Northern Pike: Ecology, Conservation, and Management History

3. Conservation and Management of Northern Pike

91 91 Chapter 3 Conservation and Management of Northern Pike Conservation and Management Strategies in Minnesota Current Conservation Issues Loss of critical habitat has been an important issue for maintaining northern pike populations (Casselman and Lewis 1996; Margenau et al. 2008). Draining and filling of wetlands and so-called “improvement” of shorelines for lake homes have been increasingly responsible for lost habitat in urban,agricultural,and other highly developed areas of Minnesota. Shoreline and related land development removes vegetation, reduces water quality, and reduces dissolved oxygen levels in the sediments (Burns 1991; Cross and McInerny 1995; Radomski and Goeman 2001). A study of habitat used by young-of-the-year pike in Spirit Lake, Iowa (Bryan and Scarnecchia 1992),found pike only along natural shorelines ; the fish avoided developed lakeshore. An essay by Clifford Brynildson titled “What’s Happening to Northern Pike Spawning Grounds?” published in the Wisconsin Conservation Bulletin in 1958, documents that we have been aware of the problem of habitat loss for at least half a century. Yet,shoreland zoning regulations, which were first adopted in 1970, have failed to stem the loss of habitat. Where habitat has been altered in southern Minnesota, stocking is a last resort for maintaining pike populations. Fry are conservation and management of northern pike c o n s e r v a t i o n a n d m a n a g e m e n t o f n o r t h e r n p i k e 92 stocked directly from hatcheries, or fry or gravid (egg-bearing) adults are stocked into managed wetlands,where the young pike are allowed to grow for a few weeks to small fingerling size before being released into adjoining lakes. Future habitat alteration may also include changes in thermal habitat (and even prey species associations) related to global climate change. Such responses have already been detected in Lake Windermere, England, since the 1990s (Winfield et al. 2008). Where good natural habitat for northern pike exists, natural reproduction is usually not a limiting factor. In fact, a common phenomenon in many small central and northern Minnesota lakes is large numbers of small, stunted (slow-growing) pike. From a fisheries management viewpoint, these populations are difficult to manage because they arise from some combination of overharvest of large fish, a lack of appropriate-sized prey fish, and habitat characteristics that fail to promote good growth (Pierce et al. 1995; Paukert et al. 2001). Maintaining an appropriate balance of large pike, in the face of heavy fishing pressure on large fish, may be a key problem for managing pike populations. Stocking has been an unsatisfactory management tool in such lakes and has only worsened problems with prey fish communities and poor growth rates of pike. The Evolution of Management Strategies in Minnesota The historical progression of management techniques for northern pike in Minnesota is an interesting story of changing perspectives in conservation. Early in the history of the state, when human population densities were low, pike were abundant enough to be considered rough fish along with suckers and bullheads. Minnesota ’s Fish Commission,in its first annual report in 1874,regarded the pike as a “calamity” of nature, and the commissioners were “fully convinced that every pickerel of the state simply occupies the room of a better fish” (Hoffbeck 2001). As human densities began to increase,pike became more valued,and it was recognized c o n s e r v a t i o n a n d m a n a g e m e n t o f n o r t h e r n p i k e 93 that they might not fare well under unfettered exploitation. The earliest management,then,consisted of regulations that restricted techniques for catching pike, closed down fishing during spring spawning periods, and began to limit people from harvesting overly large numbers of fish in a single day. Meanwhile,climatic conditions were changing in Minnesota. Amounts of rainfall that the state received declined during the early 1900s and were very low during the drought years of the 1930s. Similarly,lake levels and runoff declined from 1920 to 1940. We cannot document what happened to pike populations, but it is likely that low water levels led to relatively low pike population numbers. During this period,attempts were made to take pike eggs,incubate them in hatcheries,and stock the fry...