Evaluation of a 16-Inch Minimum Length Limit for Smallmouth Bass in Pallette Lake, Wisconsin

Abstract

We evaluated a 16-in minimum length limit and two-fish daily bag limit for smallmouth bass Micropterus dolomieu in Pallette Lake, Wisconsin, from 1989 to 1996. Fish abundance, biomass, growth, survival, and angler harvest were compared with data from years when no length or bag limits were in force. Angler harvest and fishing effort were monitored by a complete mandatory creel census. Following the regulation changes, fishing effort increased by 62% despite a 95% decline in smallmouth bass harvest. The number and biomass of smallmouth bass 12.0–15.9 in and 16.0 in and greater increased, whereas the number of fish 6.0–11.9 in declined. Annual survival rates of fish age 3 and older increased from 0.21 during the no-limit years to 0.60 during the length-limit years. Annual exploitation rates for fish 8 in and greater averaged 0.53 during the no-limit years and 0.10 during the length-limit years. Smallmouth bass growth rates did not change. During the no-limit years, 27% of the anglers harvested smallmouth bass compared with only 3% of anglers during the length-limit years. The bag limit reduced harvest during only 3 years by an average of 11% (3 fish/year). Anglers accepted the restrictive regulations well and were primarily concerned about catch rates of fish 16.0 in and greater. For managers wishing to increase angler interest and numbers of fish 16.0 in and greater, we recommend considering similar or even more restrictive regulations. However, a sharp reduction in the number of smallmouth bass above the minimum length limit should be expected.