Sniffing Out Zebra Mussels
Originally published on The Wildlife Society (5.14.13).
The Minnesota Department of Natural Resources (DNR) announced last week that it will start using dogs to assist inspections of recreational watercraft for zebra mussels — a non-native species that has invaded 65 of the state’s lakes and could spread rapidly if preventative measures aren’t taken, putting native mussels and other aquatic life at risk. This makes Minnesota the second U.S. state to implement a program that enlists dogs to sniff out the invasive species.
About six years ago, California became the first state to use specially trained sniffer dogs to inspect watercraft for zebra mussels. Dogs’ noses can be far more efficient than the human eye at detecting the tiny mussels, which can be less than two inches long. Earlier this year, experienced K-9 officers with the California Department of Fish and Wildlife (CDFW) began training Minnesota DNR staff to use dogs, whose strong sense of smell has proven invaluable for tracking invasive and endangered species. CDFW officers look for breeds and individuals in shelters that are healthy, sociable, and have a strong search drive.
Lynette Shimek, the K-9 unit coordinator and dog handler with the CDFW’s Law Enforcement Division in Sacramento, taught two Minnesota DNR officials how to acclimate a dog to a new target odor — a skill dogs can learn in only five to 20 minutes. Using fresh zebra mussels, Shimek trains the dogs to recognize the odor and to alert the trainer that the odor has been detected. “As soon as the dog sniffs the odor out of curiosity, we raise the source up slightly, the dog sits, and we give them a reward,” Shimek said. Watch Minnesota DNR conservation officers demonstrate a boat search using their newly trained dogs, below.
Once trained, the dogs must then learn to locate the odor under different environmental conditions — a skill that requires additional weeks of training. Environmental conditions include the presence of other odors in the search area; variations in weather, temperature, wind, and humidity; noises and other distractions; unstable footing; and handler distractions.
In California, the program has not only succeeded in detecting infested boats, but it has also streamlined the inspection process. Whereas a person takes 10 to 20 minutes to properly check a single boat, a dog can do the job in two to three minutes. Boat owners are also more willing to submit to inspections when dogs are involved. “They are fascinated by watching the dog search, and by the relationship between the handler and the dog,” Shimek said.
But for all of the benefits dogs confer, they have limitations. The summer months, when inspections take place, tend to be stifling. The dogs can only work a short time before they get overheated and have to take a break. “Checking 300 boats a day isn’t possible,” Shimek said. “We look for boats with moisture on them or boats that are coming from areas where there has been an infestation” of zebra mussels.
It’s unclear if any studies assessing the efficacy of dogs as an invasive species management tool will be conducted, but anecdotal evidence suggests they are effective. “I think it’s a really good tool to have,” said Dan Swanson, a Minnesota DNR species biologist. There are currently three dogs in Minnesota’s new program and more may be added later if the program proves successful. Swanson is hopeful that the dogs will be used as soon as this week at lakes throughout the state.
Zebra mussels (Dreissena polymorpha) — a freshwater species native to Eastern Europe and Russia — were first brought to the U.S. in the ballast water of freighters that made their way to the Great Lakes through connecting waterways from the Atlantic Ocean. The mussels were first discovered in 1988 at Lake St. Clair in Canada, and in just two years they had spread to the Great Lakes and the Mississippi River. Now, zebra mussels are hitching their way across the U.S. on boats, barges, and other recreational watercraft, wreaking havoc on aquatic ecosystems along the way.
The filter-feeding mussels can impact natural food webs when present in high densities. They remove plankton, microorganisms, and other nutrients from the water, depriving zooplankton and larval fish of food and increasing competition for resources between native mollusk species and zebra mussels. The mussels also attach themselves to any solid surface within a body of water, often adhering to native mussels — including endangered Higgins eye mussels (Lampsilis higginsii) — and killing them. Nearly three-quarters of North America’s 297 native freshwater mussel species are endangered, according to the National Resources Conservation Center, and an estimated 35 species are already extinct.
Minnesota DNR conservation officers show how dogs will be used to sniff out zebra mussels. (Credit: Minnesota Department of Natural Resources)
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