By ANI ESCOBAR and JIM PAGE
At first glance, the fish looks unassuming. Its chin barbels remind you of a catfish. Its spots suggest something tropical. Usually less than a foot long, this mild aquarium pet has a face of innocence.
However, the Oriental weather loach – documented for the first time in the wild in Georgia last month – could spell trouble for aquatic ecosystems across the state.
Also called the dojo or pond loach, this Asian species and popular aquarium fish has been introduced to Europe, Australia and at least 13 states in the U.S., including Alabama and Tennessee.
While sampling for Altamaha shiners in early November, University of Georgia researchers were surprised to find several loaches in McNutt Creek, a tributary to the Middle Oconee River near Athens. After identifying the mystery catch, they worked with DNR to explore the fish’s status in the creek.
As part of that cooperative plan, the team did more sampling, collecting at least 15 more loaches. The catch ramped up concerns about impacts the species might have if it is established and reproducing.
UGA crew searches for weather loaches in McNutt Creek near Athens (Andrew Davis Tucker/UGA)
SIZING UP THE IMPACT
Two questions are triggered when biologists first find a non-native fish in the wild: How is it going to act in the system and how widely is it distributed? If the weather loach is widening its range and could negatively affect native fish, it will be added to Georgia’s growing list of aquatic nuisance species.
Little is known so far about how the species interacts with and affects native ecosystems. But studies asking these questions have shown that weather loaches eat native insects and could influence nutrient dynamics, which can skew the natural food web and alter how the ecosystem functions.
Biologists are working to determine what the fish is eating in McNutt Creek, what kind of habitat it’s using and, perhaps most importantly, if it is reproducing. An established, reproducing weather loach population can be invasive – meaning it can cause significant ecological harm in Georgia waters.
Altamaha shiner (Nate Tessler)
ALTAMAHA SHINER AT RISK?
What’s at stake? Plenty.
With about 265 native freshwater species, Georgia ranks as the nation’s third-most diverse state for fish. Non-native fish introduced into streams, ponds and reservoirs can put native species at risk.
While declines in aquatic species are sometimes caused by a single factor, more often it is a combination. Populations of the state-protected Altamaha shiner – which is found in McNutt Creek – are shrinking primarily because of habitat degradation, fragmentation and loss. But adding an invasive Competitor can compound that decline.
While the Oriental weather loach likely won’t prey on adult Altamaha shiners, it could compete with them for food, eat their eggs and young, or create other stresses in the ecosystem.
For now, distribution of weather loaches in McNutt Creek and its tributaries isn’t known. Biologists are trying to eradicate the fish, hoping to prevent any fallout and any spread into the nearby Oconee River.
Oriental weather loach (Bryson Hilburn)
WEATHER LOACH/AT A GLANCE
- Officially: Misgurnus anguillicaudatus
- Appearance: Eel-like, brown with greenish gray-brown marble markings, small mouth surrounded by barbels. Grows up to a foot long.
- Survivor: Tolerates marginal habitat and extreme conditions. Can survive in oxygen-poor water and bury itself in mud and breathe air outside of water to survive droughts.
- The name: “Weather” refers to the fish becoming more active as the barometric pressure changes. Loaches are freshwater, bottom-dwelling fish native to Eurasia and north Africa.
– U.S. Geological Survey
HOW YOU CAN HELP
The discovery of Oriental weather loach is only Georgia’s latest instance of a non-native fish being introduced outside its native range. From flathead catfish in the Satilla River to northern snakeheads in Gwinnett County and red shiners in the Chattahoochee, Ocmulgee and Coosa watersheds, many species have been moved across watersheds – and even oceans – to systems where they aren’t native.
Though some introductions are from natural events such as hurricanes or floods, most involve people. And these introductions often come with a price.
Trying to remove or control invasives can be costly, time-intensive and daunting. The best way to minimize the impact is to prevent the introduction.
Weather loaches are probably in McNutt Creek because an aquarium owner who no longer wanted the fish released one or more there. Releasing non-native species into the wild in Georgia is illegal. People who have a non-native fish they don’t want should contact the store where they bought it or call DNR.
To prevent unintentionally introducing animals, plants, diseases and other “hitchhikers,” thoroughly wash and dry boats, waders, wading boots and other equipment when moving between waterbodies.
Remember, the choices we make and actions we take today may have an impact beyond tomorrow.
More on aquatic nuisance species and invasive animals and plants in Georgia.
Ani Escobar is a DNR aquatic biologist focused on conservation in the Coosa River Basin. Jim Page is a DNR senior fisheries biologist and aquatic nuisance species coordinator for Georgia.
Cover photo: Oriental weather loach from McNutt Creek (Andrew Davis Tucker/UGA)