TUNA FARMINGTUNA FARMING

Ivana MiletićIvana MiletićMinistry of Agriculture and Ministry of Agriculture and

Forestry Forestry Directorate of Fisheries Directorate of Fisheries

Zagreb, CroatiaZagreb, Croatia

TUNA TUNA FARMINGFARMING

Ivana MiletićIvana MiletićMinistry of AgricultureMinistry of Agriculture

FisheriesFisheries and and Rural Rural DevelopmentDevelopment

Directorate of Fisheries Directorate of Fisheries Zagreb, CroatiaZagreb, Croatia

Thunnus thynnusThunnus thynnusBluefin tunaBluefin tuna

It wide spreadIt wide spread in thein the Mediterranean SeaMediterranean Sea and and thethe Atlantic from 60˚N- 40˚SAtlantic from 60˚N- 40˚S

Year Year Quota Quota (Tons)(Tons)2000 2000 8768762001 8762001 8762002 12322002 12322003 11552003 11552004 9352004 9352005 1069 2005 1069 2006 10172006 10172007 862,312007 862,312008 833,082008 833,082009 6402009 6402010 393,502010 393,502011 376,012011 376,01

Tuna quota for CroatiaTuna quota for Croatia

Tuna production for Tuna production for CroatiaCroatia

YearYear TonsTons2000 11672000 11672001 30452001 30452002 39712002 39712003 46792003 4679

2004 37772004 3777 2005 34252005 3425 2006 67002006 6700 2007 41802007 4180 2008 37112008 3711 2009 42002009 4200 2010 no data yet2010 no data yet

Tuna fishing boatTuna fishing boat

Towing boatsTowing boats

MaximumMaximum speed ofspeed of towing is 1.5 knotstowing is 1.5 knots Daily control of fish conditionsDaily control of fish conditions by diversby divers Daily removing mortality by diversDaily removing mortality by divers

Tuna fTuna farmarm

TTunauna is kept in in circular cage, 50 - 60 m is kept in in circular cage, 50 - 60 m in in diameterdiameter TThe net vary in size (19+1m, 25+1m, 30+1mhe net vary in size (19+1m, 25+1m, 30+1m)) EEye ye wwidthidth vary from 55-85 cm vary from 55-85 cm

Fishing and farming Fishing and farming tetecchniquehnique is totally improved is totally improved what gives the base for perennial cycle and what gives the base for perennial cycle and multiplication of original body massmultiplication of original body mass

Towing boat brings cage to prepared feeding cagesTowing boat brings cage to prepared feeding cages

The door of towing cageThe door of towing cage is linked with the door of is linked with the door of feeding cagefeeding cage

In order to manipulated the net is In order to manipulated the net is easeasiilyly

Transfer of fish is done by lifting the net on the oTransfer of fish is done by lifting the net on the opppositeposite side side of the door of towed cageof the door of towed cage

What reduces the space in towed cage and forces the fisWhat reduces the space in towed cage and forces the fis feeding cagesfeeding cages

The door of cage is closed and fish is rady to be fedThe door of cage is closed and fish is rady to be fed

The door of towing cageThe door of towing cage is linked with the is linked with the door of door of feeding cagefeeding cage

In order to manipulated the net is In order to manipulated the net is easeasiilyly

Transfer of fish is done by lifting the net on Transfer of fish is done by lifting the net on the the oopppositeposite side side of the door of towed cageof the door of towed cage

What reduces the space in towed cage and What reduces the space in towed cage and forces forces the fish inthe fish in feeding cagesfeeding cages

The door of cage is closed and fish is The door of cage is closed and fish is readilyreadily to be to be fedfed

Tuna cagesTuna cages

Purse seining fishPurse seining fish

PilchardPilchard AnchhovyAnchhovy SpratSprat MackerelMackerel Spanish mackerelSpanish mackerel

Frozen foodFrozen food

herringsherrings

TunaTuna feedingfeeding

TTunauna is feed domes is feed domesttiicc purse seining fish purse seining fish Import frozen hImport frozen heerrings orrrings or sardinsardinee Quantity of food dependQuantity of food dependss of two parameters of two parameters:: * * fat content in foodfat content in food * * temperature of seatemperature of sea

The higher the temperature the more food is needed due to The higher the temperature the more food is needed due to faster metabolism and other processes at higher temperaturefaster metabolism and other processes at higher temperature The fatter the food is the less food is neededThe fatter the food is the less food is neededDaily quantity of food is 2 to 7 % of tuna body mass.Daily quantity of food is 2 to 7 % of tuna body mass.

Static platform for feeding Static platform for feeding tunatuna

Feeding process is manual, bFeeding process is manual, byy shovel paddle shovel paddle

Workers throw the food in high archWorkers throw the food in high arch

Every cages is served 3 to 4 times per dayEvery cages is served 3 to 4 times per day

Tuna eats 50% of daily planned amount of food in the Tuna eats 50% of daily planned amount of food in the first feedingfirst feeding In any further feeding tuna eats less food than in In any further feeding tuna eats less food than in previous feedingsprevious feedings Small fish is fed from the platform cause they behaviorSmall fish is fed from the platform cause they behavior differently than the fish that weight 15 kg or moredifferently than the fish that weight 15 kg or more

Tuna eats 50% of daily planned amount of food Tuna eats 50% of daily planned amount of food in in the first feedingthe first feeding In any further feeding tuna eats less food than In any further feeding tuna eats less food than in in previous feedingsprevious feedings Small fish is fed from the platform cause they Small fish is fed from the platform cause they behaviorbehavior differently than the fish that weight differently than the fish that weight 15 kg 15 kg or moreor more

Smaller fish is more predatory, swims faster and has noSmaller fish is more predatory, swims faster and has no strict swimming direction than larger fishstrict swimming direction than larger fish During the feeding the fish makes lot of fuss and due toDuring the feeding the fish makes lot of fuss and due to their natural predatortheir natural predator instinct, fish entanglement into instinct, fish entanglement into the netthe net or mutually hurtingor mutually hurting

The feeding from the boat is done in the same way as The feeding from the boat is done in the same way as from the platformfrom the platform The difference is that at the boat food is stored in plasticThe difference is that at the boat food is stored in plastic boxes in which the fish is defrosted at the same time if boxes in which the fish is defrosted at the same time if it comes from the importit comes from the import

The feeding from the boat is done in the The feeding from the boat is done in the same way same way as from the platformas from the platform The difference is that at the boat food is The difference is that at the boat food is stored in stored in plasticplastic boxes in which the fish is defrosted boxes in which the fish is defrosted at the at the same time if it comes from the importsame time if it comes from the import

The fat content in the meat of fish used for tuna feedingThe fat content in the meat of fish used for tuna feeding::

Anchovy Anchovy - - 0.7 – 14.5 %0.7 – 14.5 % Pilchard Pilchard - - 0.9 – 17.2 %0.9 – 17.2 % Spanish mackerel Spanish mackerel - - 1.1 – 19.4 %1.1 – 19.4 % Mackerel Mackerel - - 1.0 – 20.0 %1.0 – 20.0 % Herring Herring - - 0.4 – 29.7 %0.4 – 29.7 %

Biomass and quantity of used food per cageBiomass and quantity of used food per cage

* growth of the smallest fish is * growth of the smallest fish is the highestthe highest

**The quantity of used food decreases by fall of the The quantity of used food decreases by fall of the temperaturestemperatures

**During the winter period fish metabolism is slow and demand for the During the winter period fish metabolism is slow and demand for the food is poorfood is poor

CagesCages no 1,2,3,4 no 1,2,3,4

Tuna Tuna measuring by fixed metermeasuring by fixed meter

Tuna growth can be monitor by used food Tuna growth can be monitor by used food and daily and daily biometrybiometry TheThe measuring was done by fixed meter and measuring was done by fixed meter and technicaltechnical skale skale

1. LT – 1. LT – total lengthtotal length 2. LC – 2. LC – head lengthhead length 3. PA – 3. PA – torso lengthtorso length to anal to anal 4. LCA – 4. LCA – caudal fin caudal fin lengthlength

5. O – 5. O – eye diametereye diameter 6. LP – 6. LP – pectoral fin lengthpectoral fin length 7. LD – 7. LD – dorsal fin lengthdorsal fin length 8. NN – 8. NN – caudal fin caudal fin widthwidth

9. LTR – 9. LTR – torso lengthtorso length

Relation of mass and the length of tuna bodyRelation of mass and the length of tuna body

* Tuna * Tuna does not eat in nature as often does not eat in nature as often in captivityin captivity

fed fed tunatuna

unfedunfed tuna tuna

HarvestingHarvesting

In feeding cages the fish is first closed by use In feeding cages the fish is first closed by use of of smaller encircling netssmaller encircling nets

Divers are going downDivers are going down Stun the individual specimens of fish Stun the individual specimens of fish by probing its frontal boneby probing its frontal bone

The fish is hooked and lifted on board of vesselThe fish is hooked and lifted on board of vessel

Cutting of lateral veins immediately behind the breastCutting of lateral veins immediately behind the breast fins for bleeding purposesfins for bleeding purposes After that the spinal chord is destroyedAfter that the spinal chord is destroyed

Wire was needle through backbone to abort all nervesWire was needle through backbone to abort all nerves

Evisceration is carried outEvisceration is carried out as well as removingas well as removing of gills of gills and guttingand gutting

Tuna Tuna weight weight

Tuna placed into plastic boxes for chillingTuna placed into plastic boxes for chilling

Whole operation is not lasting longer than few minutesWhole operation is not lasting longer than few minutes

Tuna transport to Japanese boat Tuna transport to Japanese boat for finalefor finale processing and freezingprocessing and freezing

Tuna Tuna scalescale

Tuna countingTuna counting

FinFinss cutting cutting

Cutting operculumCutting operculum

FinaleFinale cleaningcleaning

Finale visual control of qualityFinale visual control of quality

Sample of tailSample of tail is used for color analysisis used for color analysis The colors is related to the fat content of the meat The colors is related to the fat content of the meat and therefore with the qualityand therefore with the quality

393 kg393 kg