Mention the Great Lakes, and Asian carp will most likely enter the conversation. “Asian carp” is a general term used for four species of carp—bighead, silver, black, and grass—that originated in Asia and were imported to the southern United States in the 1970s to support aquaculture. Fast-forward several years, and bighead (Hypophthalmichthys nobili) and silver (H. molitrix) carp entered the Mississippi River, where they have thrived. Due to their voracious appetites for plankton (also consumed by native fish), their rapid rate of reproduction, and their relatively large size, Asian carps have had devastating impacts on native fish populations. Today, bighead and silver carp are the dominant fish species in the Illinois River, which connects the Mississippi River to Lake Michigan. There is concern that if bighead and silver carp enter the Great Lakes, they may cause significant ecosystem damage.
NOAA is currently contributing to vital research on Asian carps’ prospects for survival in Great Lakes water. Prior to starting our study, preliminary research suggested that bighead and silver carp would have limited distribution in the Great Lakes and a relatively small impact on the lakes’ food webs, despite being dominant in the Mississippi and Illinois Rivers. However, these studies tended not to account for many variables that could influence the species’ growth and survival. Moreover, very few Great Lakes-based studies documented Asian carps’ impacts on other fish or fisheries or considered the potential for native fish species to prey on bighead and silver carp and thus control their population.
NOAA aims to fill these research and knowledge gaps. With the support of the GLRI, we have partnered with the US Fish & Wildlife Service, the Cooperative Institute for Great Lakes Research (CIGLR), and Australia’s CSIRO Division of Marine and Atmospheric Research to more precisely identify the risks that Asian carp present to the Great Lakes and forecast their potential entry into the ecosystem.
We are using ecosystem models, including the Atlantis Ecosystem Framework and an “individual-based” model that accounts for specific fish in multiple lake locations. With these models, we can make projections about the minimum numbers of bighead and silver carp required to maintain a viable population in the Great Lakes’ diverse habitats—and the projected impact of Asian carps on native fish populations and food webs. Essential variables such as nutrient inputs, geochemical processes, water temperature, zooplankton and phytoplankton densities, current fish communities, and climate change scenarios are being incorporated into models and forecasts. We believe that accurate, scientifically-driven forecasts of the ecological requirements and impacts of Asian carp will promote better policies regarding these high-profile invasive species.
GLRI Funding:
FY 2011: $701,000
Contacts:
ed.rutherford@noaa.gov and doran.mason@noaa.gov