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Sea Creatures 101: The Life of Your Seafood: Tuna

© Sharon Rorem

Oh, I can hear the groans now-"TUNA?? How common! She must be running out of ideas!" Well, actually, the ideas CAN run a little thin sometimes, but when you think about it, what do you really know about tuna? What kind of life does a tuna live? How did it become such a common food fish?

Let's start with the life of the tuna first. Tuna are "pelagic" fish, drifting and following ocean currents. The currents in the ocean act like rivers, allowing the tuna to travel to places that are best suited for food and reproduction. When a tuna is ready to mate, it will swim through these "rivers" of current from deeper waters to reach open ocean or shallow coastal water, usually during August or late September. During spawning, a female lays her eggs in open water and a male releases sperm in the water near the eggs, fertilizing the eggs. After that, the baby tuna develop on their own without parental help. The eggs hatch in about 24 hours and the tiny tuna drift with the current. These tiny fish are easy prey for other fish. Out of a possible 6,000,000 eggs in a single spawning, about 2 of the tiny tuna will make it to adulthood.

Tuna are built for speed. The body is streamlined. The tail is sharply forked, and the tendons in it connect it to the swimming muscles, providing strength and force. The vascular system of the tuna keeps its body temperature above the water temperature. This helps to speed nerve impulses and increase power in the muscles. The shiny blue on top of the body and the gray-silver spotting on the bottom helps in camouflage. What do tuna eat? They aren't that picky-lobsters, crabs, shrimps, and barnacles. clams, snails, oysters and mussels, and even each other.

There are five general types of tuna: bluefin, yellowfin, bonito, striped (also called skipjack), and albacore. Bluefin tuna is the largest, weighing up to 18008 lbs. It can be found in the Atlantic and Pacific oceans, Mediterranean Sea, and the California coast. Yellowfin tuna is found in the Atlantic and Pacific, and near Florida and Rhode Island. Bonito (sometimes called bonita) grows to 6 lbs and lives in the Atlantic Ocean. It is often fished in Nova Scotia and Brazil. Striped tuna gets up to about 50 lbs. and can be found in the Pacific. Albacore, or "chicken of the sea", travels around a little more- migration is between the U.S. and Japan.