AUTHORS: Todd Caspers, North Dakota Game and Fish Department
ABSTRACT: Devils Lake is one of North Dakota’s most important fisheries. White bass (Morone chrysops) were stocked in Devils Lake one time in 1971 to provide a sportfish that could tolerate the higher salinity levels at the time. White bass gained a foothold in the lake from that stocking and have reproduced naturally since that time. White bass are a secondary sportfish in the lake and most anglers do not target them. As such, little special attention has been devoted to studying the white bass population in Devils Lake. White bass recruitment in Devils Lake is sporadic and “bass booms” can occur when a strong year-class is produced. The 2015 year-class was likely the strongest to date and produced a “bass boom”. However, year-classes for several years before and after 2015 were weak. This situation presented the opportunity to use length frequency information to track the 2015 year-class through time to provide an estimate of growth and mortality. Growth was indexed using mode length and growth was rapid for the first several years, with mode length reaching 310 mm by age 3. The initial mortality estimate for ages 3 through 5 produced a total annual mortality rate of 12%, which is low and indicates that neither natural nor fishing mortality is excessive. Subsequent mortality estimation was complicated by a disease outbreak in 2021, but total annual mortality for ages 3 through 8 was estimated to be 35%.
