Cannibal shrimp, officially known as Asian tiger shrimp, have been found before in U.S. waters over the last decade, but those sightings have been in small numbers while the cannibal shrimp are 10 times more prevalent now, according to the U.S. National Oceanic and Atmospheric Administration, or NOAA.
And they are probably even more prevalent than reports suggest, because the more fisherman and other locals become accustomed to seeing them, the less likely they are to report them, Pam Fuller, a U.S. Geological Survey biologist, told CNN.
The Asian tiger shrimp, which can grow to be 13 inches long, preys on its shrimp brethren, resulting in the term cannibal shrimp.
Female cannibal shrimp can lay 50,000 to a million eggs that can hatch within 24 hours.
Researchers will be studying how harmful the cannibal shrimp are and whether they carry diseases, among other things.
Researchers from the U.S. Geological Survey (USGS) and NOAA are now working with state agencies from North Carolina to Texas to look into whether these shrimp carry disease, compete for the same food source, or prey directly on native shrimp, NOAA said. An investigation is also underway to determine how this transplanted species reached U.S. waters, and what is behind a recent rise in sightings of the non-native shrimp.
Scientists do not know how the Asian tiger shrimp found their way to U.S. waters.
It's possible the cannibal shrimp escaped from aquaculture facilities, NOAA postulated, but there are no known Asian tiger shrimp farms in operation in the United States.
Other hypotheses include that the shrimp came to U.S. waters via ballast water from ships or that ocean currents drifted the shrimp from the Caribbean or Gambia.
Scientists from NOAA and the USGS will be looking at shrimp from the Gulf and Atlantic coasts to look for subtle differences in their DNA, information which could offer valuable clues to their origins.
This is the first look at the genetics of wild caught Asian tiger shrimp populations found in this part of the U.S., and may shed light on whether there are multiple sources, NOAA said.
Whenever a species shows up in an area that is not part of their native habitat, scientists get concerned.
As with all non-native species, there are concerns over the potential for novel avenues of disease transmission and competition with native shrimp stocks, especially given the high growth rates compared with other species, NOAA said.
About 2,000 cannibal shrimp were accidentally released from a South Carolina acquaculture facility in 1998, according to CNN.
Roughly 300 cannibal shrimp were found in South Carolina, Georgia and Florida after the accident.