Sustainable fisheries and aquaculture – Tuna (Thunnus thynnus)

 
 
 
 

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Scombridae
Genus: Thunnus
Species: Thunnus thynnus

 
Synonyms

 
There are several different names for the common tuna fish:-

 
Thynnus thynnus Cuvier, 1817
Thynnus mediterraneus Risso, 1826
Thynnus vulgaris Cuvier in Cuvier & Valencienes, 1831
Thynnus orientalis Temminck & Schlegel, 1844
Thunnus vulgaris South, 1845
Thynnus secundo-dorsalis Storer, 1855
Orcynus thynnus Poey, 1875
Orcynus schlegelii Steindachner in Steindachner & Döderlein, 1884
Albacora thynnus Jordan, 1888
Thunnus thynnus Jordan & Evermann, 1896
Thunnus schlegelii Jordan & Snyder, 1900
Thunnus secundodorsalis Jordan & Evermann, 1926
Thunnus thynnus thynnus Serventy, 1956

 
Features

 
Atlantic Bluefin tuna, Thunnus thynnus (Linnaeus, 1758), aka Bluefin tuna, Horse mackerel, Northern Bluefin tuna is regarded as one of the most highly evolved fish species and one of the most prized fish in danger of overfishing. (FAO: Species)

FileTuna-lifecycle1

 
Tuna, originating from the Greek word meaning “to rush,” usually swim at speeds of 54 kilometers per hour (more than 33 miles per hour), can maintain 8 kts for some time, and can rarely break 20 kts for short periods. (marinebio) Tunas must swim constantly or they will sink. These are some of the most magnificent creatures in the sea. Because of this level of activity, they require a large amount of energy and a good oxygen supply which they get by swimming fast, moving large volumes of water past their gulls. Tunas quickly accelerate when sensing food, reaching their top speed within one second. (Karleskint 1998)

 
The Atlantic Bluefin tuna is the largest member of the Scombridae Family (albacores, bonitos, mackerels, tunas), its deepest part being near the middle of its first dorsal fin base. It has 34 to 43 gillrakers on its first arch. The second dorsal fin is higher than first and the pectoral fins are very short. It is one of the largest bony fishes with 18 vertebrae precaudal plus 21 caudal and can reach lengths of up to 3 m, although they are more commonly found from 0.5-2 m in length. (marinebio)

 
Adult weights range from 136-680 kg, although the upper weight range is rare. They can dive as deep as 914 m, and are known to swim long distances as they are a highly migratory species. The average lifespan of Bluefin tuna is 15-30 years. (marinebio)

 
Atlantic Bluefins are dark blue to black near the dorsal surface and silvery white down its lower sides, near the ventral surface with colourless transverse lines alternated with rows of colourless dots (the latter dominate in older fish), which is visible only in fresh specimens. The first dorsal fin is yellow or bluish and the second is a reddish-brown. The anal fin and finlets are dusky yellow, edged with black. The median caudal keel is black in adults. (FAO: Species)

 
Atlantic Bluefin are homeothermic (“warm-blooded”) and are therefore able to thermoregulate keeping their body temperatures higher than the surrounding water, which is why they are so well adapted to colder waters. (FAO: Species & marinebio) The higher temperature also allows the fish to metabolize faster. Nerve impulses travel more quickly, digestion is more rapid and the large skeletal muscles used for swimming contract and relax about three times as fast as any other fish which helps account for the tuna’s great strength and speed. (Karleskint 1998)

 
For more detail on this paper, click here to download the pdf file.

 
 


Leave a Reply

Your email address will not be published. Required fields are marked *


PHP Code Snippets Powered By : XYZScripts.com