Foraging Ahead

tunacity

What is the fuss is over their taste, is it their metabolism, migration and demand in the world market, or just the fact that this fish is a substitute for the fat we miss in meat.

If not the migratory lifestyle, the high speeds and exceptional diet. The Bluefin swims with its mouth open feeding on the oceans best diet. The tuna prey on macrozooplankton and micronekton, mainly crustaceans, fish and cephalopods.

The Bluefin payoff is the amount of energy it receives per unit time, more specifically, the highest ratio of energetic gain (fitness) to cost while foraging in search of energy foods. A one metre tuna needs about 15 kilograms of live fish to put on one kilogram of fat, and about 1.5 to 2 tons of squid and mackerel are needed to produce a 100 kilogram bluefin tuna.

Tuna consumes as much as 5% of their body weight daily and must continually swim with their mouths open to force water over their gills, super charging their blood-rich muscles with oxygen. It is also said that Magnetite, a mineral found in neural pits in the tuna’s snout, may be used by the tuna to detect the earth’s magnetic field for navigation.

They are nomadic fish that have been tracked across entire oceans, tracked from California to Japan, and Pacific Bluefin tuna attains their internal heat production as high as mammals. Thus, they can maintain their cavity’s temperature when they foraging into colder environments.

Next time you sit down to enjoy sushi’s raw fish, think about it, the fish worked hard, swam across the ocean and was a global trotter finishing its way into a mouth.