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The effects of maximum, minimum, and slot length limits on the sizes and relative abundance of northern pike Esox lucius were evaluated in 22 Minnesota lakes. The regulations were implemented in 1989–1998 and lasted 9–15 years. As preregulation information was available back to the 1970s, the evaluation periods covered 21–37 years. Comparisons were made with reference populations from 47 ecologically similar lakes during the same extended period. Although the regulations did not achieve management objectives in every lake, the broader‐scale, statewide finding was that they improved the size structure of northern pike populations but produced no consistent trends in relative abundance. The improvements were detected against the backdrop of reference populations that initially appeared to have similar sizes and relative abundances. Maximum length limits protecting fish over 20, 22, and 24 in produced significant long‐term increases in the percentages of northern pike 24 in and longer and 30 in and longer compared with the reference populations. Lakes with 30‐in minimum length limits had increased percentages of northern pike 20 in and longer, but the improvements did not carry over to fish 30 in and longer. A mix of slot length limits produced results that are more difficult to interpret but generally improved size structure. A metaanalysis incorporating all of the length regulations indicated that the changes in northern pike size structure in regulated lakes were very large for an ecological experiment. Length limits protected large northern pike, with the expectation that lower yields were an acceptable trade‐off for producing larger fish for recreational fisheries. This study reveals the range and magnitude of responses we can reasonably expect from length limits as well as the substantial value of conserving large fish when the goal is improved population size structure.

The potential benefits of catch and release or protective size limits in recreational fisheries for walleye Stizostedion vitreum can only be realized if released fish survive. In this study, hooking mortality rates were determined for adult walleyes caught on leeches and artificial lures in two Minnesota ponds. The mortality of walleyes caught and released by anglers in Klawitter's Pond was 5%, though confidence intervals indicated that hooking mortality could have been as high as 23%. Mortality of walleyes caught on leeches (10%) was higher than mortality for walleyes caught on artificial lures (0%). An estimate of hooking mortality in Clubhouse Pond, unadjusted for natural mortality, was 16%. Walleyes caught on artificial lures were hooked primarily in the lips, whereas fish caught with leeches tended to be hooked more deeply in the throat and gut. Walleyes caught on leeches were smaller than those caught with artificial lures and were more likely to be males. Catch rates were similar for live and artificial baits but varied between the two ponds and 2 years of study. Low hooking mortality suggests that release of angler-caught walleyes has the potential to expand recreational fishing opportunities.

Northern pike (Esox lucius) is a popular sport fish in the United States and Canada that is currently managed for multiple angler uses. However, there has been increased concern over lower quality (i.e., smaller fish) northern pike populations. In 1997, the Esocid Technical Committee (ETC) of the North Central Division of the American Fisheries Society surveyed natural resource agencies about their northern pike management. In addition, a round‐table discussion on the quality of northern pike management was conducted in 1999. This paper is a summary of the ETC findings. In some cases, northern pike regulations have existed since the late 1800s, but most states and provinces did not use regulations until the 1950s or 1960s. Some agencies currently manage northern pike for angling quality (i.e., more large fish), others have few or no northern pike regulations, and some agencies manage for quality in some water bodies and do not manage northern pike at all in other water bodies. In general, states and provinces manage for quality northern pike when the public perceives the need. Experimental regulations (e.g., protected slot‐length limits) currently are being used on some waters. Although regulations can help create quality northern pike populations, angler compliance and environmental constraints on growth and recruitment also influence the success of management programs. Managers and anglers must realize the limitations of regulations for restructuring northern pike populations.

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