Fish welfare and behavioural needs as design requirements for developing sustainable aquaculture constructions

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1 Fish and Ships 22. March 2012 Towards sustainable offshore aquaculture operations by bridging marine and maritime research and knowledge: Fish welfare and behavioural needs as design requirements for developing sustainable aquaculture constructions Østen Jensen & Arne Fredheim

2 Content Introduction The Norwegian fish farming industry Integrating technological and biological research issues Submergible cage farming Bio-fouling Preventing Escapes Design of sustainable aquaculture technology

3 Salmon farming the most efficient food production in the world? Production at the best sites: tonnes per year tonnes per man-year

4 Introduction The number challenges Increasingly larger farms Circumference m More than fish in one single cage cages at one site More than tons at one location 300 million salmon in Norwegian cages One tenth of a percentage is several hundred thousand fish wild salmon return each year to spawn Ill: Aqualine

5 Introduction The environmental challenge Farming the deep blue conference (2004) Class 1 to 4 1. Sheltered inshore 2. Semi exposed inshore 3. Expose offshore 4. Open ocean offshore Exposure Current Wave height and length Duration of weather High energy sites! Farming the deep blue (2004)

6 CREATE Centre for research based innovation

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8 Submergible cage farming The biological criteria for submerged production Challenge - the physiological and behavioural limitations for production open swim bladder (physostomous): e.g. salmon closed swim bladder (physoclisti): e.g. cod, sea bream, Results - management protocols Submerge/elevation speed Submerge periods/lengths Develop technological solutions to reflect the biological needs

9 Submergible farming Submergence of physostomous fish - SubSalmon Cage Environment Laboratory, IMR, Matre ~1200 m 3 cages (12 x 12 x 14 m) AIM: Determine effects of submergence on behaviour and growth of salmon Experiment 1 Approx 4000 salmon of 0.5 kg per cage 22 days of submergence Continuous artificial lighting (May) Experiment 2 Approx 2500 salmon of 4.5 kg per cage 42 days of submergence Natural light (long dark nights in Dec/Jan)

10 Submergible farming SubSalmon Summary and conclusion 22 days submergence swim bladder empty Increased swimming speed Regained normal behaviour after re-surfacing No mortality 42 days at 10 m without artificial light : Increased tilted swimming Negative effects on snout wear and vertebrae Depressed feed intake, growth and feed utilization Tolerate shallow submergence for days to weeks without major changes to important production parameters given continuous light and sufficient space Not acceptable to submerge salmon long, deep and dark Future solutions/ideas: Re-surfacing at periodic intervals to re-fill swim bladders Artificial lights to reduce tilted swimming Providing an underwater air pocket to enable swim bladders re-fill

11 Submergible farming Atlantic salmon (Salmo salar) refill the swimbladder from an air-filled dome in a fully submerged cage Airfilled dome in a submersible cage is previously tested, but behaviour before, during and after is not described How and how often do salmon refill the swimbladder? Are there any risk (barotrauma) shortly after re-surfacing?

12 Submergible farming Conclusions (prelim.) Approx. 95% of the salmon utilized the air-filled dome during submergence (most probably 100%, some technical problems with the tracking system) The refilling frequency was in average times per day per fish Normal behaviour was observed after the re-surfacing -> hence no risk?

13 ReduceDelice Can salmon refilling behaviour be used to delouse salmon A typical refilling cycle quick burst of swimming towards the air pocket (A), fish breaking the water by lifting the upper jaw above the surface (B), rapid swimming in a downward direction (C).

14 Biofouling Hydroids Fish farmers need clean nets: To reduce additional weight and ensure the stability of cages To ensure sufficient water exchange across the nets and maintain good water quality in cages To ensure cleaner wrasse predominantly feed on salmon lice Underwater washing make the biofouling community more homogeneous Rapid re-growth and re-colonization (14 days) Understand the connections between hydroids, environmental conditions and farming operations and technology Design new cleaning strategies

15 Bio-fouling Hydroids understand the biology Ectopleura larynx dominates fouling communities on aquaculture nets in SW to Mid Norway between July and November. The aims of this study were: To determine the effects of heat and acetic acid treatments on the settlement of larvae the survival of juvenile and adult Ectopleura larynx To contribute to the development of novel cleaning methods

16 Survival (%) Survival (%) Bio-fouling Conclusions Short term immersions in heated seawater or acetic acid solutions could prevent settlement and lead to mortality of hydroids Heat 50 ⁰C effective against larvae and juveniles 60 ⁰C effective against adults Acetic acid 0.2 % for 1 min effective against larvae and juveniles 2 % effective against larvae, juveniles and adults. Novel cleaning methods may utilise these results to effectively kill hydroids on nets Acetic acid- Adults Heat - Adults Control Concentration (%) Control Temperature (⁰C) Control 1 s 3 s 10 s 1 min 5 min

17 Why do fish escape Examples of biological causes Fish biting Cod, Sea Bream (and other fish) bite and nibble on netting and create holes Difference in exploratory behavior species to find and swim through holes Understanding of fish behavior to design proper net cage

18 Loads from fish bite Lateral pull force varied from N times stronger during lengthy biting compared to brief bites. Cod 610 g => pull force 1.5sx weight. Cod 180 g => pull force 2x weight. Pull forces exceeded break force of single nylon filaments

19 Simulation of fish bite to evaluate resitance of net materials Equipment to simulate cod bite were developed. Based on the size and geometry of cod teeth Different multifilament net materials were tested. Loosely knitted material had poor resistance compared to tightly knitted material. Improved filament strength led to improved biting resistance Coating of the material improved the resistance

20 Design of sustainable aquaculture technology The simple but complex structure More complex to analyze than rigid ships and offshore construction More fragile strength, wear and tear Less than 5% of the total costs

21 Our idea: To meet future challenges - multi-disciplinary research needed Complicated industry Living animals At sea, off coast and moving Biology, veterinary science, engineering, ITC Design cycle - Multi-disciplinary approach 1. Understand fish behavior and needs 2. Develop operational procedures and management protocols 3. Technological solutions to support biological and operational needs Based on conditions Environmental sustainable Fish welfare Financial viability

22 Thank you for your attention