à£à£Ö±²¥Ðã

New research from South à£à£Ö±²¥Ðã State University's Department of Natural Resource Management examines how different states are stopping the spread of invasive carp. 

In April, the federal government signaled that it would provide additional funding to help the U.S. Army Corps of Engineers complete enhanced fortifications to prevent invasive carp from entering the Great Lakes through Lake Michigan.

The cost of the project — estimated at $1.2 billion — underlines the severity of the invasive carp problem in the United States. Invasive carp, also known as Asian carp, were brought to the U.S. in the 1970s to clean commercial fishponds. Flooding allowed the fish to escape, and they have slowly spread to most major waterways in the Midwest, causing immense ecological harm at every turn.

South à£à£Ö±²¥Ðã State University's Department of Natural Resource Management is leading research efforts on invasive carp in South à£à£Ö±²¥Ðã and parts of the Missouri River basin. Led by assistant professor Alison Coulter, graduate research assistant Hannah Mulligan and other faculty members, their research is focused on understanding the ramifications of invasive carp and ways to prevent them from spreading into new waterways.

Recently, Mulligan and Coulter investigating the different ways states and other countries are acting to prevent the spread of aquatic invasive species via the live baitfish trade. With this information, they also provided recommendations for what can be done with limited resources to slow the spread. The live baitfish trade, with an estimated industry size of $1.56 billion in the U.S., is one of the major pathways in which aquatic invasive species, like invasive carp, spread.

When invasive carp become entrenched in a waterway, they become nearly impossible to remove. That's why Mulligan suggests that investing in preventative actions should be prioritized.

"Prevention is emphasized as the most cost-effective way to limit human-mediated introductions and negative impacts of invasive species, but preventative actions are often implemented in a spatially and temporally imperfect manner," Mulligan said. "We reviewed the current knowledge of preventative actions including regulations, education and inspections."

The primary issue is that it is very difficult to tell the difference between different types of fish when they are small. Young invasive carp can accidentally, and often unknowingly, be used as bait.

"The live baitfish trade has the potential to spread invasive species beyond their current range and presents a major economic, ecological and social threat," Mulligan said. "We recommend an approach that capitalizes on interconnections and feedbacks among preventative actions when resources are limited, which should result in a synergistic outcome that optimizes resources within and among regions."

Mulligan suggests that bait disposal stations at lake or river access sites may encourage anglers to dispose of bait properly, rather than dumping bait into waterbodies. While dumping bait is illegal in many states, anglers often do this unknowingly.

"The risk is the transportation and subsequent release of bait that did not originate from the original waterbody," Mulligan said. "It is legal to release baitfish in the same waterbody you caught them in, but it is not legal to release baitfish you caught or bought from another area. The risk is the release of baitfish that did not originate from the waterbody which can result in introductions of invasive carp, zebra mussels, pathogens and other aquatic invasive species."

As Mulligan notes, a bait disposal station could help this problem.

"Most anglers release baitfish because of the misconception that it provides an additional food source for sportfish species, because it is convenient to release rather than properly dispose of the live baitfish or because they morally oppose euthanizing the baitfish," Mulligan added.

In terms of the live baitfish trade, Mulligan suggests focusing inspection efforts on bait wholesalers, especially when there is limited funding available, as there are fewer wholesalers than bait retailers or anglers. She also notes that additional harvest restrictions on baitfish or online aquatic invasive species training could be beneficial for jurisdictions that do not have a large number of wholesalers or bait retailers.

"Focusing on wholesalers as a critical control point for the identification and mitigation of invasive species would subsequently reduce introduction risk later in the pathway, which is comparable to border surveillance at or near ports of entry," Mulligan said. "Screening baitfish for pathogens and invasive species prior to sale at a bait retailer may also be more time and cost effective than relying on anglers to identify invasive species within their purchased baitfish."

Funding is often the greatest barrier to invasive species management, but, as Mulligan notes, that may be overcome through increased information and resource sharing among states and regions. She points to regional management panels, where information and resources are shared over an entire region or river basin, as a model for this strategy. Further, she noted unpublished research, such as management reports, state angler surveys, and outreach materials on aquatic invasive species, could become more accessible.

"Prioritizing the live baitfish trade in management and identifying, implementing and sharing cost-effective approaches should lead to greater spatial coverage and impact to reduce aquatic invasive species spread via the live baitfish trade," Mulligan added.

Although individual states must leverage limited resources to focus on cost-effective approaches that prevent aquatic invasive species introductions within their individual jurisdiction, communication and coordination across jurisdictions is still needed to successfully reduce the risk among regions, Mulligan notes.

The full study, titled was published in the academic journal BioScience.

Funding for this research was provided by the U.S. Fish and Wildlife Service, South à£à£Ö±²¥Ðã Game, Fish and Parks, SDSU's Graduate School and the South à£à£Ö±²¥Ðã Agricultural Experiment Station.