Muskellunge Management: Fifty Years of Cooperation Among Anglers, Scientists, and Fisheries Biologists

Tiger Muskellunge Growth, Condition, Diet, and Effect on Northern Pikeminnow at Curlew Lake, Washington

Marcus J. Divens, William P. Baker, Bruce D. Bolding, and Randall S. Osborne


Abstract.—Tiger muskellunge (Muskellunge Esox masquinongy × Northern Pike E. lucius) growth, condition, and diet, as well as the effect of stocking on Northern Pikeminnow Ptychocheilus oregonensis, were studied at Curlew Lake, Washington from 2001 to 2006. Curlew Lake (373 ha) was stocked with tiger muskellunge beginning in 1998 to reduce an overabundant Northern Pikeminnow population and to create a unique trophy fishery. Historically, Curlew Lake had provided good fishing opportunity for stocked Rainbow Trout Oncorhynchus mykiss, as well as naturally reproducing Largemouth Bass Micropterus salmoides and Smallmouth Bass M. dolomieu. The quality of trout fishing, however, had declined throughout the 1990s, commensurate with anecdotal observations of increased numbers of Northern Pikeminnow in the sport catch. To monitor changes in species relative abundance, the lake was sampled annually in the fall with standardized boat electrofishing surveys. Additionally, the lake was sampled by boat electrofishing monthly, from spring through fall, to collect tiger muskellunge diet samples by gastric lavage. Rainbow Trout and Northern Pikeminnow were the most important prey species for tiger muskellunge in Curlew Lake while Largemouth Bass were a distant third. Diet varied seasonally, with Rainbow Trout being the most important prey during spring, while Northern Pikeminnow was most important in summer. Both Rainbow Trout and Northern Pikeminnow were important in the fall. The relative abundance of Northern Pikeminnow in Curlew Lake significantly declined over the duration of the study. The high proportion of Northern Pikeminnow observed in the tiger muskellunge diet analysis indicates that the reduction can be attributed to the added presence of tiger muskellunge to the community. Therefore, the goal of Northern Pikeminnow population reduction through tiger muskellunge introduction (biological control via predation) has been successful. Continued biannual monitoring of the fish community to assess Northern Pikeminnow abundance should provide the necessary data to refine future tiger muskellunge stocking rates in Curlew Lake.