Oxygen Supply Threatens Lake Trout Fishery in Maine’s Lake Auburn, No Threat to Drinking Water
The Maine Department of Inland Fisheries and Wildlife is investigating a fish kill of considerable importance on Lake Auburn. It involves lake trout (togue) and some suckers and other deep dwelling lake fish.
The fish kill began late last week and is continuing according to regional fisheries biologist Francis Brautigam. The reason for it is a lack of dissolved oxygen in the cooler, deeper parts of the lake. The fish, in effect, suffocate to death.
The Auburn Water District and Lewiston Water Division are cooperating with biologists from the Department of Inland Fisheries and Wildlife to monitor increased algae activity on Lake Auburn. Lab personnel recently noticed dead fish and performed increased water quality tests showing the dissolved oxygen was low in the deeper lake water. These results were shared with the Department of Inland Fisheries and Wildlife who completed additional sampling confirming depleted dissolved oxygen levels in the deeper elevations of the Lake. The low oxygen levels, combined with elevated water temperatures, are stressing the lake trout population. The IF&W biologists speculate heavy prolonged spring rains combined with the long hot summer weather stimulated natural algae growth which ultimately led to the depletion of oxygen. It is expected that the low oxygen levels and warm water temperatures will result in the death of some of the lake trout, which are a species that prefer cold, deep water.
Public drinking water quality has not been affected. The intake pipe for Lewiston and Auburn is located in shallow water having normal oxygen readings. It is continuously monitored 24 hours per day. No public health threats have been identified and Lewiston-Auburn works closely with officials at the Maine Drinking Water Program.
The death of lake trout is particularly troubling says Francis Brautigam, regional biologist for MDIFW. “This could significantly impact what has been a historically good lake trout fishery in southern Maine,” says Brautigam. Historically renowned for the high quality of its water and its fisheries, Lake Auburn was added to the Maine Department of Environmental Protection’s watch list last year as a result of recent deteriorating water quality and a fall algae bloom.
The latest algae bloom was first noted last month. Freshwater algae blooms are caused by increased nutrients and grow quickly, but are short-lived and the resulting decay consumes significant quantities of dissolved oxygen, robbing it from other plants and animals, including cold-water fish that are high oxygen-dependent.
The Auburn Water District, the Lewiston Water Division, the Maine Department of Inland Fisheries and Wildlife, and the Maine Department of Environmental Protection continue to work closely together in monitoring the lake to insure the safety of all who depend upon as their drinking water source.
