Asian tiger shrimp (Penaeus monodon) are native to Indo-Pacific, Asian, and Australian waters, but are now found along the Atlantic Bight and Gulf coasts of the United States. These shrimp-known for their distinctive black stripes-can measure up to 12 inches long and weigh nearly a pound. Asian tiger shrimp have voracious appetites, feeding on native shrimp, bivalves, crustaceans, and fish. This appetite may upset local ecosystems, as well as the U.S. shrimping industry. To learn more about this invasion, government scientists are trying to determine the pathway of introduction, where they are established, and what this may mean for native fish and other organisms.
Asian tiger shrimp have been detected in U.S. waters since 1988, but their numbers have been on the rise in recent years. How they first arrived is still unknown; however, a recent article in the journal Aquatic Invasions suggests three possible sources: 1) the release of larvae from ballast water, 2) migration from wild populations in the Atlantic or Caribbean Sea, or 3) escape from aquaculture facilities. Researchers from NOAA and the U.S. Geological Survey are working with state agencies along the Atlantic and Gulf coast to pinpoint how this animal was transplanted into U.S. waters.
"We can confirm there was nearly a tenfold jump in reports of Asian tiger shrimp in 2011," explained Pam Fuller, the USGS biologist who runs the agency's Nonindigenous Aquatic Species database and lead author of the 2014 article in Aquatic Invasions. "And they are probably even more prevalent than reports suggest, because the more fishermen and locals become accustomed to seeing them, the less likely they are to report them."
Fuller's team at USGS has been tracking reports of Asian tiger shrimp since they first came to the attention of marine scientists in 1988, when nearly 300 of them were collected off the coasts of South Carolina, Georgia, and Florida within 3 months. Scientists tracked them back to an aquaculture facility operating at that time in South Carolina that accidentally released an estimated 2,000 Asian tiger shrimp. It was not until 18 years later that reports of the non-native shrimp resurfaced.
To better understand where this resurgence came from, USGS and NOAA scientists are examining shrimp collected from the Gulf and Atlantic coasts to look for differences in their DNA-information that could offer valuable clues to their origins. This work might shed light on whether multiple sources are contributing to the new invasion.
"We're going to start by searching for subtle differences in the DNA of Asian tiger shrimp found here-outside their native range-to see if we can learn more about how they got here," said USGS geneticist Margaret Hunter, co-author of the article. "If we find differences, the next step will be to fine-tune the analysis to determine whether they have multiple populations, or are carried in from outside areas."
Ongoing studies to examine the environmental DNA of Asian tiger shrimp in the southeast United States will help determine the extent of the invasion. Finding eDNA in the water will help researchers quickly locate new populations-especially populations of smaller individuals that are less likely to show up in commercial trawl nets. This is the same technology being used to track the spread of Asian carp in the Mississippi River and Great Lakes basins.
NOAA, USGS, and state scientists are also investigating the biology of these shrimp as it differs from native shrimp species. As with all non-native species, there are concerns over the potential for new avenues of disease transmission and competition with native shrimp stocks, especially given their high growth rates and spawning rates compared to other species.
"The Asian tiger shrimp represents yet another potential marine invader capable of altering fragile marine ecosystems," said James Morris, marine ecologist at NOAA and co-author of the Aquatic Invasions article. "Our research efforts include assessments of the biology and ecology of this non-native species. We're also working to predict impacts to economically and ecologically important species of the Atlantic and Gulf of Mexico." Together, federal and state agencies are working hard to understand the spread and ecological impacts of this new invasive species in U.S. waters. Information gained from this invasion may help us identify ways to prevent the next one. Prevention of invasive species continues to be the best way to avoid the costly economic and ecological consequences associated with their establishment.
