Lake trout appeared to have been moderately abundant in Duncan Lake in 2013. Although most of the lake trout taken in this assessment were small, a few larger fish were present. Natural reproduction alone appeared to have been capable of supporting a good lake trout population in this lake, since the lake had not been stocked since 1988. The 2013 lake trout gill net catch was similar to past catches observed in this lake. The mean weight was low, mainly due to the presence of fairly high numbers of smaller fish from a strong 2010 year class. A total of six year classes, all naturally produced, contributed to the 2013 lake trout catch. Growth of young lake trout had been about average for a lake in this area; fish reached a mean length of 10.0 inches by the end of their third year.
Forage for lake trout was provided by fairly high numbers of cisco. The cisco gill net catch was within the normal range for a lake of this type, and was similar to past catches seen in this lake. Although no cisco were aged, their size distribution suggested that at least two strong year classes were present. Additional forage was probably provided by rainbow smelt, which have been present in Duncan Lake for many years, but which have not always been taken in standard assessment gear.
Only a single smallmouth bass was taken in the 2013 assessment; however, similarly low catches have been observed in the past in this lake. Gill net catches are usually not a good indicator of smallmouth bass abundance. White sucker abundance seemed to have been low, yellow perch were present in average numbers for a lake of this class, and small green sunfish seemed to have been abundant in 2013.