Voluntary release of fish can play an important role in the management of recreational fisheries. I investigated how the release rate, defined as the proportion of all fish caught that are released, may be affected by minimum length regulations and changes in angler behavior over time for walleye Stizostedion vitreum and muskellunge Esox masquinongy fisheries in northern Wisconsin. Release rates estimated from creel surveys were compared among years over a 10‐year period and between different minimum length regulations. The release rate for walleyes varied significantly between different minimum length regulations but did not vary among years. The muskellunge release rate increased significantly over time but did not vary between different minimum length regulations. The magnitude of the difference in release rate between the two substantially different length regulations in the walleye fishery (9.0%) was similar to the increase in the release rate over time in the muskellunge fishery (7.5%). The similarity in magnitude of effects of both regulatory actions and angler behavior on release rate demonstrates that the effects of voluntary release can play as large a role in the management of a fishery as regulations such as minimum length limits and suggests the importance of considering the effects of voluntary release in fisheries management decisions.