SHRIMP

Marine shrimp is by far the most popular seafood in the United States. Boiled, fried, or stuffed, shrimp are delicious. They are high in protein and have many essential vitamins and minerals.

Many kinds of shrimp found in the Gulf of Mexico, however, only those of the family Penaeidae are large enough to be considered seafood. Brown shrimp (Penaeus aztecus), white shrimp (P. setiferus) and pink shrimp (P. duorarum) make up the bulk of Texas shrimp landings.

Shrimp are strange looking creatures. Their body is segmented and encased in a shell. The head spine, walking legs and antennae are attached to the head section, while the edible portion (the "tail") bears the swimming legs and tail fan. How these tasty crustaceans wind up on the dinner table or attached to the sportsmen's fish hook is an interesting story.

The life cycles of brown, white and pink shrimp are similar. They spend part of their life in estuaries, bays and the Gulf of Mexico. Spawning occurs in the Gulf of Mexico (a on the map). One female shrimp releases 100,000 to 1,000,000 eggs that hatch within 24 hours. The young shrimp develop through several larval stages as they are carried shoreward by winds and currents(b, c, and d). By the time the young shrimp (postlarvae) reach the gulf passes and enter the bays, they are one-fourth inch long, transparent and have a shrimp-like appearance (e).

Postlarvae drift or migrate to nursery areas within shallow bays, tidal creeks, and marshes where food and protection necessary for growth and survival are available (f). There they acquire color and become bottom dwellers. If conditions are favorable in nursery areas, the young shrimp grow rapidly and soon move to the deeper water of the bays (g).

When shrimp reach juvenile and subadult stages (3-5 inches long) they usually migrate from the bays to the Gulf of Mexico where they mature and complete their life cycles (h). Most shrimp will spend the rest of their life in the Gulf. The fishery for them begins when the shrimp are two to four months old and continues for the rest of their lives. If not caught by anglers or eaten by fish, they may live to be two years old.

To grow they must cast off their shell and form another. They get larger before the new shell becomes firm. Shrimp grow rapidly when the water is 68 degrees F and above. If bay water temperatures fall below 60 degrees F, shrimp growth is much slower and at temperatures below 40 degrees F mortalities may occur.

The Texas shrimp fishery is one of the most valuable and one of the largest seafood industries in the United States. The Texas Parks and Wildlife Department sells about 7,000 commercial shrimp boat licenses and about 2,000 noncommercial shrimp trawl licenses each year. Texas landings exceeded 73 million pounds of shrimp in 1989, worth more than 142 million dollars to the commercial fishermen.

Brown, white and pink shrimp harvested in coastal bays and in the Gulf, account for more than 80 percent of the Texas catch. The young use bays and begin entering the Gulf in late May or early June. If growth is fast, they may leave bays early; occasionally this happens after a warm winter.

White shrimp, which use bays during late spring, summer and fall, support a large fishery in bays along the upper coast and near-shore waters off the Gulf beach. They stay in bays longer and reach a larger size than brown shrimp and go to the Gulf as bays cool in the fall.

Pink shrimp, an important commercial shrimp in Florida and Mexico, are caught in Texas but do not represent a major part of the landings. They inhabit bays from late fall through early Spring, primarily along the middle and lower Texas coast.

Other shrimps of minor commercial value occur in the Gulf. Among these are the seabob, with its long head spine, the rock shrimp, with its hard outer shell, trachypenaeids, with their rough carapace, and a deep-water type called the royal red shrimp.

With few exceptions, shrimp are caught with trawls. These are winged nets that form a cone- like shape in the middle that tapers to a narrow end, called the cod-end. The two "wings" of a trawl are attached to wood "doors" weighted with metal "shoes" or runners. Lines run from the shrimp boat to each door. As the shrimp boat tows the trawl over the sea bottom, the trawl is held open by the kite-like spreading action of the doors. Shrimp and bottom fish scooped into the open trawl pile up in the cod-end. When the net is boated, a line that holds the cod-end closed is released and the catch falls to the deck. Next, shrimpers in the Gulf remove the heads (not allowed in Texas bays) before icing the meaty tails. The heads are thrown away.

Before Gulf shrimpers found out about trawling, they used long seines set close to shore and hauled by men or horses. Shrimp fishing was worthwhile only when white shrimp were abundant near the shore. By the 1940's, however, shrimp trawlers were a common sight at Gulf coast ports.

Once shrimpers were equipped with trawls, they could fish the dense shrimp stocks in deeper bay waters and the Gulf of Mexico. Improvements in transportation and refrigeration accompanied the growth of the shrimp trawl fishery and new markets opened. Today the modern Gulf trawler is a large, well-equipped seagoing vessel that can tow two or more large trawls at the same time.

Since red drum, spotted seatrout and many other saltwater gamefish like to eat shrimp, the sale of live shrimp to be used as bait by sport anglers is a big business. Bait shrimpers make 10 to 20 short tows a day often using small trawls.

Bait camp owners hold their live shrimp in watertight pens made of fiberboard, plywood or concrete. Small pens, 4x4x8 feet hold up to 30 to 80 quarts of shrimp. Large pens hold up to 100 quarts. To supply oxygen inside the pens, seawater must be pumped constantly into the pens. Many bait dealers have live boxes constructed of wire mesh over a sturdy frame submerged in shallow bay water and raised by a winch.

Continual success of the Texas shrimp fishery is a major responsibility of the Texas Parks and Wildlife Department. Coastal fisheries biologists, therefore, are involved in shrimp sampling programs designed to monitor the relative abundance and size of penaeid shrimp. These data can then be used to manage the fishery effectively.

Using information collected over the past twenty years, management biologists were able to detect changes in the shrimp population from the heavy fishing pressure seen in the last few years. These changes showed a population that was being stressed from overfishing. As a result, the 74th Legislature created a limited-entry fishery for shrimping in Texas waters that determines eligibility for obtaining a shrimp license. Implementing this legislation should improve the overall health of the shrimp population and the stability of the shrimp industry.

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