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495 Rehabilitation of Lake Sturgeon in the Great Lakes: Making Progress Bruce Manny and Lloyd Mohr Introduction The Lake Sturgeon (Acipenser fulvescens) is indigenous to North America and all of the Great Lakes (Scott and Crossman 1998). Few freshwater fish in North America have a wider geographic range than the Lake Sturgeon. It is found in three drainage basins: the Mississippi River, the Great Lakes, and Hudson Bay (Priegel and Wirth 1971). Sadly, most Lake Sturgeon populations throughout their entire home range have been impacted by human activity, reducing and, in some cases eliminating, entire populations. The greatly diminished abundance and status of Lake Sturgeon in the Great Lakes is largely a function of their life history characteristics, historic over-exploitation, and habitat loss, including complete destruction of or reduced access to tributary habitat (Auer 1996a, 1999a; Petersen et al. 2007). Auer (1999a) called the Lake Sturgeon “a unique and imperiled species,” a very accurate description of both the fish and its current status. Its uniqueness has made it both susceptible to human stresses and, ironically, more tolerant of other stresses. Although its value to various fisheries in the Great Lakes basin has been limited in recent decades, its importance as an indigenous species, its role in the Great Lakes fish community, and its ecological, social, and economic appeal have ensured it did not disappear from the face of the earth. Management of Lake Sturgeon is still seen as a priority issue for most fishery agencies throughout the Great Lakes basin. The Decline of Lake Sturgeon in the Great Lakes According to historic records, the Lake Sturgeon was very numerous before European settlement in North America (Harkness and Dymond 1961). There is sufficient information regarding Native American harvesting of Lake Sturgeon to suggest sturgeon were widely distributed and that abundance, at least of spawning aggregations, was very high (Auer 1999a; Harkness and Dymond 1961). The development of commercial fisheries (beyond local supply) in the mid-nineteenth century in the Great Lakes basin provided some of the first quantitative information with respect to relative abundance of Lake Sturgeon in the Great Lakes. Bruce Manny and Lloyd Mohr 496 Ironically, that source of information also described, in detail, the overexploitation that took place in the 1880s and 1890s (Auer 1999a; Baldwin et al. 1979). As commercial fishing began in the Great Lakes, Lake Sturgeon were viewed by fishermen as an unwanted bycatch. At first, Lake Sturgeon were utilized only for their fatty oil content, rather than their eggs or flesh. As other uses for Lake Sturgeon were discovered (Post 1890) and markets developed for smoked flesh and caviar, in the early 1880s, targeting by commercial fisheries began (Carey 2005). The rise and fall of the Lake Sturgeon catches is well documented by Auer (1999a) and Baldwin et al. (1979). Of note is the short period of time during which the collapse occurred. In 1885, production peaked, when more than 3.7 million kg were harvested from the Great Lakes (Baldwin et al. 1979). By 1900, harvest had dropped by more than an order of magnitude, to 0.25 million kg. In less than fifty years, beginning in the 1850s, Lake Sturgeon transitioned from a nuisance species of high abundance, to a highly prized commercial species, to a depleted fishery resource of little consequence (fig. 1). Auer (1999a) provides a comprehensive review of the historic commercial fisheries in the Great Lakes, including the decline described. During the same time, the Great Lakes were experiencing some of the most dramatic and significant changes to fish habitat in history (Kelso et al. 1996) and at a very fast rate. Settlements were being built FIG. 1. Historical catch of Lake Sturgeon (Acipenser fulvescens) in U.S. and Canadian waters. REHABILITATION OF LAKE STURGEON 497 throughout the Great Lakes basin, many in the vicinity of rivers and river mouths. The need for wood, water power (for milling and sawing), and transportation led to the modification of many river systems. The construction of dams, during this time, was considered a key factor in the collapse of Atlantic Salmon (Salmo salar; Danfield 1985). These structures no doubt impacted other river spawning species in the basin. By the middle of the nineteenth century, most rivers containing traditional spawning grounds for Lake Sturgeon had several dams and mills along their length (Harkness and Dymond 1961). Kelso et al. (1996) found a direct association between habitat destruction and declining commercial fishing, prior to 1920. Only the connecting waters (i.e., St. Marys...

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