While boiled Louisiana crawfish are catching on across the nation due in part to a Hurricane Katrina diaspora of New Orleanian foodies and simply the tastiness of the critters, live crawfish might be crawling around the United States and Canada more than one might think. According to a study presented this week in Portland at the national meeting of the Ecological Society of America, our Louisiana red-swamp crawfish could be competing against crawfish species in other parts of the country.
The Oregon State University study, which the university promoted in a recent news release, found that one out of four teachers surveyed in the U.S. and Canada, who use live animals as part of their science classes, release the animals into the wild after they are done with them. Louisiana crawfish often are used around the country because many local “crayfish” have a higher mortality rate. There are more than 350 different crawfish species in the United States alone.
Sam Chan, an Oregon State University invasive species expert and a principal investigator on the study, says Louisiana crawfish are “quite hardy” and therefore can survive more easily in a classroom setting. At the same time, though, that strong constitution also makes it easier for them to survive outside of the classroom when later released into a non-native habitat.
The study shows that classrooms are one way that organisms can enter non-native environments and Chan asks that teachers and suppliers must learn the consequences of moving animals and plants from habitat to habitat.
In terms of the teachers that reported releasing the organisms, about 10.5 percent said they had participated in planned release programs, wherein the animal often is released in a less intrusive area. Teachers were almost evenly split on whether they would kill animals used in classroom activities.
Surveyed teachers noted 904 different non-native plants and animals species used in their classrooms, but the single animal released most often was crawfish, often from Louisiana and typically used in 3rd to 5th grade classrooms across the country, Chan said.
Chan says some 4th graders recommended a few alternatives to releasing the mudbugs into non-native habitats.
“Maybe we can eat them?” Chan says was one of their thoughts.
Released non-native Louisiana red-swamp crawfish, which make up about 80 percent of our local market, can push native crawfish out of their burrows and “can become very reproductive” in non-native environments and also will eat native plants to survive, said Chan, who also is a Sea Grant Extension specialist and former chair of the Oregon Invasive Species Council.
While surveyed teachers provided Chan and his colleagues with the names of about 10,000 different organisms, the list was dwindled down to the 904 species after the scientists realized that many teachers often used a variety of common names to described the same species. For example, for crawfish, teachers often listed them as crayfish, crawdads, or, crawfish.
The Oregon State University study surveyed nearly 2,000 teachers in eight states — Florida, New York, Indiana, Illinois, Oregon, Washington, California and Connecticut — and the Canadian provinces of British Columbia and Ontario. It also included focus groups and interviews with teachers, curriculum specialists and the companies that supply live animals.
In addition to Louisiana crawfish, some other known or potential aquatic invasive species that teachers noted were elodea (commonly called waterweeds), frogs, boa constrictors, goldfish, mosquitofish, red-eared slider turtles and other aquatic plants and snails.
Crawfish as a teaching tool has caught on largely through FOSS, or Full Option Science System, which is used by many school districts and encourages crawfish as a teaching tool for 3rd to 5th grades to study the animals’ behavior and habitat, Chan said.
“You can’t really have students learn about habitats and behavior in a virtual context because you can’t really observe them,” said Chan, noting why studying live animals is important to a child's education.
He said that about 25 percent of school districts across the country receive crawfish and often each classroom receives about 12 to 24 crawfish per year.
“So you probably are looking at a pretty substantial number,” he said. “I don’t know how many schools districts there are in the country, but you take 25 percent of that and multiply that by 12 or 24 and that’s a lot.”
Funded by the National Oceanic and Atmospheric Administration, the Oregon State University study found that teachers often don’t know what to do with the animals after using them as science exhibits in their classrooms. About 50 percent of the animals used by teachers came from pet stores or aquariums; the others from supply houses, according to the study.
In addition to the 4th graders’ suggested method of eating crawfish, Chan suggests that other more eco-friendly options could include classrooms only using species native to the local environment. Another option is giving the non-native species to a local pet store, veterinarians, or simply returning them to the original supplier, Chan said.
He says 4th graders also suggested that they could take care of them at home over the summers and then returned to the schools in the fall.
Invasive crawfish reeking havoc on native crawfish species is nothing new.
American signal crawfish are invasive in Europe and have carried parasites that infect the local populations. The signal crawfish also eat more than the native white-clawed cousins and thereby deplete the native food source. Rusty crawfish, native to the Ohio River basin, have invaded many lakes and streams in Minnesota, Wisconsin, Michigan, Illinois, Ontario and portions of 17 other states causing a variety of ecological problems.