New methods of DNA screening are allowing for detection of invasive fish species in the bait trade and outreach to anglers may help to stop the spread of invasive species into Ohio and the Great Lakes region.
An invasive species is one that has moved into an area it is not native to and damages the environment and organisms that are already established. Invasive species can drive native species out and the damage done can often be economic as well as environmental. Some Aquatic Invasive Species (AIS) already have a significant presence in Ohio, such as Zebra Mussel, White Perch, and Round Goby. There are two species of Asian Carp, Silver Carp and Bighead Carp, that are of particular concern to Ohio wildlife managers. While not yet established in the Great Lakes, Asian Carp are abundant in the Mississippi and Illinois, through which they pose a serious threat of invasion (Nathan et al. 2015). These voracious carp have the potential to decimate an ecosystem, and the Silver Carp can even jump out of the water and strike fisherman (http://ohiodnr.gov/asiancarp).
Silver Carp jumping out of the water in the Illinois River
Photo by Nerissa Michaels, Illinois Natural History Survey
Invasive species can be introduced to an ecosystem in a number of different ways. Ballast water from ships, the exotic pet trade, and even habitat managers purposefully introducing a non-native species are sources of AIS. One invasive pathway many people may inadvertently contribute to, is the bait trade. When anglers buy live bait it may contain other invasive species that can be released into the ecosystem. White Perch, Tubenose Goby, and Ghost Shiner are some examples of established non-native fish in the Great Lakes that are used as baitfish. Baitfish are sometimes sourced from other regions of the country where other AIS are and may result in movement of AIS to new parts of the country (Nathan et al. 2015). To help track the threat of AIS, DNA test have been conducted to track the prevalence of infected baitfish stocks across the region.
Instead of visually searching every bait store for individual organisms, Environmental DNA Surveillance can be used to passively determine if a baitfish supply is infected with AIS. Environmental DNA (eDNA) Surveillance is a method where small strands of DNA are extracted from a water sample, in this case water taken from bait stores. These bits of DNA are not pulled directly from an organism, but rather have been excreted or left behind in the water. These small samples are amplified in a lab using a process called Polymerase Chain Reaction. The amplified strands are then checked against a database of known samples to identify what species of fish were present in the water sampled (Nathan et al. 2015, Mahon et al. 2014).
One study looked at 576 eDNA samples taken from 525 bait shops across all 8 states bordering the Great Lakes. AIS DNA was detected 27 times, including three instances of Silver Carp along the coast of Lake Erie in Ohio (Nathan et al. 2015). Similar studies have also detected White Perch, another species whose sale and possession is banned in a number of Great Lakes states (Mahon et al. 2014). Closing this pathway of invasion poses some challenges though.
Ohio Department of Natural Resources, Division of Wildlife. QuickID Features for Baitfish [Digital image from Powerpoint presentation]. Retrieved from http://ohiodnr.gov/Portals/0/pdfs/invasives/Pub%205487-D_Baitfish%20ID_WEB.pdf
Bait sellers are very often unaware of the species of baitfish they are selling, let alone whether it is invasive or not. And anglers often don’t know that throwing unused bait fish in the trash and not the water is the preferred method of disposal (Nathan et al. 2014).
Preventing the spread of AIS through baitfish is further complicated since many states have different laws as to what constitutes legal baitfish. The issue crosses international borders as well. The Threespine Stickleback is listed as an invasive but is allowed in Ontario (Nathan et al. 2014). Efforts are underway to inform fisherman and bait sellers of the potential for introduction of AIS into the Great Lakes through baitfish (http://ohiodnr.gov/invasive-species/aquatic-invasives/bait-trade). Any sightings of Asian Carp in Ohio can be reported at http://ohiodnr.gov/asiancarp. Further outreach to anglers, consolidation of bait laws and potential regulation of the bait industry may be needed to seal up another avenue through which AIS can enter and devastate ecosystems.
Text Citations
Mahon, A. R., Nathan, L. R., & Jerde, C. L. (September 01, 2014). Meta-genomic surveillance of invasive species in the bait trade. Conservation Genetics Resources, 6, 3, 563-567. https://doi-org.proxy.lib.ohio-state.edu/10.1007/s12686-014-0213-9
Nathan, L. R., Mahon, A. R., Jerde, C. L., & McVeigh, M. (January 01, 2014). An assessment of angler education and bait trade regulations to prevent invasive species introductions in the Laurentian Great Lakes. Management of Biological Invasions, 5, 4, 319-326. doi: http://dx.doi.org/10.3391/mbi.2014.5.4.02
Nathan, L. R., Jerde, C. L., Budny, M. L., & Mahon, A. R. (April 01, 2015). The use of environmental DNA in invasive species surveillance of the Great Lakes commercial bait trade. Conservation Biology, 29, 2, 430-439. doi:10.1111/cobi.12381
http://ohiodnr.gov/invasive-species/aquatic-invasives/bait-trade
http://ohiodnr.gov/asiancarp