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Life can sometimes get too intense for shrimp down on the fish farm.

Life Can Sometimes Get Too Intense For Shrimp Down on the Fish Farm

Taiwanese Black Tiger blight episode prompts some re-thinking on the long term merits of intensive aquaculture. But shrimp quality buying advice is main theme of SeaFare session.

Semi-intensive shrimp farming is "the best way to go," in light of the disaster that struck Taiwan's shrimp farms last year, according to Bill Felch of The New England Shrimp Co., Ayer, Mass.

"Shrimp, like human beings, can suffer from too much stress," he told a shrimp and shellfish panel at SeaFare '89, the International Seafood Exposition in Long Beach, Calif., U.S.A.

Apparently the shrimp in Taiwan suffered too much stress, due to overcrowding. Water quality and feed quality weren't what they should have been, Felch added; and when the blight struck, it was spread by the island's irrigation systems from farm to farm.

W.R. Grace, Inc., had the same problem at an experimental shrimp farm in Hawaii a few years ago, he noted. Water was kept running, and so were the shrimp, which were force-fed three or four times a day -- in the end, the shrimp couldn't take it any more, and succumbed en masse to infection.

Feeding intensively-farmed shrimp antibiotics isn't the answer, Felch said, because invertebrates are "bio-accumulators:" anti-biotics would become concentrated in their bodies, and passed on directly to humans consuming them (Use of anti-biotics in cattle feed has already generated a lot of controversy in the United States).

Whatever happened in Taiwan (the precise details still aren't clear), it virtually wiped out the harvest of black tiger shrimp, and sent the country's packers scurrying to the Philippines and elsewhere for shrimp to be co-packed under Taiwanese labels. Apparently they didn't find enough product, or at least enough good product to fill the gap: U.S. imports plummeted from 50 million pounds in 1987 to 10 million last year.

Felch's remarks on the Taiwan shrimp blight were actually an aside. His presentation, like most of those at SeaFare, was heavy in advice to buyers on shrimp quality. Tiger shrimp, for example, "can be the best you've ever eaten, or the worst," depending on how they're raised. If they aren't raised properly, they can be mushy in texture, and can take on a musty taste from eating algae instead of feed pellets. The brilliant orange or iridescent red stripes they take on when cooked make them look really spectacular, he said.

Peneids Dominate

Most commercially-harvested shrimp (80%) are tropical species, or peneids, recognizable by the fact that each segment overlaps the one behind it -- in fresh and coldwater (caradeid) species, the second segment overlaps both the first and the third. Deepwater tropical species which can be identified by a thick dorsal ridge and long swimmerets, tend to be mushy and have a high peel loss -- up to 30% of body weight, vs. 17-20% for most tropical shrimp. Rock shrimp in the Gulf of Mexico are typical of the sort: thick on shell, short on meat.

White shrimp account for most of the world harvest, and they look pretty much the same whether they come from the Gulf of Mexico, Ecuador or China. They don't have any grooves on their tail segments, unlike brown shrimp (bowed grooves), pink shrimp (parallel grooves) and spotted shrimp (shorter bowed grooves). Many buyers don't know how to identify shrimp, Felch complained; the actual "colors" are irrelevant, since these change from one environment to another -- it's the shells that count.

As in the case of tiger shrimp, however, species isn't everything. Coldwater shrimp can range "from tops to pits," Felch said. At its best, it has a sweet, lobster-like flavor, due to its diet. Greenlanders cook, peel and freeze such shrimp on board their fishing boats. But New England fishermen consider shrimp a by-catch; it just sits on their boats for a week or 10 days, and by the time it gets to port, digestive juices in the head have already gone to work -- you can spot the deterioration from a yellowing of the shrimp. Coldwater shrimp, moreover, have three-year life cycles, vs. a year for tropical shrimp, and can easily be fished out. McDonald's was victimized by this: it introduced a shrimp salad when coldwater shrimp were $2.65 a pound; then they went to $6.10.

What the Glaze Says

Shrimp buyers should check the glaze on frozen shrimp; if it's broken, the shrimp cna dehydrate. If you see black spots, it means that somebody let digestive juices dribble onto the shells when they cut the heads off. Dipping shrimp in a sodium disulfite solution will prevent this, but some boat owners don't want to bother -- they just shovel sodium disulfite onto the shrimp, then cover them with ice. Somebody with asthma could die from eating shrimp with too much of the chemical; fortunately, too much turns the shrimp a tell-tale yellow, and really high concentrations eat right through the shells, making them feel like sandpaper.

Some shrimp starts to cook right on deck if it isn't properly iced; the red tint is a dead giveaway. Shrimp "pieces" are any with less than five whole segments out of six. Sand veins in shrimp carry excrement, and should be removed from shrimp larger than 70 to a pound. The uniformity standard is a 1.5 ratio: in other words, the six or seven largest shrimp in a package shouldn't be any more than 1.5 times the size of the six or seven smallest. Sodium triphosphate, used to help shrimp maintain their natural moisture, can be used excessively to "pump up" shrimp; but such pumped-up shrimp will look suspiciously transparent. Fuel spills in a ship's bilge can give shrimp a petrochemical odor, and rotten egg and ammonia smells are both signs of deterioration: send those shrimp back to Davy Jones' locker.
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Title Annotation:includes related article on Taiwan's Black Tiger shrimp farms
Publication:Quick Frozen Foods International
Date:Jul 1, 1989
Previous Article:Japanese imports of marine products hit 2.4 million tons worth $8-billion.
Next Article:Pillsbury getting out of seafood; Bumble Bee, Van De Kamp's on block.

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