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November 2002
Wild shrimp are usually caught by trawling. That's a
fishing method in which large nets are towed through
the water or dragged along the seafloor. Trawl nets
scoop up everything in their path: shrimp, fish, sea
stars, even endangered sea turtles. Fishermen keep the
valuable shrimp, but often discard the other, unwanted
animals (known as "bycatch").
Shrimp trawl fisheries have among the world's highest
highest levels of bycatch. According to the U.S. National
Marine Fisheries Service, in the Gulf of Mexico, three
pounds of bycatch are caught for every pound of shrimp
that goes to market. According to the Worldwide Fund
for Nature, in the Gulf of Thailand it can be 14 pounds
of bycatch per pound of shrimp. The bycatch, crushed
in the net and then dumped on deck, is usually discarded
dead or dying. Sea turtles, already critically endangered,
have been killed by the thousands in shrimp trawl nets.
Concerns about bycatch have led fishermen to develop
devices they can put on their nets to reduce unwanted
catch. The "bycatch reduction device" (BRD) and the
Nordmore grate are net modifications that help fish
escape from shrimp nets. All U.S. shrimp trawlers—and
all foreign fleets selling shrimp in the U.S—are supposed
to outfit their nets with trap-door "turtle excluder
devices," or TEDs, to let sea turtles escape. However,
not every nation enforces TED use.
A better alternative is wild shrimp caught in traps.
This fishing method produces little bycatch; any unwanted
animals that end up in the traps can be released alive.
We consider trap-caught shrimp a "Best Choice."
What about farmed shrimp?
Most of the world's shrimp is farmed in Southeast Asia,
where valuable coastal wetlands, especially mangrove
forests, are often destroyed to create commercial shrimp
farms. This reduces habitat needed by juvenile fishes,
which means fewer fish for local people to catch for
their protein needs and fewer fish in the food web sustaining
marine life. Mangrove forests help shelter the coastline
from tropical storms, and when the forests are gone,
storm damage to coastal settlements is more severe.
Where shrimp are cultivated intensively, pollutants
and disease organisms build up in the muck beneath each
pond. After a few years, the pond can no longer support
healthy shrimp. The pond is abandoned and the farm must
expand to fresh territory. The contaminated muck cannot
support regrowth of the mangrove forest, so the ecosystem
will not recover for decades, if ever. While some countries
now have laws to protect their mangrove resource, shrimp
are so valuable on the international market that the
pressure to develop shrimp farms is still strong.
Some shrimp farms are environmentally friendly. They
are located inland, away from sensitive coastal habitat.
Water is recirculated, and wastewater is treated to
remove pollutants.
However, because there is currently no way for consumers
to tell the source of most farmed shrimp on the market,
we maintain a general recommendation to avoid farm-raised
shrimp from unknown sources.
Information courtesy of Monterey Bay Aquarium. Visit
their site. www.montereybayaquarium.org
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