by Barney
There are many species of Tuna. At Save-On Foods in Fort Nelson almost all the canned tuna is Albacore and SkipJack.
We wanted to learn about the physiology of tuna and I focused on yellow fin tuna.
| Appearance | Weight /Length |
|---|---|
| torpedo-shaped with dark metallic blue backs, yellow sides, and a silver belly. | weights of at least 400 pounds |
| have very long anal and dorsal fins and finlets that are bright yellow. | lengths of nearly 2 meters |
Tuna are different then other fish for many reasons. The biggest difference , due to the physiology of their respiratory system, tunas are obligate ram ventilators. This means they need to swim all most all the time to make water pass through their gills. Because they swim constantly to get blood into their blood, their muscular metabolism continuously generates heat, which gives them a cool feature among all bony fishes. Yellowfin Tuns have the ability to regulate their body temperatures. That means that tuna are “warm blooded”. This feature allows them to tolerate a wide range of water temperatures. It also allows them to swim really fast. This helps them catch their prey.
Tuna can Regulate their body temperature.
| Comparison of Tuna and sharks | COMPARISON OF TUNA AND SHARKS Cross-section |
|---|---|
 |   |
| Tuna have a warmer core then sharks and other fish. | You can see that the red muscle in a warm blooded fish is found near the core where it is warmer. This feature allows Tuna swim long distances. |
Below are the seven species of tuna that are most often fished commercially:
| Skipjack | Albacore |
|---|---|
 |  |
| Skipjack are the smallest of the commercial tuna species. They are found mainly in the tropical areas of the Atlantic, Indian and Pacific Oceans, skipjack are the main species associated with FADs. Skipjack tuna is rarely found within Canadian waters, and is not fished by Canadian tuna harvesters. | One of the smaller tuna species (40–100 cm length), but bigger than skipjack, but smaller than yellowfin tuna. Albacore tend to travel in single species schools. The Canadian fishery catches albacore mainly from the north Pacific stock. For Canadian harvesters, the albacore catch is valued at about $30 million each year. |
| Yellowfin | Bigeye |
|---|---|
 |  |
| Atlantic Bluefin (Thunnus thynnus) | Pacific Bluefin (Thunnus orientalis) |
|---|---|
 |  |
| The Atlantic Bluefin is the largest of the tuna species. It can reach 3 meters in length but the average size ranges between 80 and 200 cm. | When Bluefin tuna migrate into Canadian waters, Canada has more than 750 licensed Canadian harvesters who fish the western Atlantic bluefin tuna stock. For Canadian harvesters, the Atlantic Bluefin catch is valued at about $10 million each year. |
| Southern Bluefin (Thunnus maccoyii) |
|---|
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Sources:
International Seafood Sustainability Foundation (ISSF), About Tuna Species.
<https://iss-foundation.org/about-tuna/species/>