The more they have learned about tuna, the greater the mysteries surrounding these remarkable fish. Some of the unresolved questions are: how do the tuna navigate over thousands of miles in the trackless wilderness of the open ocean?
Why do female tuna lay such enormous quantities of eggs? On the average, only two of the millions of eggs laid by a female can survive to adulthood. Are the remaining eggs and larvae basically an evolutionary device to provide food, directly or indirectly, which will allow a few young individuals to survive and grow?
How do adult tuna, living at times in the desert waters of the high seas, obtain the quantities of food they need to swim continuously, let alone to reach very large sizes, and to produce large quantities of reproductive products? But the greatest mystery of the tuna is the mystery of life itself. Are the tuna no more than marvelously efficient swimming, feeding and breeding machines?
The tuna possesses a streamlined body to reduce water resistance and conserve energy for trans-Pacific migrations. Retractable fins also allow a freer flow of water when navigational changes do not require their use.
Imagine what it's like for a tiny insect to jump and fly as quickly as they do. This method increases the likelihood that the eggs will be fertilized and decreases the chances that they will be eaten by egg predators. There are at least two known populations of Atlantic bluefin tuna, one that reproduces in the Gulf of Mexico and one that reproduces in the Mediterranean Sea.
Some researchers believe that the Mediterranean population actually represents two populations one in the west and one in the east plus the Black Sea. This further division has some implications for fisheries management, because the fish in the eastern Mediterranean are generally considered more of a conservation concern than those in the western Mediterranean.
Though almost all fishes are cold blooded, Atlantic Bluefin have a specialized blood vessel structure — called a countercurrent exchanger — that allows them to maintain a body temperature that is higher than the surrounding water. This adaptation provides them with a major advantage when hunting in cold water, by allowing them to move more quickly and intelligently.
The Atlantic bluefin tuna is one of the fastest swimmers in the ocean. Like some shark species, Atlantic Bluefin must constantly swim. In order to obtain oxygen from the water, fishes pass water over their gills.
The tunas lack the ability to do so while stopped, so they must continuously swim forward with their mouths open to keep their blood oxygenated. The Atlantic bluefin tuna is a highly prized food fish and is fished heavily throughout its range. They can swim up to 18 mph for short periods of time. They are the largest of the tuna species, reaching upwards of kg and 3 meters in length. There are three species in each of the Pacific, Atlantic and Southern Oceans.
In all oceans bluefins are known for their impressive migrations, routinely crossing ocean basins. Unique Characteristic: Like all tunas, bluefin are endothermic and can regionally elevate body temperature above ambient water temperature. Comparing results from bluefin with yellowfin and albacore tuna will provide important insights into how endothermy influences movements and habitat selection.
The video below features an interview with scientist Barbara Block where she explains more about the unique adaptations of the Bluefin tuna. In the following video, watch to see how the tuna are caught and how the tags are implanted into the fish. Skip to main content. You are here Home » The Library.
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