Anglers note decline in brown trout fishery likely due to common merganser predation

Fisheries staff from the New York State Department of Environmental Conservation (DEC) will hold a public meeting from 7:00 pm to 9:00 pm on January 11, 2016 in the Caledonia-Mumford High School auditorium, 99 North Street in Caledonia, Livingston County, to discuss the decline in trout fishing quality of Spring and Oatka Creeks.

DEC received many reports of poor fishing in Oatka and Spring Creeks in Monroe and Livingston Counties during the springs of 2014 and 2015. These two streams are popular with anglers and have traditionally provided an excellent fishery of wild brown trout.

As a result of these calls, staff surveyed a section of Spring Creek called Veteran's section, in late November 2014 and 2015, and Oatka Creek near Union Street in late November 2015. Staff compared the new survey results to previous results from the Veteran's section in 2001 and Oatka Creek in 2003. In both instances, the abundance of brown trout dropped significantly in 2014 and 2015, and the number and percentage of yearlings should have been higher.

The population decline is likely due to common merganser predation on the trout. The common merganser is a frequent winter visitant on the Great Lakes and the larger lakes of interior New York. It is a freshwater fish eating bird and in waters with trout or salmon, mergansers feed on a high proportion of these game fish. One report states that trout make up 84% of the total common merganser diet and the remainder consisted of other fish species.

The winters of 2013-2014 and 2014-15 were the first time mergansers had been seen on Spring Creek at the Caledonia Fish Hatchery for at least 30 years. Those winters were very cold and many large water bodies that normally don't freeze completely over, froze over completely. When these large bodies of water froze over, the common mergansers moved to find available open water on which to feed. The spring-fed sections of Spring and Oatka Creeks were tempting locations for these birds to move to during the severe winter months of 2013-2014 and 2014-2015. These sections are slow to freeze over because of the relatively warmer temperatures of the water due to the influx of groundwater from the springs.

DEC will consider constructing trout escape cover habitat enhancements in Spring Creek on the Caledonia Fish Hatchery property. A Vermont study showed that escape cover enhancement in a stream reduced merganser predation and improved the brown trout population. Spring Creek and Oatka Creeks are very productive streams and it is likely that the wild brown trout populations should recover if merganser predation is reduced.