1. OCEAN FISH DYNAMICS
Class OSTEICHTHYES (PISCES)
Subclass ACTINOPTERYGII
Superorder TELEOSTEA
Order PERCIFORMES
Family TUNNIDAE
Thunnus thynnus
Also > 400 cm length
> 650 Kg weight
Eyes, mouth, and head, large and evident

2. Two different populations in the North Atlantic
BFTW reproduction area, the Gulf of Mexico
BFTE reproduction area, the mediterranean Sea
The tuna fishery in the Mediterranean exists from 6,000 y BC

3. In both Mediterranean and Gulf of Mexico, tuna came back from all the Atlantic to already known reproduction areas
For feeding tuna go wherever they find biomass to eat. (generally water front areas)

4. After fertilization of eggs, juveniles reach 1 cm in 10 days
They are not able to move over geographical areas
They have been found in all the regions of the Mediterranean but Alboran, Lion, Ligurian, N Adriatic, N Aegean

5. From 200 years juveniles of < 1000 g are collected in any part of the Mediterranean in the period July-October
Larvae are initially lecitotrophic
They became planktotrophic after 3 days
They feed on copepods
Large mouth and eyes,
they are predators also by juveniles
Adults prey mainly on anchovies; they reach 300 Kg at the age of 15 y

6. The adulthood is reached at an age of 8-9 (Atlantic population) or at 3-4 (Mediterranean population)
Adults are commonly found out from their reproductive areas, and down to m C

7. Tuna avoid
river deriving water
Support 3 < T < 30°C
They eat about 10% of their bodyweight every day
A relatively large heart
Large amounts of Mioglobine
Capillary net
Vascular system and bodymass good to maintain the body temperature up to 10°C over the external environment

8. Tuna have not a good (large) gas bladder
The swim is based on
Discontinuous accelerations
Hydrodynamic bodysize
Gregarious behaviour

9. Atlantic bluefin tuna belong to two separate populations
Different age of adulthood
Different spawning areas
Different migrating behaviour
Those in the western Mediterranean migrate also in the East Atlantic
Those in the central Mediterranean migrate only inside the Mediterranean

10. FISHERY
Fenicians: mobile nets (1000 BC – 700 AD)
Nowadays
Flying nets
Palancari
Sport fishing
Bizantines: fixed nets (700 AD)
Hohenstaufen: tonnare in Sicily (1200 AD)