Thunnus maccoyii (Castelnau, 1872)

Bluefin

Species recognized by FishBase external link, R Froese & D Pauly (eds) in 
IUCN Red List Status: Critically Endangered (CR) external link Showing: scientific names

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Thunnus maccoyii (Castelnau, 1872)

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Thunnus maccoyii (Castelnau, 1872)
Thunnus maccoyii (Castelnau, 1872)

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Overview

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Mark Westneat
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The bluefin tunas are among the largest and fastest open ocean fishes and are important economically and culturally in many parts of the world. There are three species of bluefin tuna- the prized and endangered Atlantic bluefin (Thunnus thynnus), the widespread but similarly overfished Pacific bluefin (Thunnus orientalis), and the smaller but also tasty Southern bluefin tuna (Thunnus mccoyi). Bluefin tunas are spectacular swimming machines with torpedo-shaped, streamlined bodies built for speed and high-powered muscle and tendon systems that have evolved for high endurance. Bluefin tunas are warm-blooded, a rare trait among fish, and are thus able to adjust their body temperature, keeping their body temperatures higher than the surrounding water, which is why they are so well adapted to cooler ocean waters. Bluefin tunas are considered exceptionally good to eat, particularly by those who enjoy various forms of raw fish such as sushi and sashimi, and all species of bluefin tuna are pursued constantly by the fishing industry and by sport fishermen. As a result, overfishing throughout their range has driven their numbers to critically low levels. Some populations of bluefin tuna are thought be extinct and others are critically endangered.

Biology

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Bluefin tuna spend their lives swimming constantly through the oceans cruising at 2 - 3km per hour (4), although they are able to reach speeds of 70 km per hour (5). Individuals swim together in shoals and these migrate vast distances from spawning grounds in the Indian Ocean to feeding grounds in colder southern waters (3). It is thought that females do not spawn until they reach around 1.5 metres in length, which corresponds to at least 8 years of age (4). A mature female will produce several million eggs in one spawning period (4). The breeding season runs from September and October until March (3), and occurs in Indonesian waters (4). Juveniles are then known to group together during the summer months in coastal waters off the southern coast of Australia until they reach around 5 years old, after which they are more consistently associated with deeper waters (4). These oceanic fish are opportunistic feeders, preying on a wide variety of other fish as well as crustaceans, cephalopods (such as squid and octopus) and other marine animals (6). Bluefin tuna are thought to be long-lived with a life expectancy possibly as long as 40 years (5).
Mark Westneat. Curator. "Thunnus maccoyii (Castelnau, 1872)". Encyclopedia of Life, available from "http://www.eol.org/pages/212861". Accessed 20 Mar 2010.