Weather Forecasting Invader of the Illinois River
BY CORY ANDERSON, CARTERVILLE FWCO – WILMINGTON, IL SUBSTATION
The main goal of the Carterville Fish and Wildlife Conservation Office (FWCO) Wilmington substation is monitoring and preventing upstream dispersal of Asian carp in the Illinois Waterway. In order to achieve this goal, many hours are spent electrofishing, gillnetting, and conducting sonar scans of the Des Plaines River, Illinois River, and Chicago Area Waterway System (CAWS). Despite extensive electrofishing effort in the CAWS, no Asian carp have been captured above the electric dispersal barrier since 2010. Instead, the result of this effort has been the capture of other introduced fish species such as Round Goby and the Oriental Weather Loach.
Oriental Weather Loach also called the Pond Loach or Weather Fish, are a popular aquarium fish imported from East Asia that have become an invasive species in our waterways. They have been reported in water bodies across the United States (US), including the Chicago Sanitary and Ship Canal and the CAWS. The Oriental Weather Loach is named for their supposed ability to predict the weather. These fish respond to changes in barometric pressure by swimming frantically and generally becoming more active. The actual accuracy of Oriental Weather Loach to predict incoming storms has not been evaluated.
The native habitat of the Weather Loach is in slow moving waters of the Tugur and Amur River basins of East Asia. Their range is from Siberia to northern Vietnam, and also includes Japan. This species is well adapted to survive in river conditions with slow flows and silt substrates like those found in many United States rivers that have been modified by dams. Oriental Weather Loach are bottom feeders with diets consisting of benthic aquatic insects and detritus. They are able to tolerate extreme water conditions or poor habitat quality and are even capable of using their intestine as a supplementary breathing organ in order to live in low oxygen conditions. This adaptation also allows them to burrow in sediment to escape predation and survive short periods of drought.
The widespread introductions and broad ecological niche of Oriental Weather Loach has led to breeding populations being established in several basins throughout the continental US and Hawaii. Populations in California, Michigan, and Louisiana were introduced as a result of fish escaping from Goldfish farms and other aquaculture facilities. Hawaii populations are thought to have come from immigrants introducing the fish as a food source. Populations in other parts of the US, like the population in the Chicago Sanitary and Ship Canal and upstream pools of the Illinois River, are likely a result of aquarium releases.
As with any aquatic nuisance species there are some negative effects of expanding populations of Oriental Weather Loach. The main concern is that increased Weather Loach abundance can lead to a decrease in benthic macro-invertebrates. Since macro-invertebrates are the primary food source for many juvenile game fish species and other native fish an increasing population of Weather Loach would mean more competition for macro-invertebrate prey. This competition, coupled with the hardiness of the Oriental Weather Loach to surviving in poor water quality, like that of the Chicago Area Waterway System, may lead to expanding populations and yet another aquatic nuisance species threatening US waterways.