Asian tiger shrimp: Love them or fear them?
By BRAD RICH
Reprinted from the Tideland News
official: The influx of Asian tiger shrimp into North Carolina waters,
the rest of the South Atlantic coast, and the Gulf of Mexico is
significantly worrisome, if not downright frightening.
James Morris, a marine ecologist at the National Oceanic and
Atmospheric Administration’s Center for Coastal Fisheries and Habitat
Research in Beaufort, said recently that a report from the U.S.
Geological Survey indicated that the numbers of the jumbo shrimp, which
can grow as long as 13 inches, increased tenfold between 2010 and 2011.
that trend continues this year, we’ll be able to say we’re certain this
is truly an ‘invasion,’ that these shrimp are self-reproducing, not
just a one-time pulse,” Morris said. “It’s looking serious. If it keeps
up, we’ll reach a ‘point of no return.’ There could be significant
implications, including possible disruptions in the food web.”
USGS survey notes that watermen brought in only 32 of the Asian shrimp
in 2010, but caught 331 in 2011. Experts say the population is probably
far higher than those numbers indicate, as fishermen generally report
sightings and catches less often as they become more familiar with the
tiger shrimp first came to widespread attention in North Carolina late
last summer, when Sam Meadows, a commercial fisherman in Cedar Point in
Carteret County, caught about 35 in the Cape Fear region and off the
South Carolina, between Georgetown and Charleston. Others were caught
in Pamlico Sound.
Meadows ate one back then.
prefer our domestic shrimp, maybe just because that’s what I’m used
to,” he said. “But it was good; it tasted like shrimp. And if somebody
who didn’t know our shrimp ate one, he probably wouldn’t notice
anything, except that it’s a little tough. And believe me, it’s a
of the crustaceans, which to the untrained eye look more like lobster
than the shrimp species native to North Carolina waters, were more than
a foot long. And they’re black-and-white striped, hence the tiger name.
the population is growing because of reproduction, not because the
shrimp are moving in from other waters, Morris said there is almost no
chance the species could be eradicated.
don’t think it would be possible, not in my opinion,” he said. “We just
don’t have the biotechnology tools to do that, like we do with ‘pests’
in agriculture. I always like to be optimistic, and maybe those tools
could be developed, but it would many years and a lot of money for
one, Morris said, can be sure yet how the tiger shrimp will affect
North Carolina’s prized native shrimp. Millions of pounds are caught
and sold each year, and Morris called the population “robust and
dynamic.” But, he added, shrimp are an annual crop, and the population
is heavily dependent upon environmental factors, such as rainfall.
Shrimp like high salinity levels, and heavy rainfall in the spring can
decrease salinity and affect the shrimp crop significantly.
other words, if the tiger shrimp reproduce well and the native shrimp
don’t, there’s no telling what could happen; the answer, Morris said,
will come, if it comes at all, with continued research and ecological
In the end, we all might do well to learn to love our new shrimp.
with the impact, the question of exactly how the tiger shrimp got here
is, for now, unanswered. Though there is speculation it might have
arrived via ocean currents after being released from aquaculture
operations in the Caribbean or in ballast water in a ship, Morris said
the ultimate answer might come from genetic research, using DNA.
the USGS announced the results of its comparative surveys of 2010 and
2011 tiger shrimp catches, headlines in some media have been alarming.
One, for example, brought to mind Japanese horror films about Godzilla
and other mutant creatures: “Giant Cannibal Tiger Shrimp Are Taking
Over U.S. Waters.”
said it’s true that the tigers do eat other shrimp, but so do other
shrimp, not to mention fish. The difference is the Asians are larger
and eat more.
are no more carnivorous than other shrimp,” Morris said. “But if those
kinds of headlines catch the eye and then people read the stories and
learn more about invasive species and why they are bad, then I don’t
really mind. Maybe this will help people learn a lesson.”
Morris added that officials have been monitoring the tigers, which can weigh over a quarter of a pound, since at least 1998.
are native to the Indo-West Pacific, where, they’re a common
aquaculture species, with worldwide production in 2009 coming in at
770,000 tons valued at over $3.5 billion.
a huge industry; the entire U.S. domestic commercial fishing industry
in 2010 landed 8.2 billion pounds of seafood, worth $4.5 billion,
according to NOAA figures. In 2010, North Carolina commercial fishermen
landed 5.45 million pounds of all species of shrimp, worth $10.7
million, according to fisheries division statistics. Only about 10
percent of the shrimp consumed in the U.S. each year are caught or
Murphey, the state Division of Marine Fisheries district biological
supervisor in Morehead City, last year said the division is concerned,
but added that it’s too early to tell if there is or will be a problem
with the tiger shrimp here. She said she didn’t think tiger shrimp were
being raised anywhere in the United States, let alone North or South
Carolina, and added that any such operation would require a state
permit. Most of the North Carolina tiger shrimp reports, she said, came
after Hurricane Irene hit the area in late August.
of the tigers aren’t really expected until later in the summer and into
fall, but anyone who catches one is urged to save it and contact the
division. Fishermen should freeze the shrimp, record the date and
location the shrimp were taken, and contact Murphey by phone at
800-682-2632 or by email.
She is also interested in knowing if the shrimp were caught in a trawl, a skimmer, a cast net or by another method.
(This story is provided courtesy of the Tideland News, a weekly newspaper in Swansboro.)