disease; however, this is frequently observed in commercial farming

12 Results individual weight Espmark et al, Unpublished Tanks Cages Growth (g/ind) Mar-12 Apr-12 May-12 Jun-12 Jul-12 Aug-12 Sep-12 Oct-12 11m 7m 2m 2m 1m 2m 11m 2m 11m 1m

13 Espmark et al, Unpublished Results growth (Specific growth rate SGR and Thermal growth coefficient TGC) SGR = ((ln W 2 ln W 1 )*100)/days

14 Results Coefficient of variation (CV) between units (n=3, each treatment) CV (%) The practical results of a lower variance between statistical units: it will improve detectability of smaller differences using the same number of replicates or fewer replicates are needed to detect the same treatment difference

15 Espmark et al, Unpublished Results Mass specific feed intake (% BW/day) Tanks Cages The average for the whole experiment is approx the same for tanks and cages, but increase with time in tanks while cages fluctuate

16 Espmark et al, Unpublished Results Somatic index

17 Discussion This long term experiment demonstrates that growing fish in different unit sizes result in different fish performance The best growth was obtained in the 7m tanks, while the worst scenario was to move the fish from large 11m tanks to small 1m tanks Growth rate in the sea cages was equal to the 2m tanks. However largest CSI in cages suggest fit fish These findings suggest that there is potential for improved growth rate in sea cages

18 Discussion Mortality in sea cages comparable to the 7m tanks. Highest mortality recorded in 1m tanks Tanks: transfer matters, high mortality when moved from large to smaller tanks. Handling is challenging for the fish Cages: mortality of approximately 8-9% includes an outbreak of pancreas disease; however, this is a normal occurrence and may also happen during experiments in cages

19 Discussion For research questions the results demonstrates the importance of representative sampling It is crucial that handling of experimental fish is kept at a minimum and is done with care Cause high mortality Delay acclimation time Sufficient acclimation time for optimal research is unknown Low CV in 7m tanks compared to sea cages: will improve detectability of smaller differences using the same number of replicates fewer replicates are needed to detect the same treatment difference These questions, amongst others are topics for AquaExcel2020 EU application that was submitted in September

20 Would you like to find out more? AQUAEXCEL INDUSTRY WORKSHOP: Research Infrastructures: adding value to European aquaculture industry Friday, 17 th October Kicking off at 10.30am Room 11 (Exhibition Area) See you there!

21 This work has been partly funded under the EU seventh Framework Program by the AQUAEXCEL project N : AQUAculture infrastructures for EXCELLence in European Fish Research Thank you for your attention asa.espmark@nofima.no Website: Tel: Special thanks to: Technicians at Nofima Salmar Settefisk AS (Follasmolt) Salmar Farming (Korsneset sea farm)

22 DISCLAIMER The research leading to these results has received funding from the European Union s Seventh Framework Programme (FP7/ ) under grant agreement no This publication reflects the views only of the author, and the European Union cannot be held responsible for any use which may be made of the information contained therein.