National Geographic : 1957 May
705 Two "Barn Doors" Are the Net's Steel-bound Jaws. They Hold the Trawl Open Shrimpers off Texas and Mexico scrape the bottom with nets more than 100 feet wide. Dragging immense swaths for hours at a time, they scoop up virtually everything in their paths. Smaller, more selective nets used in Florida waters bring up a higher proportion of shrimp to trash. A trawl owes its efficiency largely to its doors, or otter boards. Rigged with chains at the mouth of the net, they move through the sea like a pair of opposing kites. Water pressure forces them apart, spreading the net wide. they remind me of water fleas. It's hard for a layman to tell them from baby sailfish or mullet.* Eventually, those shrimp that survive move seaward again, migrating back to the spawn ing grounds. It appears that most adult shrimp spawn only once and that their life span is only one year. What science knows of shrimp comes chiefly from studies of white shrimp, which domi nated the industry until 1950. These burrow into the bottom mud by night and come out by day. But the two "new" species of grooved shrimp do just the reverse. Exactly why, we don't yet know. Shrimp not only delight the gourmet's taste; they are one of the most nutritive foods known to man. The edible part of shrimp is largely protein; fat content is re markably low, less than one-half percent by weight. Like most sea food, they contain a lot of iodine, plus vital minerals such as calcium, magnesium, phosphorus, and iron. For best flavor and enjoyment, shrimp must be fresh, or quick-frozen while still fresh from the sea. With trawlers staying out much longer, the problem of keeping shrimp fresh aboard the shrimp boats themselves has grown acute. One day at the Marine Laboratory my phone rang, and a friend said, "I've just bought the Sachem, an old shark hunter. I'm converting her to a freezer boat to fish Cam peche, and I want to avoid carrying ice to chill the shrimp until I can get them into the freezer. Will they stay fresh in chilled water?" "I don't know," I said, "but we'll try to find out." A series of experiments proved that shrimp could be kept fresh as long in chilled sea * See, in the NATIONAL GEOGRAPHIC MAGAZINE: "Strange Babies of the Sea," by Hilary B. Moore, July, 1952, and "Solving Life Secrets of the Sailfish," by Gilbert Voss, June, 1956.