Effects of alternative harvest regulations on Smallmouth Bass angler harvest in Missouri River reservoirs

ABSTRACT Objective Smallmouth Bass Micropterus dolomieu is an important sport fish in parts of the United States. Although voluntary angler catch and release is common in many Largemouth Bass Micropterus nigricans fisheries, Smallmouth Bass harvest may be higher in the northern Midwest. Our objectives were to evaluate temporal angler catch and harvest patterns and the potential effects of alternative bag and length limits for managing populations in Missouri River reservoirs, South Dakota. Methods We used angler use and harvest surveys and the fisheries analysis and modeling simulator (FAMS) to evaluate temporal angler catch and harvest patterns and the potential effects of alternative bag and length limits for managing populations in Missouri River reservoirs, South Dakota. Results The anglers that were targeting Smallmouth Bass had higher probabilities of catching, harvesting, and releasing Smallmouth Bass than the other anglers did. The probability of an angler catching and releasing a Smallmouth Bass increased from May 1 to September 1, whereas for anglers that caught a bass, angler catch, harvest, and release rates decreased with Julian day. Bag limits ≥3 fish/d resulted in small reductions in harvest, whereas bag limits 3 bass/d reduced harvest by 30–66%. Regulation modeling predicted that minimum length limits reduced harvest, increased proportional size distribution of preferred length, and protected spawning potential more than protected slot limits. However, angler use and harvest surveys projected that protected slot limits could reduce current angler harvest by 50–88%. The 457-mm minimum length limit increased Smallmouth Bass abundance, spawning potential ratio, and size structure more than 381- and 305-mm limits. In comparison, 356–457-mm and 305–508-mm protected slot limits allowed the most angler harvest but had little effect on spawning potential ratio beyond that of no size regulation. Conclusions Unlike many southern Smallmouth Bass populations, we found that anglers in Missouri River reservoirs readily harvest Smallmouth Bass and that more conservative bag limits and length limits could reduce harvest and increase abundance, spawning potential ratio, and size structure.