Aquaculture of the Bluefin Tuna
Taxonomy
Genus Thunnus
Species: Maccoyii, Orientalis, Thynnus
Economic importance, market
price, market locations, country
 The Atlantic bluefin is a
highly sought-after
delicacy for sushi in Asia
 A single fish has sold for
around 1.8 million
dollars
 The largest driver of
demand for bluefin tuna
is the market in Japan.
Life cycle and larval stages
 Scientists in Japan achieved
completion of the life cycle
under controlled conditions
after 32 years.
 Not achieved on commercialscale, capture based
aquaculture has developed
significantly.
 The larvae are ~3mm when
they hatch and grow at a rate
of 1mm per day after that.
 Female bluefins reach sexual
maturity at about 5 years old.
Reproduction in captivity
 Spawning occurs from April to June in the Gulf of
Mexico and from May/June to August in the
Mediterranean.
 Sexual maturity of Atlantic bluefin tuna is reached at
the age of 5-8 years, while Eastern Atlantic maturity is
reached at 4-5 years.
 Bluefin tunas may release from 5 to 30 million eggs
 Spawning occurs in open water close to the surface
and in areas where survival expectations are highest.
Production Methods
 Bluefin tuna farming based on stocking of wild-caught individuals
 Purse seine is the most effective capture system
 Wild tunas are caught at different life-cycle stages
 Fish finders and sonar are used to detect Bluefin tuna schools
 They are kept alive and transferred to towing cages usually by sewing the nets
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together, difficult and inefficient
Tugboats used to transfer tuna in the towing cages to farm site. Low
transportation speed critical, cause for long trips
In Mediterranean, the companies start stocking their tuna cages in May/June
Mediterranean tuna farms use circular ring type open-sea floating net cages.
Size of cages vary from 30-90m in diameter, with net depths ranging from 1530m
Farming cages designed to contain smaller tuna specimens for long periods of
time. Fattening season is linked to market demand/opportunity
Quotas put in place by ICCAT (International Commission for the Conservation of
the Atlantic Tuna) to limit the number of tuna harvested
Feeds and Feeding
 Bluefin tuna are fed with a mixed diet composed of a variety of small
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pelagic species
Proportion and volume of feed varies among the farms of different
countries
The Mediterranean countries engaged in the tuna farming obtain bait fish
from locally fished stocks
Fed 1-3 times a day with a mixture of defrosted bait fish
When the tuna are not fed at own pleasure, daily input varies from 2-10%
of the estimated tuna biomass
Difficult to record initial weight or length measurements without losing the
tuna in the handling process, little information about food intake so
overfeeding is a common practice.
Feed conversion ratios are 15-20:1 for large specimens and 10-15:1 for
smaller fish
They maintain a high body temperature and their constant movement
implies a high energy demand, resulting in 5% of total energy input is used
for body growth
Water chemistry and
environmental requirements in
culture
 Spawning has only been recorded where
the waters are 25-30C
Advantages and
disadvantages of the species
Disadvantages:
Advantages:
 Long life before they can be
 High demand
harvested
 A closed life-cycle has not
yet been achieved for
practical use
 There is not yet an effective
feeding practice
 High market price
 They are becoming extinct,
so aquaculture is beneficial
 Mediterranean area benefits
by making huge financial
investments that have
allowed the modernization
of equipment