Jeff Boxrucker, Oklahoma Fishery Research Laboratory, Oklahoma Department of Wildlife Conservation, 500 E. Constellation, Norman, OK 73072

Abstract. The objective of this presentation is to detail the changes in the white crappie Pomoxis annularis population structure on Ft. Supply Reservoir prior to, during, and following removal of restrictive harvest regulations. Annual fall trap-net samples have been collected since 1983. Spring creel data have been collected since 1987. The 1983-1989 trap-net samples indicated that the crappie population was dominated by fast-growing age-1 and age-2 individuals. The percentage of age-3 and older crappie in the population never exceeded 10% during this time period. The fishery was supported by a single year class (age 2). Mortality rates of age-2 crappie averaged 73%. Tagging studies in 1987 and 1988 indicated that annual angler exploitation was 40%.

A 255-mm minimum length limit with a 15-fish daily creel regulation was imposed on January 1, 1990. Trap-net catch rates of crappie >200 mm and >250 mm increased following the restrictive harvest regulations. Percentage of crappie age-3 and older exceeded 10% 4 of the 6 years that the regulation was in effect. Mortality rates of age-2 crappie averaged 53% from 1990-1995. The improvements in crappie population structure evidenced by the trap-net samples were not reflected in the creel data. Fishing pressure steadily declined. Angler catch rates improved during the length limit but harvest rates declined to 0.4 fish/h and remained fairly stable. Angler acceptance of the regulation was poor in spite of numerous public forums and articles in the local media. The restrictive harvest regulations were removed on January 1, 1996.

Fishing pressure has not improved since the restrictive regulation was removed. Crappie harvest estimates from spring 1996 were twice the spring 1995 estimates. The increase in harvest was due to harvest of crappie between 200 and 250 mm previously protected by the length limit. The increase in harvest was reflected in a 50% decline in trap-net catches in fall 1996. However, local anglers are now satisfied with the fishery.