Muskellunge Management: Fifty Years of Cooperation Among Anglers, Scientists, and Fisheries Biologists
Spring Flow Variability Associated with Muskellunge Recruitment on the Upper James River, Virginia [Abstract]
Daniel B. Goetz and Scott M. Smith
Muskellunge Esox masquinongy fingerlings were stocked in the upper James River during most years from 1972 to 2010. Significant increases in Muskellunge relative abundance were detected beginning in the early 2000s. Annual increases in age-0 Muskellunge catch per unit effort (CPUE), even during years with no stocking, led biologists to cancel the stocking program in 2010. Since then, Muskellunge CPUE has continued to increase exponentially, while age-0 CPUE has been variable. We analyzed Muskellunge CPUE, water quality, and river discharge data during 2000 to present for the upper James River in an effort to explain increases in Muskellunge. We used a combination of regression techniques to identify abiotic variables associated with Muskellunge year-class strength. Age-0 CPUE increased significantly with fluctuation in spring discharge (range of mean monthly flows from March to June, ft3/s). Catch-curve residuals for respective year-classes also increased significantly with fluctuation in spring discharge. Fall age-0 CPUE decreased significantly with slope of mean monthly flows in spring, suggesting that declining spring flows were important for Muskellunge recruitment. Age-0 CPUE increased significantly with conductivity, suggesting that productivity during declining spring flow regimes is greater than in years with stable or increasing spring flow regimes, which may further increase age-0 survival. Years with the highest flows in March, followed by declines through June, produced the strongest Muskellunge year-classes on the upper James River.