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Statement of Dr. Leon Carl, Regional Executive for the Midwest Area, U.S. Geological Survey

February 25, 2010

Before the Senate Committee on Energy and Natural Resources, Subcommittee on Water and Power on the science of Asian carp and efforts to prevent their introduction to the Great Lakes.

Statement of Dr. Leon Carl

Midwest Area Regional Executive, U.S. Geological Survey

Department of the Interior

Before the Senate Committee on Energy and Natural Resources

Subcommittee on Water and Power

Oversight Hearing on Science and Research on Asian Carps

February 25, 2010


Chairwoman Stabenow and members of the Subcommittee, I am Leon Carl, Regional Executive of the U.S. Geological Survey (USGS) Midwest Area. Thank you for the opportunity to testify on the Department of the Interior’s (Department) efforts regarding the science and research on Asian carps in support of the Federal Asian Carp Control Strategy Framework (Framework) to prevent the establishment of Asian carps in the Great Lakes.  Also included in this statement is a summary of on-going Department efforts to address other aquatic invasive species in the Western United States (U.S.).

The USGS, the science arm of the Department, conducts research to understand the interrelationships among earth surface processes, ecological and biological systems, and human activities.  In support of the science, the USGS partners with other Federal and State agencies, tribal governments, and non-governmental organizations to provide the science needed to help resource managers address critical and complex natural resource issues.

Today, my testimony will provide background on the biology of Asian carps, explain the Department’s response to growing threats from bighead and silver carps, and describe what we are learning about these fishes as they became established and abundant in the great rivers of the central U.S.  I will end by describing on-going and new USGS research efforts to address the threat of Asian carps to the Great Lakes using the newly drafted Framework.




Bighead and silver carp (collectively referred to as “Asian carps”) filter bacteria, algae, and zooplankton from the water column—elements at the base of aquatic food webs.  Asian carps were imported into the U.S. in the early 1970s as biological control agents for nuisance algal blooms in wastewater treatment plants and aquaculture ponds, as well as for human food.  They escaped from those uses, were first captured in the wild in the 1980’s, and quickly became the most abundant large fishes in parts of the Missouri, Illinois, and Mississippi rivers.  Both bighead and silver carps grow quickly and become large as adults, often averaging about 10 pounds in U.S. rivers.  Records for both species approach 100 pounds, but in the U.S. silver carp over 20 pounds and bighead carp over 30 pounds are uncommon.  Schools of silver carp often jump from the water, particularly in response to passing motorboats, sometimes reaching heights of 10 feet in the air.  When jumping silver carp intersect with boaters or boat equipment, serious injuries or damage can result. 


Through time, Asian carps have steadily moved upstream through the Illinois and Des Plaines rivers into the Chicago Area Waterway System (CAWS).  Because of the propensity of these fishes to outcompete native fish species in ecosystems they invade, great concern exists over the possibility of Asian carps colonizing the Great Lakes. Their establishment could threaten an important recreational and commercial fishery (valued at over $7 billion dollars annually) and the well-being of native species. 


Growing Asian Carp Concerns


The Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 established the Aquatic Nuisance Species Task Force (ANSTF), an intergovernmental entity including the U.S. Fish and Wildlife Service (Service), USGS, National Park Service, Bureau of Land Management, and Bureau of Reclamation within the Department, five other Federal agencies, and 12 Ex-officio members.  The ANSTF is co-chaired by the Service and the National Oceanic and Atmospheric Administration and encourages Federal and State agencies to establish partnerships to augment work with partners to enhance collective efforts to address aquatic invasive species issues.


In response to threats from Asian carps, the ANSTF established an Asian Carp Working Group in 2003.  Led by the Service, this stakeholder group of private and public sector fisheries professionals, aquaculturists, and aquatic ecologists developed a comprehensive national Asian carp management and control plan.  The final plan, Management and Control Plan for Bighead, Black, Grass, and Silver Carps in the United States, was approved in 2007 and included input and authorship from several USGS scientists.  Most USGS research on Asian carps has focused on national goals to reduce feral populations, conduct research to provide accurate and scientifically valid information for effective management and control, and to effectively plan, implement and evaluate the management and control of bighead and silver carps.


Role of the U.S. Geological Survey


The USGS has been the primary Federal agency conducting ecological research on Asian carps for the past decade. USGS scientists have participated in various interagency efforts during this time including assisting in the development and writing of the national Asian carp management and control plan, participating in the interagency Asian Carp Rapid Response Team, organizing research symposia focused on Asian carps, and have been involved in local and regional research and control planning efforts. The two main USGS science roles in regard to Asian carps have been to track and report their geographic distribution in the U.S. and to provide research to improve understanding of the biology of these fishes in U.S. ecosystems to better manage populations. 


Monitoring the Distributions of Asian Carps in the U.S.


The USGS has been involved in monitoring the geographic distribution of Asian carps since they became abundant in the Mississippi River drainage.  The primary means of delivering distributional data on invasive aquatic species is the USGS Nonindigenous Aquatic Species database (  The database was created by the ANSTF with the goal of providing timely, reliable data about the presence and distribution of nonindigenous aquatic species using a National Nonindigenous Aquatic Species Information Center with: (1) a data repository and geographic information system; (2) a mechanism to allow sources such as researchers, field biologists, anglers, and others to report detection and occurrences of nonindigenous aquatic species; (3) transfer of information to interested parties; and (4) rapid communication of oral and written information. Real-time maps can be produced by users with the most recent distributional data reported.  These maps are widely used by our partners and are frequently used by various media.  The NAS database is perceived as a valuable resource by our partners and reporting distributional information on Asian carps to the NAS database is an objective in the Management and Control Plan for Bighead, Black, Grass, and Silver Carps in the United States.


The USGS continues to collect valuable distributional data on Asian carps as part of the Long Term Resource Monitoring Program (LTRMP), which is implemented by USGS in cooperation with the five Upper Mississippi River System (UMRS) States (Illinois, Iowa, Minnesota, Missouri, and Wisconsin), and with guidance from the U.S. Army Corps of Engineers.  LTRMP personnel collect data on water quality, aquatic plants, macroinvertebrates (e.g., larval insects, worms, crayfish), and fisheries throughout the year using standardized protocols across six study reaches in the UMRS.  The objective of the LTRMP Fisheries Component relates to collecting quantitative data on the distribution and abundances of all fishes and communities in the UMRS. Therefore, protocols are not specific to Asian carps.  Much useful data on the presence and abundance of these fishes has been collected, however, and these data continue to be reported to the NAS database and used by partners.


Highlighted USGS Research on Asian Carps in U.S. Waters


In 2002, Congress petitioned the Service to list black, bighead, and silver carps as Injurious Wildlife under the Lacey Act.  To help the Service address the petition, USGS collected and interpreted publications on the basic biology, life history, uses, and history and consequences of their introductions around the world, and developed an environmental risk assessment for the U.S. that led to the publication of Bigheaded Carps: A Biological Synopsis and Environmental Risk Assessment.  This report, later published as a book, synthesized and interpreted information and data on bighead and silver carps from scientific literature from around the world and made it more accessible, and is seen as a foundation for understanding the biology of these fishes both in their native ranges and as invaders in U.S. rivers.


When USGS researchers began studying Asian carps in U.S. waters, not enough was known about their basic biology to use traditional fisheries management tools.  For instance, a basic tool of fisheries management is to model population growth.  To develop a population model, some basic parameters must be known, such as body length of the species at known ages and the number of offspring produced.  In the case of Asian carps, these parameters could not be estimated because not enough was known about Asian carps to even collect these data.  Throughout the world many different anatomical structures of bighead and silver carps have been used for aging individual fish but there had not been a comparison of methods to determine the most reliable.  USGS researchers collected a wide variety of aging structures from known-age fish and conducted such a comparison.  Data analysis is still ongoing in this study, but it is clear that some structures provide more reliable age estimates than others.  In gathering data from sources around the world, it became apparent that the timing and frequency of spawning of bighead and silver carps varied widely.  Estimating the number of offspring an individual female could produce for population modeling requires data on the timing and frequency of spawning.  USGS researchers completed such a study on Asian carps in the Missouri River and found that the spawning time of these fishes was much longer in their introduced ranges than in their native ranges and that individual females can have multiple spawns of portions of their eggs over that extended period of time.


A fundamental understanding of Asian carp biology and life history requirements in U.S. waters underpins nearly all other areas of potential research to manage and control these species and completing key basic biological studies on Asian carps has been an early research focus of USGS.  For example, one study examined the diet and diet selectivity of bighead and silver carps in the Missouri River and one of its tributaries. Another, a 2-year telemetry study examined the movements and habitat selection of bighead and silver carp captured from the Missouri River and a prominent tributary.  As part of this study, side-scan sonar was used to image and map available habitats of the tributary.


Predicting the potential range of an invading species can help guide monitoring efforts of natural resource agencies.  Therefore, gaining an understanding of factors limiting distribution can prove valuable for natural resource managers.  Water hardness has been proposed as a factor potentially limiting the distribution of Asian carps.  If true, water hardness could be used to predict areas in which Asian carps could and could not survive. However, studies by USGS scientists have shown that bighead and silver carp egg survivorship is not substantially affected by water hardness suggesting that this factor would not be helpful in predicting potential distribution.


Results from diet studies indicate that excessive filtering by Asian carps can affect native fishes. In a collaborative study between Florida State University and USGS examining diets of Asian carps and native filter feeding fishes found substantial dietary overlap between bighead carp and both bigmouth buffalo and paddlefish. Similar dietary overlap was found between silver carp and gizzard shad, suggesting competition between these species could occur when food resources are limiting.  Preliminary results from a study in which USGS is a participant with many partners indicate that excessive filtering by Asian carps can even affect Asian carps.  Data from this study indicate that Asian carps are quite robust when they first invade an area, but that they become thinner after they have been established for a few years. 


While conducting initial field research on Asian carps to understand their fundamental biology, USGS researchers also initiated two studies to assess efficacy of traditional fisheries management chemicals on controlling Asian carps.  Both studies found that the susceptibility of Asian carps to rotenone and antimycin were similar to those of native fishes.  Results of these studies helped inform development of the Asian Carp Rapid Response Plan, which was implemented in December 2009 to poison a 5.7-mile stretch of the CAWS when the electrical barrier (Barrier IIA)  in Romeoville, Illinois, was de-electrified for scheduled maintenance.


The USGS also completed initial experiments to determine whether naturally-produced Asian carp pheromones could be used to better control the distribution or reduce the population sizes of these fishes.  For instance, many members of the minnow and carp family are known to have alarm pheromones that are released from traumatized skin and cause an alarm reaction in members of the same or closely-related species.  In preliminary laboratory studies, juvenile bighead and silver carps exhibited a significant avoidance of skin extracts from members of their own species.  Alarm pheromones could potentially be introduced into areas near locks to keep Asian carps from entering into these structures and gaining access to additional areas to colonize.


The USGS researchers also conducted a study to support an objective of the Management and Control Plan for Bighead, Black, Grass, and Silver Carps in the United States that encourages the development of markets for bighead and silver carp flesh.  Ensuring safety of consuming flesh of Asian carps is paramount to this objective.  USGS collaborated with the Saint Louis Zoo to collect bighead and silver carps from the Missouri River and to analyze tissues for organic and inorganic contaminant concentrations.  Data analysis revealed contaminant concentrations lower than in native fish from the same area and acceptable for human and animal consumption.


New USGS Projects on Ecological Effects of Asian Carps in the Mississippi River Drainage


As research on Asian carps in the Mississippi River drainage has progressed from basic to more complex research questions, additional effort has been placed on examining ecosystem level effects of these fishes.  In FY10, USGS has two new studies looking at more complex ecological interactions of bighead and silver carp on large river ecosystems.


The first study will examine whether excessive filtering of planktonic resources by Asian carps has altered the flow of essential fatty acids in the Upper Mississippi River System to such an extent that these effects are cascading through different trophic levels of the ecosystem.  Specifically, this pilot study will determine if the abundance and quality of food resources for aquatic waterfowl have been affected by filter feeding by Asian carps.


A second study will seek to determine the mechanism by which Asian carps negatively affect fishes with larvae that share open water areas with feeding Asian carps. It is unclear if the observed negative effects are due to competition for food resources or if the Asian carps are actually eating larval fishes.  To examine this phenomenon further, USGS researchers will determine whether bighead carp can prey effectively on larval fish when the larvae of native fishes are present in relative abundance using genetic barcodes. 

USGS and the Asian Carp Control Strategy Framework

The USGS is identified as the lead agency to address nine of the 31 action items in the Framework. One action focuses on preventing further spread of Asian carps; two more actions will aid in Asian carp early detection and rapid response efforts; another will assess the effects of bighead and silver carps on plankton resources in the Great Lakes, and five additional actions will focus on developing control strategies for Asian carps.

Short-term Action 2.2.7 addresses preventing further spread of Asian carps in the U.S. This research project will identify other pathways in addition to the CAWS that could allow even intermittent water flow between the Mississippi River watershed and the Great Lakes resulting in the exchange of species between basins.  The USGS will work with the U.S. Army Corps of Engineers and other partners to help identify these places and the hydrologic conditions during which invasive species could be transferred.


Two USGS action items in the Framework address Early Detection and Rapid Assessment (EDRA) of Asian carps.  Short-term Action 2.1.11 will build on preliminary screening of tributaries of the Great Lakes identified in earlier USGS research as potentially supporting spawning of Asian carps.  This research project will further refine predictions about suitable spawning locations in the Great Lakes for these fishes.  Speculation exists as to whether adequate plankton resources are available in the Great Lakes to sustain Asian carps.  Anecdotal evidence suggests that these fishes are more flexible in their feeding methods than previously believed and understanding their ability to use a variety of food resources is important in understanding where these fishes may be able to survive in the Great Lakes.  Short-term Action 2.1.12 will examine the ability of bighead and silver carps to use food resources in addition to plankton.  


Intensive filtering of planktonic resources by bighead and silver carps can lead to dramatic changes in those communities.  One potential outcome observed in the literature is an increase in toxic bluegreen algae blooms. Long-term Action 2.2.14 will examine the potential ecosystem-level effects of bighead and silver carps on toxic algal blooms in the Great Lakes.


Three of the USGS action items in the Framework involve developing species-specific chemical control methods for Asian carps.  The primary chemical control project is Short-term Action 2.1.6.  No method currently exists to control Asian carps or quagga and zebra mussels without treating the entire water column and euthanizing all fish and likely all mussels in the area treated.  In this project, USGS will investigate the feasibility of using recent advances to incorporate toxins or bioactive compounds into a targeted oral delivery platform to achieve species-specific control.  USGS researchers have developed a Cooperative Research and Development Agreement with a private company, Advanced Bionutrition Corporation, to use their patented oral delivery platform.  Using this technology, fish toxins, perhaps rotenone, would be encapsulated into a neutrally-buoyant molecule of the preferred size filtered by bighead and silver carps.  The molecule would remain safe and stable until the toxicity is triggered by something unique in the physiology of the targeted species, perhaps mucous on the gill rakers or the pH of the gut of bighead and silver carps.  Delivering toxic doses of chemicals to Asian carps or zebra and quagga mussels in this manner would not only allow for species-specific control, but would require the release of lesser amounts of chemicals into the environment.  This project is supported by Short-term Action 2.1.10.  In one additional action item, Short-term Action 2.1.8, USGS researchers will work with a pharmaceutical or agrochemical company to identify chemical toxicants that may be specifically toxic to bighead and silver carps. Once identified, these chemicals would be tested on Asian carps as well as native fishes to examine selectivity.

Preliminary research completed by USGS researchers on Asian carp pheromones showed promise in using these compounds to either attract or repel bighead and silver carp from specific areas.  Using pheromones in combination with other control methods may provide substantial efficiency and efficacy in achieving population control.  Short-term Action 2.1.7 will allow USGS to further pursue the feasibility of exploiting Asian carp pheromones to enhance containment or control efforts.

The last USGS action item identified in the Framework is Action 2.1.9. This research project evaluates whether it is possible to disrupt spawning behaviors of bighead and silver carps using sound waves.  Sound waves of particular amplitudes and frequencies can alter fish behavior.  This project will identify sound wave amplitude and frequency that elicit silver carp avoidance behavior to disrupt spawning aggregations and limit recruitment.

Highlights – Bureau of Reclamation Invasive Species Program

 Reclamation has been active in a wide-range of efforts to combat invasive species that impact the management of our facilities or cause damage to habitats.  Reclamation is concentrating on ways to prevent invasive species infestation, develop early detection/rapid response measures, support control and management actions, conduct targeted research, restore habitats damaged by invasive species, extend outreach to the public, and strengthen coordination with our managing partners.  

For example, in Arizona and California, Reclamation partners with the U.S. Fish and Wildlife Service, other federal and state agencies, and the Palo Verde Irrigation District to control invasive aquatic weeds such as giant salvinia and parrotfeather.  In California, Reclamation cooperates with the State agencies on hydrilla control.  Approximately 450 acres of hydrilla have been controlled, and over 3,000 acres of ponds, canals, and rivers have been surveyed.  In New Mexico and Arizona, Reclamation participates in the Multi-Species Conservation Program by controlling nonnative fish to benefit threatened and endangered native species.  In several states and in collaboration with other agencies, Reclamation is performing research and demonstrating control and habitat restoration of salt cedar infested areas.  In Washington State, Reclamation is conducting habitat restoration along the Yakima River.

Reclamation’s greatest invasive species challenge is limiting zebra and quagga mussel introductions into the western states.  These mussels arrived in the United States from Europe in the 1980s and spread to many Eastern state waterways.  They have now spread into the Western states and as a result, Reclamation is concentrating on proactive measures, in close coordination with other Federal, state, and local entities, to help reduce the post-introduction spread and impacts of mussels at Reclamation facilities.  An invasive mussel corporate task force has been established across Reclamation to focus on the development and implementation of a four-part strategy both on a regional and a Reclamation-wide basis. Reclamation has continued investigations to develop and implement facilities protection technologies (filtration for cooling water systems, biologically based pesticide product, and coating systems to minimize or prevent mussel attachment to critical infrastructure).

Reclamation received funding through the American Recovery and Reinvestment Act (ARRA) of 2009 which will be expended for monitoring and detection at high priority water bodies in the western U.S. Nearly 200 reservoirs will be studied.  Early detection of mussels enables facilities protection actions before impacts to infrastructure and water resources are realized. 

Reclamation has developed an Equipment Inspection and Cleaning Manual which emphasizes prevention through inspection and cleaning of various types of equipment.  Reclamation has also developed a comprehensive Integrated Pest Management Manual to assist field personnel in diagnosing and treating pest and invasive species problems.  Reclamation has provided leadership to develop the Quagga-Zebra Action Plan (QZAP) for the Aquatic Nuisance Species Task Force.  Reclamation is also an active participant in the Western Regional Panel for Aquatic Nuisances Species and assisted in the development of the Columbia River Basin Rapid Response Plan.  Reclamation has held numerous training sessions, and hosted a Western Invasive Mussel Management Workshop in May, 2009.  Further information has also been posted on Reclamation’s mussel website


In conclusion, USGS science has made significant advances to understand both the biology and the impacts of Asian carps on river systems.  This information has proven critical for our partners as they develop prevention and control efforts.  However, there is still much to learn as the Asian carps have the potential to enter new ecosystems.  USGS is committed to continuing our ongoing efforts and to assisting in new efforts, aimed at developing control methods.  We look forward to continuing our collaborative efforts with our local, State, and Federal partners. 

Thank you, Chairwoman Stabenow, for the opportunity to submit this testimony on USGS research to address the expansion of Asian carps in U.S. waters.  I will be pleased to answer questions you and other Members of the Subcommittee might have.




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