slow to reproduce, and there are already signs
that its numbers have been dangerously
depleted by overfishing.
Tunas and Mackerel
Who would know from looking at a cheap can
of tuna that it was made from one of the most
remarkable fish on earth? The tunas are large
predators of the open ocean, reaching 1,500
lb/680 kg and swimming constantly at speeds
up to 40 miles/70 km per hour. Even their
fast-twitch muscle fibers, which are normally
white and bland, contribute to the nonstop
cruising, and have a high capacity for using
oxygen, a high content of oxygen-storing
myoglobin pigment, and active enzymes for
generating energy from both fat and protein.
This is why tuna flesh can look as dark red as
beef, and has a similarly rich, savory flavor.
The meaty aroma of cooked and canned tuna
comes in part from a reaction between the