Chapter 10

Harvest and Exploitation

Pa t r i c k J. Sc h m a l z , An d r e w H. Fa y r a m , Da n i e l A. Is e r m a n n , St e v e n P. Ne w m a n , a n d Cl a y t o n J. Ed w a r d s

10.1 INTRODUCTION

From the time that the first peoples of North America developed the means to harvest fish, and sauger have been sought after as both a source of food and for recreation. In this chapter we outline the development and current status of aboriginal, commercial, and recreational walleye and sauger in North America. In addition, we describe how ex- ploitation is managed within each of these fisheries, and summarize current research related to walleye and sauger exploitation in North America.

10.2 ABORIGINAL FISHERIES OF WALLEYE AND SAUGER

10.2.1 Development of Fisheries

It is difficult to determine when aboriginal North Americans began to use walleye and sauger for subsistence. Instead, we must rely on archeological evidence to establish time periods when occurred within the geographic range of walleye and sauger and then assume that some of the fish being harvested during that period were walleye and sauger. Archaeological evidence suggests that by as early as 3000 B.C. aboriginal North Americans in the Great Lakes region had already developed several types of fishing gear for use in the upper Great Lakes, including spears, gaffs, hook and line, and weirs. In the lower Great Lakes, nets may have been used for fishing as early as 2500 B.C. but were not used until sometime between 300 and 200 B.C. in the upper lakes (Bogue 2000). Some of the more detailed accounts of aboriginal fishing, including fishing methods and species caught, were made by European explorers of North America. In 1695 French explor- ers documented a settlement of Ottawa Indians on Lake Huron who were fishing with nets and appeared to have chosen the site due to the abundance of fish, including (Kinietz 1940). In addition, Bogue (2000) quoted journal writings of an early explorer who reportedly witnessed torchlight spearing (though not explicitly stated as fishing for walleyes or saugers) in the Fox River of Green Bay during the 1840s. Rogers (1972) noted that before 1830 the Ojibwa of northwestern Ontario used gill nets and hook-and-line techniques in early summer

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to fish for walleyes and other species, but as big game became increasingly scarce, fishing became a year-round activity and the tribal members began to use spears, fish traps, and weirs. Rostlund (1952) published a detailed evaluation of freshwater fish use by aboriginal North Americans. Approximately 24 aboriginal tribes inhabited locations within the native range of walleye and sauger, but only those in the Great Lakes and central Canada appeared to rely substantially on fish for food. Tanner (1987) also stated that tribes of the northern Great Lakes, particularly the Ottawas, Ojibwas, and Hurons, relied historically on fish as a primary source of food. The effect of subsistence fishing that occurred before European colonization is difficult to determine. However, there are several reasons to believe that populations were not overfished. Aboriginal North American population density was low with respect to the distribution of fish resources (Nielsen 1999; Bogue 2000). People did not have the means to transport or store large quantities of fish, thereby making large harvest impractical (Bogue 2000). Aboriginal North Americans often attached religious or spiritual importance to fish; these beliefs may have prevented overharvest of fish resources (Nielsen 1999; Bogue 2000). Other indirect evi- dence that aboriginal North Americans did not overharvest fish populations are the many ac- counts made by early European explorers describing large numbers of fish and the presence of very large individual fish (Kinietz 1940; Bogue 2000).

10.2.2 Present Aboriginal Walleye and Sauger Fisheries

10.2.2.1 Harvest Rights of Current Aboriginal North Americans

Aboriginal walleye and sauger fisheries currently exist in a number of states and prov- inces in the United States and Canada. Tribal harvest occurs within established reservation boundaries and in many areas outside of these boundaries such as in waters that are part of land areas ceded by aboriginal people but where rights to fish were retained. For example, in the United States, off-reservation rights to fish were retained in treaties signed by several tribes and the U.S. Government, and upheld in subsequent litigation (Busiahn 1989; BIA 1991). Specifically, the treaties of 1836, 1837, 1842, and 1854 reserved the rights of some aboriginal tribes to harvest walleyes and other fish in areas of , Wisconsin, and Min- nesota. Subsequent treaties or state rulings lead some to believe the tribes no longer retained rights to harvest walleyes and other fish; however, these rights have been upheld in federal court several times since the 1980s (Busiahn 1989; BIA 1991; WDNR 1997; GLIFWC 2007). Since the court cases have been settled in Wisconsin and Minnesota and a “Consent Decree” has been negotiated and agreed to in Michigan, off-reservation tribal harvest has occurred. In Canada, the right to harvest walleyes, saugers, and other fish by aboriginal people is held above those of nonaboriginal Canadians, and may be based on treaties, Natural Resource Transfer Agreements in the Prairie Provinces, aboriginal title, and contemporary agreements (Notzke 1994). Beginning in the late 1700s and continuing into the 1900s numerous treaties were signed with tribes that included rights to fish across Canada covering areas varying in geographic range. For example, 36 treaties were negotiated in Ontario between 1763 and 1929 (Hansen 1991; Notzke 1994). The Natural Resource Transfer Agreements of 1929 that conveyed the ownership of natural resources from the federal government to the provinces of Alberta, Saskatchewan, and Manitoba included aboriginal fishing rights and made them province-wide (Notzke 1994). Similar to the United States, the degree to which off-reserva- Harvest and Exploitation 377 tion fishing rights were protected from provincial and federal law was challenged on several occasions (Hansen 1991; Notzke 1994). Finally, in 1982, the Constitution Act recognized and affirmed the rights of all aboriginal peoples of Canada, thus protecting their rights to fish in the Canadian Constitution (Ashcroft et al. 2006). Further, in 1985, section 88 of the Indian Act clarified that treaty-protected fishing rights could not be affected by provincial legisla- tion (Notzke 1994). Supreme Court decisions since 1990 have further clarified the rights of aboriginal peoples protected by the Canadian Constitution, but the application of these rights to Métis—individuals of mixed European and aboriginal heritage—is still evolving (Tough 1996; Ashcroft et al. 2006).

10.2.2.2 Methods and Levels of Current Aboriginal Walleye and Sauger Harvest

The primary harvest methods employed in aboriginal North American walleye and sauger fisheries are spearing and gill-netting, although other methods such as hook and line, bow fishing, and trap-netting are also used. In Michigan, gill-netting is prohibited while trap-net- ting and seining are permitted. In Wisconsin, spearing, fyke-netting, and gill-netting are all permitted within certain guidelines. In Minnesota, gill-netting and spearing are the most com- mon methods used for walleye harvest, but hook-and-line , fyke-netting, and set-lining are all permitted under certain conditions. In Canada, gill-netting and hook-and-line angling are the primary methods for taking fish. Approximately 400 spearers from six Wisconsin Chippewa tribes participate in tribal harvest each year in the spring in relatively small lakes in the area of Michigan and Wisconsin ceded in the Treaties of 1837 and 1842 (USDOI 2007), and tribal members harvest approximately 31,000 walleyes annually during the spring spear in about 200 lakes (Krueger 2008). The fishery in these lakes generally takes place from March to April and involves a total of 2,000 nights of spearing effort (Krueger 2008). A similar number of participants harvest a similar number of walleyes from a single large lake in Minnesota. Mille Lacs Lake in Minnesota is 53,650 ha and supports an annual tribal gill- net and spear harvest of approximately 31,000 walleyes (36,750 kg, Milroy et al. 2007). The fishery in Mille Lacs Lake generally takes place in the spring from the middle of March to the middle of May with a small amount of harvest occurring in the fall from October through No- vember. Tribal fishers harvested between 2,770 and 4,180 kg/year of walleyes during 1994– 1998 from Michigan waters of the Great Lakes (Table 10.1; Summerfelt 2005). The extent of subsistence walleye and sauger harvest across much of Canada is largely unknown (Ashcroft et al. 2006) because these fisheries are self-regulated (Berkes 1979, 1989). Despite being unregulated or self-regulated, subsistence fisheries in Canada are important because some level of subsistence fishing probably occurs in most aboriginal communities, particularly in northern Canada (Berkes 1979, 1989; Hopper and Power 1991). Studies of local subsistence harvest in Canada have generally focused on specific bands or communities over short time periods. These studies have typically relied on oral interviews and surveys to estimate harvest. For example, the Webequie community of Ojibwa in northern Ontario harvested an estimated 17,420 walleyes weighing 15,150 kg for subsistence purposes during 1987–1988 (Hopper and Power 1991). An estimated 21,528 walleyes were harvested for subsistence purposes by approximately 6,500 aboriginal residents in eight communities of the Mushkegowuk Region in the Hudson Bay and James Bay areas in Ontario in 1990 (Berkes et al. 1994). Ten aborigi- nal communities across Manitoba were surveyed in 1984 regarding wildlife harvest (Wagner 1986). The number of fish harvested the previous year ranged from 270 to 34,500 per com- 378 Chapter 10

Table 10.1. Tribal harvest (kg) of walleyes from Michigan waters of Lakes Huron, Michigan, and Superior, 1994–1998 (adapted from Summerfelt 2005).

Lake 1994 1995 1996 1997 1998

Huron 2,658 2,332 2,446 1,902 1,513 Michigan 1,506 479 1,377 605 716 Superior 16 761 263 704 541 Total 4,180 3,572 4,086 3,211 2,770

munity and included a possible 14 different species (Wagner 1986). Walleyes were consumed by all 10 communities and saugers were consumed by three communities on Lake Winnipeg (Wagner 1986). Tribal exploitation of walleye is generally lower than recreational angler exploitation in waters where both fisheries exist. Tribal exploitation of adult walleyes in Wisconsin waters supported primarily by natural reproduction averaged 6.2% (range, 0.03–49.0%; N = 371) during 1989–2006 (USDOI 2007). Similarly, tribal exploitation of adult walleyes in Wis- consin waters supported primarily through stocking averaged 4.9% (range, 0.03–27.0%, N = 83) during the same time period (USDOI 2007). Walleye exploitation rates associated with recreational anglers averaged 7.6% between 1995 and 2002 (Hansen and Hennessy 2006). Tribal exploitation rates in Mille Lacs Lake, Minnesota, are approximately 4–5% for walleyes age 3 and older, while total exploitation rates averaged 11.2% from 1998 to 2008 (Minnesota Department of Natural Resources, unpublished data).

10.3 COMMERCIAL WALLEYE AND SAUGER FISHERIES

10.3.1 Development of Commercial Fisheries

10.3.1.1 The Laurentian Great Lakes

Europeans settling in North America established commercial fisheries for walleye and sauger on the Great Lakes by the late 1700s and those fisheries developed throughout the 1800s (Regier et al. 1969; Colby et al. 1979; Nielsen 1999). The first commercial hook-and- line fishery was established in eastern Lake Erie in 1795 (Regier et al. 1969; Colby et al. 1979). Commercial walleye and sauger fisheries continued to develop throughout the rest of the Great Lakes during the early and mid-1800s (Regier et al. 1969; Colby et al. 1979; Schneider and Leach 1977). Commercial seining was established in western Lake Erie in 1815 (Regier et al. 1969). Beginning in 1836 the first commercial pound-net fisheries developed on Lake Ontario, followed by the first gill-net fisheries in eastern Lake Erie in 1852, the first fyke-net fisheries in Lake Erie by the 1880s, and the first trap-net fisheries in 1890 in western Lake Erie and Lake Huron (Regier et al. 1969; Colby et al. 1979). Gill nets eventually became the most commonly used commercial gear in the Great Lakes, followed by trap nets (Colby et al. 1979). The Great Lakes historically supported the most productive commercial walleye and sauger fisheries in North America, with some level of harvest occurring on all five lakes (Fig- ure 10.1). In Lake Ontario, commercial harvest records date back to 1867 and, until 1917, Harvest and Exploitation 379

Lake Ontario Lake Huron 150 Blue Pike 1,000 Walleye s

s Sauger Walleye 120 Walleye and Blue Pike 800 am am gr gr ilo ilo 90 600 K K of of 60 400 nds nds nds nds ousa ousa 30 200 Th Th

- -

Lake Erie Lake Michigan 15,000 Sauger 250 Blue Pike s

s Walleye 12,000 Walleye 200 am am gr gr Walleye and Blue Pike lo lo 9,000 150 Ki Ki

of of 6,000 100 nds nds nds nds ousa ousa 3,000 50 Th Th

- -

Lake St. Clair Lake Superior 150 150

s Walleye s Sauger Walleye 120 120 am am gr gr lo 90 lo 90 Ki Ki

of of 60 60 nds nds nds nds ousa 30 ousa 30 Th Th

- -

Figure 10.1. Commercial harvest (kg × 103) of walleyes, blue pike, and saugers from the Great Lakes before 1900 and by decades from 1900 to 2000. The portion of harvest labeled “Wall- eye and Blue Pike” represents harvest reported as such (i.e., not separated). Data were from Baldwin et al. (2002).

walleye harvest was reported along with that of blue pike. During that time period walleye and blue pike annual harvests in Lake Ontario were as high 0.2 million kg (Baldwin et al. 2002). Blue pike harvest peaked in 1952 at 0.3 million kg and declined to zero by 1962 (Schneider and Leach 1977; Baldwin et al. 2002). Annual walleye harvest peaked in 1958 at 76,000 kg and declined to zero by 1985 (Schneider and Leach 1977; Baldwin et al. 2002). The walleye and blue pike commercial fishery closed around 1972 in U.S. waters of Lake Ontario (S. LaPan, New York Department of Environmental Conservation, personal communication). In Lake Erie commercial harvest records date back to 1867, and until 1914 walleye harvest was often reported with that of blue pike. Commercial sauger harvest was first reported in Lake Erie in 1885. By 1914 walleye and blue pike harvest had reached 8.0 million kg (Baldwin et al. 2002). Blue pike harvest peaked in 1936 at 12.1 million kg and declined to zero by 1963 (Baldwin et al. 2002). Walleye harvest peaked at nearly 7.0 million kg in 1956 and declined 380 Chapter 10

to approximately 38,500 kg by 1971 (Baldwin et al. 2002). The commercial fishery for blue pike, walleye, and sauger closed in 1970 in Michigan, Ohio, and Ontario waters of western Lake Erie upon the discovery of mercury contamination. Commercial fisheries remain closed in Michigan and Ohio, but re-opened in Ontario in 1976 (Hatch et al. 1987). The commercial fishery in New York waters was greatly reduced in 1986 when the state prohibited the use of gill nets as commercial gear, and in 1988 the sale of walleye was prohibited, essentially eliminating the fishery (D. Einhouse, New York Department of Environmental Conservation, personal communication). In Lake St. Clair commercial harvest records date back to 1874. Walleye harvest peaked at 0.4 million kg in 1891 and declined to 19,500 kg in 1970 when the fishery closed upon the discovery of mercury contamination; no commercial harvest has occurred since 1970 (Johnston 1977; Baldwin et al. 2002). In Lake Huron commercial harvest records date back to 1867. Walleye harvest peaked at nearly 1.6 million kg in 1899 and declined to approximately 35,000 kg by 1972, and sauger harvest peaked at 95,000 kg in 1930 and declined to zero in 1941 (Baldwin et al. 2002). Commercial fisheries for walleye and sauger were closed in the U.S. waters of Lake Huron in 1970 (Mrozinski et al. 1991). In Lake Michigan commercial harvest records date back to 1885. Commercial walleye harvest peaked in 1950 at 0.6 million kg, declined to zero in 1987 and has remained at very low levels (Baldwin et al. 2002), prob- ably due to incidental harvest. The commercial walleye fishery closed in Michigan waters of Lake Michigan in 1969 and in Wisconsin waters in 1979 (Schneider et al. 1991). In Lake Superior commercial harvest records date back to 1868. Annual walleye har- vest peaked in 1966 at nearly 0.2 million kg, declined rapidly to 4,000 kg in 1970, and has remained below 10,000 kg over the last three decades (Baldwin et al. 2002). Sauger harvest peaked at 56,000 kg in 1956 and declined to zero in 1972 (Baldwin et al. 2002). The commer- cial walleye fishery was closed in Wisconsin waters of Lake Superior during 1940–1942 and then permanently in 1956 (Baldwin et al. 2002). The walleye was granted sport fish status in Michigan in 1969, protecting it against commercial harvest in four of the five Great Lakes and Lake St. Clair (Baldwin et al. 2002). Commercial was identified as a factor contributing to the decline of walleye stocks in all five Great Lakes, although the effects of exploitation varied among and within lakes (Schneider and Leach 1977).

10.3.1.2 History of Commercial Fisheries in Inland Waters

The majority of commercial harvest of walleyes and saugers in waters outside of the Great Lakes has occurred on large inland lakes in Canada, with some additional historical commercial harvest occurring on a small number of Minnesota lakes and the Mississippi River. Commercial walleye and sauger fisheries began in Canada and along the upper Missis- sippi River in the late 1800s and were well established by the early 1900s (Carlander 1954; and Olver 1977; Adams 1978; Ashcroft et al. 2006). Since their development, com- mercial walleye fisheries in Manitoba have been the largest inland commercial fisheries in North America (Lemm 2002). Walleye harvest records were first reported for Lake Winnipeg in 1885 and began on Lake Winnipegosis in 1890 (Lemm 2002). By 1925 approximately 20 large lakes in northern Manitoba were being commercially fished; this num- ber increased to 40 lakes by 1938, and more than 300 lakes were being commercially fished for walleyes by the early 1980s (Lemm 2002). The peak province-wide walleye and sauger harvest of 17.5 million kg occurred in 1941 (Lemm 2002); Lake Winnipeg alone accounted Harvest and Exploitation 381 for 5.8 million kg of walleye and sauger (Heuring 1993). After 1963 overexploitation of wall- eyes and saugers in Lakes Winnipeg and Winnipegosis was blamed for substantial declines in the commercial harvest and the fishery was closed in many areas in 1970 and 1971 due to mercury contamination (Lemm 2002). Upon re-opening of walleye and sauger commercial fisheries in Manitoba during 1972, commercial harvest approached 16 million kg by 1980 (Lemm 2002). Ontario’s inland commercial walleye and sauger fisheries were spread throughout much of the northern part of the province. Although harvest occurred in several lakes, most of the harvest occurred on a small number of waters, including Lake of the Woods, Lac Seul, Rainy Lake, and Lake Nipigon (Adams and Olver 1977). Province-wide commercial harvest of walleyes from Ontario’s inland lakes declined from more than 1 million kg in 1960 to around 0.4 million kg in 1972 (Colby et al. 1979). During the period 1917–1973, average annual commercial walleye harvest for Lac Seul was more than 72,700 kg and was more than 49,000 kg for Lake Nipigon (Adams and Olver 1977). Commercial fishing in Saskatchewan began around 1885 and was well established by 1920. Commercial harvest records date back to the 1920s and walleye and sauger harvest increased province-wide from an average annual har- vest of more than 0.1 million kg in the 1920s to a high of more than 0.9 million kg annually in the 1960s (Ashcroft et al. 2006). Commercial walleye harvest in Alberta came primarily from three large lakes: Lake Athabasca, Lesser Slave Lake, and Lake Bistcho (Lemm 2002). Commercial fishing in Lake Athabasca began in 1926 and catch has been recorded each year (Bradford and Hanson 1990a). Commercial walleye harvest ranged from an annual average of around 3,700 kg during 1935–1943 to 46,500 kg during 1951–1966, 85,400 kg during 1967– 1974, and around 75,000 kg through the 1980s (Bradford and Hanson 1990a). Commercial fishing harvest was not monitored on Lesser Slave Lake until 1942 and extensive illegal fish- ing occurred during a period in the mid-1960s, when walleye fisheries were collapsed; thus, no accurate harvest numbers are available (Bradford and Hanson 1990b). During the 1980s, the annual average commercial harvest of walleyes from Lesser Slave Lake was approximately 30,000 kg (Bradford and Hanson 1990b). Province-wide walleye harvest in Alberta declined from nearly 0.5 million kg in 1960 to 41,000 kg in 1973 (Colby et al. 1979). Overharvest by commercial fishing contributed to the decline and loss of walleye populations in Alberta dur- ing the mid-1900s (Lemm 2002). Minimal commercial walleye harvest occurred historically in Québec and the Northwest Territories (Lemm 2002). The inland Canadian commercial walleye and sauger fisheries were mostly with gill nets (Lemm 2002). Commercial fishing records from the upper Mississippi River date back to 1894 (Car- lander 1954). Walleye and sauger commercial harvest was included with that of yellow perch, was a very small component of the overall commercial harvest (0.2 million kg or 3.5% in 1894, 49,900 kg or 1% in 1899, 10,000 kg or 0.2% in 1922), and was zero by 1931 (Carlander 1954). Gear types employed on the Mississippi River included seines, trap nets, trammel nets, gill nets, and setlines (Carlander 1954).

10.3.1.3 Historical Commercial Fisheries in Lake of the Woods and Rainy Lake

Commercial walleye and sauger fisheries on Lake of the Woods and Rainy Lake, both of which are on the international border between Ontario and Minnesota, were historically large inland commercial fisheries outside of the Great Lakes and offer the most detailed histori- cal information regarding commercial harvest. Commercial fisheries on Lake of the Woods 382 Chapter 10

began in 1888 in Minnesota with no restrictions. Commercial fisheries in Ontario waters began in 1892 with limits on the amount of gear that license holders could fish (Schupp and Macins 1977). Pounds nets and gill nets were the primary commercial gear types used on Lake of the Woods with gill nets being used more frequently through time due to increased capture efficiency for walleyes and saugers (Schupp and Macins 1977). Commercial walleye harvest reached a high of more than 0.8 million kg in 1935, while commercial sauger harvest remained below 0.2 million kg, averaging less than half of that from 1926 to 1973, despite saugers being four to six times more abundant than walleyes in certain areas on the lake (Schupp and Macins 1977). Commercial walleye harvest declined from the highs experienced in the 1930s through the early 1970s (Schupp and Macins 1977). It is not believed that com- mercial harvest alone led to declines in walleye fisheries in Lake of the Woods, but rather a combination of commercial and recreational exploitation (Schupp and Macins 1977). The state of Minnesota reduced the amount of gill nets licensed in 1947 and then stopped issuing new commercial licenses in 1948. The Minnesota commercial fishery was eventually closed in 1986, but Ontario’s commercial fishery continues today. The first commercial fishery on Rainy Lake began in 1885 and was a pound-net fishery targeted primarily at lake sturgeon. A trap-net fishery targeting primarily ciscoes followed in the early 1900s, and by 1904 the first gill-net fishery was established (Chevalier 1977). By the 1920s gill nets were the primary gear used to target walleyes, and reliable harvest records were first recorded in 1924 (Chevalier 1977). Walleye harvest was highest in 1924 at 0.15 mil- lion kg and steadily declined to 19,000 kg in the early 1970s, probably due to overexploitation resulting from both commercial and recreational fisheries (Chevalier 1977).

10.3.2 Present Commercial Walleye and Sauger Fisheries

Commercial walleye and sauger harvest in North America still occurs in Canadian waters of the Great Lakes and other large inland lakes including Lakes Winnipeg, Winnipegosis, and Manitoba, Lake of the Woods, Rainy Lake, Eagle Lake, Lake Nipigon, and others. The vast majority of commercial harvest occurs with the use of gill nets and effort is generally quanti- fied as the number of kilometers of gill net deployed (Thomas et al. 2010). The Ontario waters of Lake Erie have supported a mean annual commercial harvest of approximately 1.9 million walleyes (2.2 million kg) between 2001 and 2009 (Thomas et al. 2010), which was 96% of the Great Lakes commercial walleye harvest (Table 10.2) and nearly 40% of the total commercial walleye harvest in Canada (Lemm 2002). There are approximately 500 active commercial fishing licenses in Ontario with an annual landed value of Can$36.4 million (Ontario Ministry of Natural Resources, unpublished data). Commercial walleye harvest in Manitoba represents approximately 44% (averaging 3.4 million kg annually during 1980–1999 and 5.2 million kg annually during 2000–2009) of the total commercial walleye harvest in Canada and is concentrated in Lakes Winnipeg, Winnipegosis, and Manitoba (Lemm 2002; www.freshwa- terfish.com; Table 10.3). Commercial sauger harvest in Manitoba has averaged approximately 0.5 million kg but has generally declined during 2000–2009 (www.freshwaterfish.com; Table 10.3). Walleyes account for approximately 34% of all commercial fish harvest in Manitoba while saugers account for 5% (Manitoba Water Stewardship 2008). The economic activity associated with Manitoba commercial fisheries is substantial with 3,185 individuals partici- pating and an annual landed value of walleyes of approximately Can$20 million (Manitoba Water Stewardship 2008). Commercial walleye harvest in Saskatchewan represents approxi- Harvest and Exploitation 383

Table 10.2. Commercial harvest (kg × 103) of walleyes from Ontario waters of the Great Lakes, 2001–2009. Data provided by the Ontario Ministry of Natural Resources.

Year Lake Superior Lake Huron Lake Erie Lake Ontario Total

2001 0.25 109 1,720 18 1,848 2002 0.52 83 1,782 7 1,873 2003 0.18 82 1,787 6 1,875 2004 0.03 83 1,279 7 1,369 2005 0.18 60 2,904 9 2,974 2006 0.28 104 3,618 11 3,733 2007 0.17 95 2,623 15 2,733 2008 0.30 93 2,258 19 2,371 2009 0.53 113 1,596 22 1,732 mately 8% (averaging 0.6 million kg annually during 1980–1999 and 0.5 million kg annually during 2000–2009) of the total commercial walleye harvest in Canada, most of which comes from 50 lakes in the province (Lemm 2002; Ashcroft et al. 2006; www.freshwaterfish.com; Table 10.3). The commercial sauger fishery in Saskatchewan has been small in recent years, at or around 1,000 kg during 2000–2009 (www.freshwaterfish.com; Table 10.3). Commer- cial walleye harvest in Alberta and the Northwest Territories combine for 1.5% (averaging 110,000 kg annually during 1980–1999) of commercial walleye harvest in Canada, and there has been no recent commercial harvest of saugers from these waters (www.freshwaterfish. com; Table 10.3). Harvest of wild walleyes in Canada overall has been characterized as being at or near maximum levels (Lemm 2002). Commercial fishing for walleyes in the United States occurs primarily in Lake Erie, although the magnitude of this fishery has been greatly curtailed in the past several decades in favor of recreational fisheries. Currently, in the U.S. waters of Lake Erie, commercial walleye harvest occurs in Pennsylvania and in 2006 only one commercial trap-net operation targeted walleyes, harvesting a total of 1,280 kg (Pennsylvania Fish and Boat Commission 2007).

10.4 RECREATIONAL WALLEYE AND SAUGER FISHERIES

10.4.1 Development of Recreational Walleye and Sauger Fisheries

Angling existed before the first European settlers came to North America, but the first great improvements were made after the publishing of Izaak Walton’s book The Compleat Angler in 1836. Angling changed from a subsistence fishery to recreation as the need to fish for food decreased, and the use of fisheries for recreation increased beginning after World War II (Nielsen 1999). Walleye has now become one of the primary target species for anglers in much of North America, particularly in northern latitudes and in the interior of the continent where walleyes are endemic. The relative popularity of walleye fishing closely follows their geographical dis- tribution (see Chapter 4). Throughout their native and introduced ranges walleyes ranked first or second among anglers in popularity (Quinn 1992). In the United States as a whole (exclud- 384 Chapter 10 - .fresh Total 5,701 5,108 5,142 5,619 5,620 5,956 6,442 6,196 6,235 584 691 782 777 594 317 169 131 281 Northwestern Ontario 10.9 0.45 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Northwest Territories 30.8 34.0 44.9 26.8 25.4 20.9 28.1 12.0 11.0 0 0 0 0 0 0 0 0 0

Alberta Walleye 45.8 49.9 44.0 43.1 67.1 62.6 34.9 28.0 32.0 Sauger 0 0 0 0 0 0 0 0 0 Saskatchewan 462 586 627 632 499 460 436 410 462 0.91 0.91 0.91 1.36 0.91 0.91 0.91 1.00 1.00 Manitoba 5,151 4,438 4,425 4,917 5,028 5,412 5,943 5,746 5,730 583 690 781 777 593 316 168 130 280 ) of walleyes and saugers from commercial fisheries in central and northern Canada by fiscal year from 2000– commercial fisheries in central and ) of walleyes and saugers from 3 Fiscal year 2000–01 2001–02 2002–03 2003–04 2004–05 2005–06 2006–07 2007–08 2008–09 2000–01 2001–02 2002–03 2003–04 2004–05 2005–06 2006–07 2007–08 2008–09 Catch statistics (kg × 10 Table 10.3. Table 01 to 2008–09, compiled from quarterly reports of the Freshwater Corporation (Government Canada); available at: www waterfish.com. Harvest and Exploitation 385 ing the Great Lakes), walleyes represent the sixth most sought-after fish species in freshwater, with 3.2 million anglers spending over 46 million days targeting walleyes in 2001 (USDOI et al. 2001). Within the Great Lakes, walleyes increase in popularity, ranking second behind black (centrarchid) bass with 0.5 million anglers spending over 5.5 million days targeting walleyes in the same year (USDOI et al. 2001). Reducing the focus further, walleyes are the most targeted single species of fish in Wisconsin among anglers stating a preference (McCla- nahan 2003). Similarly, in Alberta, more walleyes were reported caught by anglers than any other species of fish (Park 2007).

10.4.1.1 Economic Impact of Recreational Walleye and Sauger Fisheries

The economic impacts of walleye fishing are considerable. Commercial fisheries that exist primarily in Lake Erie and large lakes in Canada are valued at approximately Can$60 million annually (Manitoba Water Stewardship 2008; Ontario Ministry of Natural Resources, unpublished data). However, for walleyes generally has a greater econom- ic impact than does commercial fisheries. For example, the primary target species for anglers in Lake Winnebago, Wisconsin, is walleye and the recreational fishery there has an estimated value of US$234 million annually (Winnebago County University of Wisconsin Extension 2006) and the economic value of the recreational fisheries of Lake Erie have been estimated to be US$600 million where walleye and sauger are the primary targeted species (USDOI et al. 2008). In Alberta during 2005, recreational fishing (with walleyes being the most caught species) was estimated to result in direct expenditures and purchased-based investments of over Can$441 million (Park 2007). Even on smaller scales, the economic importance of wall- eye fisheries is considerable. Obara (1999) reported the economic activity associated with an 8-week recreational walleye season in Norris Reservoir, Tennessee, to be US$740,000.

10.4.2 Effort, Harvest, and Exploitation in Recreational Walleye and Sauger Fisheries

With few notable exceptions, walleye and sauger fisheries in North America are open ac- cess. Some level of angler effort can cause exploitation rates to be high enough to create un- sustainable walleye fisheries (Sullivan 2003) even in the presence of catch-and-release-only fisheries (Post et al. 2002). Catch per effort is related to fish density in the following way:

C = qN, f where C is the catch, f is angler effort, q is the catchability coefficient, andN is density (Ricker 1975). Exploitation is simply expressed as the ratio of C:N. Therefore, exploitation (u) is re- lated to effort as follows:

u = fq

The catchability coefficient, the proportion of the population that is removed with one unit of effort, is often assumed to be constant although several studies have demonstrated that this is not always the case. Hansen et al. (2005) and Shuter et al. (1998) both demonstrated 386 Chapter 10

that catchability was negatively related to population density, resulting in catch rates that did not decline linearly with declining population density. One of the consequences of this nonlin- ear relationship is that, while exploitation will still be positively related to effort, exploitation levels in open-access recreational fisheries may be more elevated than expected at low popula- tion densities, thereby magnifying the risk of stock collapse at low population densities. Complicating the management of exploitation rates in open-access recreational fisheries is the fact that effort directed at walleyes can change dramatically in a given waterbody over time, thereby affecting exploitation levels. For example, Lathrop et al. (2002) documented a fourfold increase in angler effort directed at walleyes from the mid-1980s to the mid-1990s in Lake Mendota, Wisconsin. Similarly, angler effort and exploitation vary by geographic loca- tion and depend on factors such as regulation type (Beard et al. 2003a), presence or absence of stocking (Fayram et al. 2006), and fish density (Cox et al. 2002; Beard et al. 2003b) making the prediction and management of exploitation difficult. In an effort to minimize the local- ized impacts of angler effort, Ontario began a management program that applied standardized regulations to 20 large areas of the province in 2008. By managing waterbodies in close prox- imity to each other in a similar fashion, the effects of localized movements of anglers caused by the popularity of particular lake-specific regulations can be minimized. Angler effort varies dramatically over the geographic range occupied by walleyes. Ap- proximately 1.7 h/ha were directed at walleyes in Lake Erie based on data in Thomas et al. (2008), although this may not be the best way to compare effort with other walleye lakes since large areas in Lake Erie contain little suitable walleye habitat. Obara (1999) reported 4.7 h/ha of effort during an 8-week period in Norris Reservoir, Tennessee, in 1995. Hansen and Hen- nessy (2006) reported the average amount of angler effort directed toward walleyes based on 14 creel surveys in northern Wisconsin was 24.2 h/ha. In Mille Lacs Lake, Minnesota, angler effort averaged 28.1 h/ha during winter and 23.1 h/ha during open-water months for the 6-year period covering 2004–2009 (Minnesota Department of Natural Resources, unpublished data). During the 1980s and 1990s, angler effort averaged 9.6 h/ha across a number of relatively un- productive lakes in Alberta (Sullivan 2003). Although this level of effort is substantially lower than has been documented in many other walleye fisheries, it was deemed to be unsustainably high and was blamed for the collapse of many of those populations (Sullivan 2003). Since exploitation rates are linked to angler effort it is logical that exploitation also varies dramatically over the geographic range occupied by walleyes. In a comprehensive compari- son of the exploitation rates of 46 North American walleye populations, Baccante and Colby (1996) found that exploitation ranged from 3% to 55% with a median rate of 21%. Willms and Green (2007) reported an extremely high exploitation rate of 81–95% in Canadarago Lake, New York, during the 1988 fishing season. Similarly, Pegg et al. (1996) estimated a relatively high sauger exploitation rate of 50% in the lower Tennessee River between 1992 and 1993. Although the most common concern among fisheries managers is overexploitation, and justifiably so, there are strategies that rely on increased harvest and exploitation of certain components of the fish population (see Chapter 11). One of the man- agement objectives of protective slot limits and other similar regulations for a fish species is to increase exploitation on fish in smaller size ranges to increase the proportion of larger-sized fish in the population and the amount of prey available to larger fish in an effort to increase growth rates (Brousseau and Armstrong 1987; Noble and Jones 1993). If exploitation is not increased on the smaller fish these types of regulations can fail to meet management objec- tives (Fayram and Schmalz 2006). Harvest and Exploitation 387

10.5 MANAGEMENT OF EXPLOITATION

A variety of approaches exists for managing or regulating exploitation in walleye and sauger fisheries, ranging from very simple approaches that require relatively little investment in time and resources to very intensive management regimes that require substantial investment of agency resources. Managing exploitation is often difficult because in open-access fisheries, indirect man- agement tools, such as and size limits, are almost exclusively employed. Additionally estimates of exploitation rates are often lacking for individual walleye and sauger stocks. For ex- ample, in the lake-rich regions of the upper U.S. Midwest and some Canadian provinces the sheer number of viable walleye fisheries precludes intensive monitoring of individual populations. Fur- thermore, the data requirements (e.g., creel surveys) to estimate exploitation rates are extensive and costly. Consequently, management decisions are often made merely under the assumption that exploitation is an important factor influencing the status of walleye and sauger populations. The vast majority of walleye and sauger fisheries in North America are strictly recre- ational in nature and management of exploitation is best defined as perfunctory, typically taking the form of state- or province-wide harvest regulations that regulate the number (i.e., bag limits) and, in some cases, the length of walleyes (i.e., length limits) that can be removed by an individual angler (see Chapter 11 for details on specific types of regulation and methods of assessment). The success of these “blanket” regulations in managing exploitation on indi- vidual water bodies is largely unknown. In an increasing number of cases population-specific harvest regulations have been used in managing exploitation in walleye and sauger fisheries (e.g., Beard et al. 2003a; Sullivan 2003; Isermann 2007; see Chapter 11). These regulations are typically bag or length limits that are more restrictive than prevailing statewide or provincial regulations. In some cases these regulations are enacted based on evidence that exploitation rates threaten the sustain- ability of a walleye or sauger population (e.g., Maceina et al. 1998; Sullivan 2003), but often they are implemented with the goal of increasing population abundance and size structure to meet angler desires for more and larger fish (Fayram et al. 2001; Isermann 2007). In some fisheries these regulations may be enacted to prevent the harvest from exceeding specified safe harvest levels (Beard et al. 2003a; Radomski 2003); this typically occurs in mixed fisher- ies where recreational, commercial, and subsistence fishing occur in various combinations. In some walleye populations regulations that only restrict the harvest of individual anglers (i.e., bag and size limits) have not always been effective in managing exploitation (Radomski 2003; Sullivan 2003) because they do not explicitly restrict total harvest or angler effort (Post et al. 2002) or they are undermined by illegal harvest (Sullivan 2002) or mortality associated with the of walleyes (Radomski 2003; Sullivan 2003). Recreational fisheries for walleyes and saugers are largely harvest-oriented. The increase in walleye and sauger harvest restrictions over the past several decades has resulted in an- glers releasing a large portion of their total catch in some fisheries (Sullivan 2003; Reeves and Bruesewitz 2007). Consequently, the mortality of walleyes and saugers that have been released by anglers must be considered when managing exploitation and, in certain walleye fisheries like Mille Lacs Lake, Minnesota, protocols are in place to account for this mortality (Reeves and Bruesewitz 2007). In some cases management of walleye and sauger exploitation is a relatively intensive pro- cess. This typically occurs for mixed fisheries, where subsistence or commercial fishers exploit the fishery along with recreational anglers. This process often culminates in establishing safe 388 Chapter 10

harvest levels and harvest quotas for specific fisheries. This process typically includes intensive population sampling, relatively frequent efforts to estimate population size or spawning stock biomass via mark–recapture, and the use of various age-structured models to simulate the effects of different exploitation policies. Four examples of walleye fisheries where relatively intensive protocols have been used in managing exploitation are described in the following sections.

10.5.1 Management of Exploitation of Mixed Fisheries

10.5.1.1 Lake Erie

In terms of total harvest, Lake Erie currently supports the largest walleye fishery in North America. The fishery consists of two primary components, a recreational fishery that occurs primarily in U.S. waters and a commercial gill-net fishery that occurs in Canadian waters. Management of the Lake Erie walleye fishery falls under the direct jurisdiction of the four U.S. states that border the lake (Michigan, Ohio, Pennsylvania, and New York) and the province of Ontario. These agencies work collaboratively through their representatives on the Lake Erie Committee (LEC) of the Great Lakes Fishery Commission to establish an annual Total Al- lowable Catch, which is used by each jurisdiction to regulate their expected harvest that year. Annual harvest of walleyes on Lake Erie is regulated largely based on estimates of walleye abundance derived from age-structured population models and recruitment projections (Lake Erie Committee 2005). These models incorporate walleye catch data from multiple gill-net and angler surveys that are conducted on an annual basis by each state or provincial resource agency. Data compilation and modeling are conducted by members of the Lake Erie Walleye Task Group, an advisory group consisting of fisheries biologists from each state or province (Thomas et al. 2010). Model simulations are conducted to estimate the number of age-2 and older walleyes in the western and central basins of the lake. Allowable harvest is currently established using a sliding scale, where recommended fishing mortality rates are based on specified categories of estimated walleye abundance, an approach referred to as the “slidingF ” policy. For example, if simulations indicate that walleye abundance in Lake Erie is less than 15 million fish, the population is classified as being in a “crisis” state and the lowest level of fish- ing mortality (F = 0.1) is employed in establishing allowable harvest. Conversely, if population projections exceed 40 million walleyes, the highest allowable level of fishing mortality F( = 0.4) is employed. After completing this analysis the Task Group then makes recommendations to the Lake Erie Committee regarding allowable harvest. Once the allowable harvest has been established, the harvest is allocated based on surface area existing within the boundaries of each state or province. Surface area used in harvest allocation includes only that portion of the lake designated as the “walleye habitat zone” (i.e., waters < 13 m depth), a zone that encom- passes the entire western basin and most of the central basin of the lake. Commercial fishing is allowed to occur until the harvest quota for Canadian waters has been reached. In U.S. waters, walleye harvest is regulated via daily bag limits and length limits; these regulations may be adjusted on an annual basis to ensure that harvest remains below the allocated quota.

10.5.1.2 Mille Lacs Lake, Minnesota

Mille Lacs Lake is a large (53,650 ha) natural lake located in east-central Minnesota. Beginning in 1997, annual walleye harvest quotas have been used to allocate harvest between Harvest and Exploitation 389 recreational anglers and Ojibwe subsistence netters and spearers. The management objective for the mixed fishery on Mille Lacs Lake is to prevent the annual harvest (tribal and angling combined), including catch-and-release angling mortality (Reeves and Bruesewitz 2007), from exceeding the safe harvest level. A constant exploitation rate policy is used on Mille Lacs Lake and an exploitation level of 24% of the walleyes 356 mm and longer is deemed safe, which is originally based on F0.1 as calculated by Deriso (1987). Age-structured population models that incorporate annual assessment data (gill-netting, electrofishing, and ), angler creel survey, and tribal harvest data are used to esti- mate the walleye population size annually. State and tribal biologists evaluate the population models and other data to set the safe harvest level (24% of walleyes 356 mm and longer). Once the safe harvest level is agreed to, it is allocated among the Ojibwe bands that maintain harvest rights and the state of Minnesota for anglers (Figure 10.2). To date tribal declarations have been based on 5-year harvest management plans. From 2002 to 2007 tribal declara- tions were constant at 45,360 kg. A new tribal harvest management plan beginning in 2008 modified tribal declarations based on performance. The 2008 tribal declaration was 55,566 kg, increased to 57,380 kg in 2009, and to 60,100 kg in 2010 and to the plan’s maximum of 64,637 kg in 2011 because some of the bands reached at least 90% of their share of the tribal allocation. The state of Minnesota’s allocation is the difference between the safe harvest level and the tribal declaration. In most years once the state’s angler allocation was determined, size-based

300 Tribal Allocaon State Allocaon 250 ) 3

10 200 (x es lley 150 Wa of s am 100 gr lo Ki

50

- 1997 1998 1999 2000 2001 2002 2003 200420052006 2007 2008 2009 2010 2011

Figure 10.2. State (light bars) and tribal (dark bars) allocation of walleyes from Mille Lacs Lake, Minnesota, 1997–2011. The combination of allocations equals the annual safe harvest level, equivalent to 24% of the estimated population of walleyes 356 mm and longer based primarily on age-structured models. 390 Chapter 10

angling regulation options were evaluated that optimized angling opportunities based on the current walleye population status. Final regulations were then determined with public input. The result was eight different regulations to start the angling season in 14 years, and two regulation changes within the season resulting in stricter size limits (Table 10.4). Presently the Minnesota Department of Natural Resources is seeking ways to stabilize angling regulations on Mille Lacs Lake.

10.5.1.3 Small Lakes in Northern Wisconsin

In more than 900 northern Wisconsin lakes ranging in size from approximately 11 to 6,100 ha, the state of Wisconsin works with the Great Lakes Indian Fish and Wildlife Commission and tribal management agencies to distribute walleye harvest between recreational anglers and the Ojibwe people who participate in a subsistence fishery, which consists primarily of spearing during the spawning season. These mixed walleye fisheries are managed to prevent annual exploitation rates of adult fish from exceeding 35%. A risk criterion is used to allow

Table 10.4. Summary of walleye angling regulations for Mille Lacs Lake, Minnesota, 1998– 2009.

Fishing year Angling regulation

1998 381-mm minimum length limit; 6 fish bag limit. 1999 356–508-mm harvest , only one longer than 660 mm; 6-fish bag limit. 2000 356–457-mm harvest slot limit, only one longer than 711 mm; 6-fish bag limit. 2001 406–508-mm harvest slot limit, only one longer than 711 mm; changed to 406–457-mm harvest slot, only one longer than 711 mm on June 5; changed to one longer than 762 mm (still 406–457-mm harvest slot) on July 10; changed to 356–457-mm harvest slot limit, only one longer than 711 mm on December 1; 6-fish bag limit. 2002 356–406-mm harvest slot limit, only one longer than 711 mm; 4-fish bag limit. 2003 432–711-mm protected slot limit, only one longer than 711 mm; 4-fish bag limit. 2004–2006 508–711-mm protected slot limit, only one longer than 711 mm; changed to 559–711-mm protected slot limit, only one longer than 711 mm on July 16; changed back to 508–711-mm protected slot limit, only one longer than 711 mm on December 1; 4-fish bag limit. 2007 508–711-mm protected slot limit, only one longer than 711 mm; changed to 356–406-mm harvest slot limit, only one longer than 711 mm on July 16; changed back to 508–711-mm protected slot limit, only one longer than 711 mm December 1; 4-fish bag limit. 2008–2009 457–711-mm protected slot limit, only one longer than 711 mm; 4-fish bag limit. 2010–2011 457–711-mm protected slot limit, only one longer than 711 mm; changed to 508–711-mm protected slot limit, only one longer than 711 mm on July 15; changed back to 457–711-mm protected slot limit, only one longer than 711 mm on December 1; 4-fish bag limit. Harvest and Exploitation 391 for uncertainty in meeting this objective and mandates that exploitation of adult walleyes in these fisheries should not exceed 35% in more than 1 out of 40 lakes (USDOI 1991). To ac- complish this objective, state and tribal biologists use an innovative approach incorporating walleye population estimates, the use of harvest quotas, and a sliding bag-limit system used to regulate harvest by recreational anglers. The initial step of this process is to establish an estimate of adult walleye abundance in each lake for each year. In some cases, this is directly accomplished using mark–recapture studies conducted during early spring (Hansen et al. 2000). Using predetermined adjust- ment factors (Hansen et al. 1991), these direct population estimates are used for 2 years after the mark–recapture process occurred. However, given the large number of lakes in- volved, recent population estimates are not available for each lake. In lakes where a popula- tion estimate has not been made in the last 2 years, adult walleye abundance is predicted from lake area and the primary source of walleye recruitment (i.e., natural reproduction or stocking) in the lake using a log–linear model (Hansen 1989; Nate et al. 2001). Based on these estimates of adult walleye abundance, safe harvest levels (i.e., harvest quotas) are es- tablished for each lake based on the 35% exploitation rate and the 1 out of 40 risk criterion (Staggs et al. 1990). Following this process, tribes declare a percentage of the safe harvest that will be targeted primarily by spearing fisheries. The state of Wisconsin must then establish recreational har- vest regulations for each lake. This is accomplished using a sliding bag-limit system, where daily bag limits for recreational anglers can be set between zero and five walleyes per angler, depending on the percentage of safe harvest declared by the tribes (Beard et al. 2003a). The effectiveness of this management system is then evaluated by estimating exploitation rates in both the spearing and angling fisheries.

10.5.2 Active Management of Exploitation in Alberta

In recent decades many popular walleye fisheries in Alberta have declined or collapsed due to a combination of low productivity and increasing fishing pressure (Sullivan 2003). Consequently, the province established an active management system for these fisheries that consisted of a three-step iterative cycle as follows: (1) describe the stock status, (2) develop a harvest policy for that stock, and (3) implement harvest regulations to achieve the selected harvest policy. Stock status is described using a suite of biological reference points that are based largely on population demographics and includes a measure of angling success. For example, populations exhibiting a relatively narrow distribution of ages with no apparent strong year-classes, fast growth, early maturation, and poor angler catch rates are classified as “collapsed.” These stock status designations then dictate the harvest policy and regulations that are to be applied to an individual stock. Unfortunately, this system has not always allevi- ated problems with overexploitation, as illegal harvest and mortality resulting from catch and release of walleyes has been sufficient to undermine the effectiveness of harvest regulations (Sullivan 2003). Consequently, the province of Alberta has begun to experiment with limited- entry fisheries, where anglers must purchase a tag to allow them to harvest walleyes from certain waters. 392 Chapter 10

10.6 CURRENT RESEARCH OF WALLEYE AND SAUGER EXPLOITATION

10.6.1 Research of Sustainable Rates of Exploitation

The amount of harvest and exploitation that can be sustained varies based on the amount of production of the walleye or sauger population. Factors such as the number of growing degree-days (Baccante and Colby 1996; see Chapter 7) and available habitat, including light penetration and nutrient availability (Lester et al. 2004; see Chapter 5), affect walleye pro- duction and influence the sustainable exploitation rate. Less productive systems that gener- ally occur toward the northern edge of the geographical distribution probably have lower sustainable exploitation rates than do more southerly populations. Exploitation levels of joint recreational–tribal fisheries for walleyes in Wisconsin and Minnesota seem to be sustainable based on the lack of walleye population collapses in the vast majority of managed waters. Schueller et al. (2008) found that the exploitation rate of 35% used in Wisconsin to manage mixed angling and spearing fisheries resulted in 0% probability of extinction and 0% prob- ability of decline in simulations using an age-structured population model. In fact, results suggested northern Wisconsin walleye populations could be sustained at exploitation rates of 61% for an unregulated angling fishery, 84% for an angling fishery with a 381-mm minimum length limit, or 72% for a spearing fishery, though Schueller et al. (2008) recommended ex- perimental evaluation of modeling results. Overexploitation has been blamed for the collapse of some walleye and sauger popula- tions. In Savanne Lake, Ontario, Colby and Baccante (1996) associated experimental exploita- tion levels of 17–20% with a simulated “overharvest” and suggested that a sustainable harvest rate to maximize production was 1 kg/ha. Although overexploitation was blamed as a potential cause of the lack of recovery of a depressed sauger population in the lower Yellowstone River that occurred in the late 1980s, Jaeger et al. (2005) estimated exploitation to be relatively low (18.6%). Jaeger et al. (2005) concluded that entrainment in diversions were a more likely explanation for the lack of sauger recovery. Exploitation levels in combined recreation- al–tribal–commercial fisheries have exceeded sustainable exploitation levels in some instances (Beard et al. 2003b) and population collapses have resulted in some cases (Gangl and Pereira 2003). Recreational angling alone has, in some instances, exceeded sustainable exploitation levels and has been blamed for collapses of walleye populations in several lakes in Alberta (Sullivan 2003). In addition, more subtle but persistent reductions in population abundance resulting from recreational fishing have been described by Post et al. (2002).

10.6.2 Effects of Exploitation on Walleye and Sauger Population Dynamics

Exploited walleye populations have demonstrated changes in particular characteristics associated with the degree of exploitation. The characteristics that change in response to in- creased exploitation are those affected by density-dependent processes (see Chapter 9). As exploitation increases, density generally decreases. Spangler et al. (1977) suggested that in- creased growth rates and variability in recruitment and decreased age at maturity would re- sult from increasing exploitation. More recently, Gangl and Pereira (2003) compared several biological performance indicators in a collapsed walleye population to walleye populations that were regarded to have low to moderate exploitation levels and concluded that increased Harvest and Exploitation 393 growth, spawning-stock age diversity, and variation of population abundance as well as re- duced age and length of females at 50% maturity were characteristics associated with the overexploited population. However, these measures may only respond when walleye popula- tions are exploited to the point of collapse, as Sass et al. (2004) only found a relatively weak relationship between density and growth over a wide range of population densities.

10.6.2.1 The Response of a Naturally Reproducing Walleye Population to 35% Annual Exploitation

In 1993 the Wisconsin Department of Natural Resources initiated a study to evaluate the of northern Wisconsin walleye populations, including determining the short- term responses of a walleye population to 35% annual exploitation. Adult walleyes in Big Crooked Lake, a 276-ha drainage lake located in north-central Wisconsin with restricted ac- cess, were experimentally exploited at 35% per year for 10 consecutive years beginning in 1996. Objectives were to determine the effects of 35% annual exploitation on mean length at age 3–6, adult density and biomass, female rate of maturity, potential egg deposition, and recruitment to the fall age-0 year-class. The Big Crooked Lake walleye population responded to the 35% exploitation rate rap- idly. Mean length of age 3–6-year-old fish increased significantly after 4 years, and averaged nearly 64 mm longer during the 35% exploitation years (Figure 10.3). By 2002–2003 some females were reaching 508–533 mm in length by age 5, whereas during pretreatment years, few fish reached 381–406 mm. During the pretreatment years, less than 0.5% of the catch in fyke nets was greater than 508 mm, but by 2003, 22% exceeded 508 mm in length.

500

450

400 m) (m 1993-1997

th 350 1998-2008 ng Le 300

250

200 3 456 Age (yr)

Figure 10.3. Mean length at ages 3–6 for walleyes from Big Crooked Lake, Wisconsin, 1993– 2008. Pretreatment lengths (dashes) include 1993–1997 and posttreatment lengths (solid squares) include 1998–2008. Error bars represent the 95% confidence interval of the mean. 394 Chapter 10

Although the average adult walleye density during the treatment years was 34% lower than during the pretreatment years (Figure 10.4), rate of maturity and fecundity increased rapidly after treatment began. Consequently, the average biomass of adult walleyes during the treatment years was 23% higher than the pretreatment average (Figure 10.4). The adult den- sity became relatively stable beginning in 2001, averaging about 6.8 fish/ha compared with 15.5 fish/ha during pretreatment years. Continued exploitation at 35% annually appeared to result in earlier maturity of female walleyes, an apparent spike in egg deposition, and decreased stability in recruitment to fall age 0 in Big Crooked Lake. Mature age-4 fish were not found in 1997, but within 2 years, more than 30% of the fish were mature by age 4. In 1997, females did not reach 100% matu- rity until age 8, but by 2000, 100% maturity was reached at age 5 (Table 10.5). Although total egg deposition did not change significantly with time, it did increase rapidly after treatment began (Figure 10.5). The total egg deposition peaked in 2000, and then began to stabilize along with abundance. Walleye recruitment to fall age 0, which was relatively stable during the pretreatment years, increased rapidly and became extremely erratic under the 35%/year exploitation rate (Figure 10.6).

10.7 SUMMARY AND CONCLUSIONS

Walleye and sauger have long been targeted for subsistence, commercial purposes, and recreation. Aboriginal fisheries for walleyes and saugers still exist in many of the same regions they have existed for centuries. Commercial fisheries are still able to exist in many of the same waters they always have, despite several declines due to overexploitation. Recreational fisheries

25 25 Biomass

20 Abundance 20 e e 15 15 ar ar ect hect h r r r r 10 10 pe pe

5 5 Pounds Number

0 0

Figure 10.4. Abundance and biomass of adult walleyes from Big Crooked Lake, Wisconsin, 1993–2007. Harvest and Exploitation 395

Table 10.5. Percentage of female walleyes mature for ages 3–6 from Big Crooked Lake, Wis- consin, 1997–2007.

Age 3 Age 4 Age 5 Age 6 Year % mature % mature % mature % mature

1997 0.0 0.0 85.7 96.4 1998 0.0 18.2 53.3 93.5 1999 0.0 32.5 97.0 90.9 2000 0.0 57.1 100.0 100.0 2001 20.0 50.0 100.0 100.0 2002 0.0 69.2 100.0 100.0 2003 0.0 34.5 100.0 100.0 2004 0.0 89.5 100.0 100.0 2005 0.0 100.0 100.0 100.0 2006 8.3 83.3 100.0 100.0 2007 13.9 78.0 98.0 100.0

180

160

140

120 ons)

illi 100 (m 80 ggs e of 60

40 Number

20

0 1997 199819992000 2001 200220032004 200520062007 Year Figure 10.5. Walleye egg deposition from Big Crooked Lake, Wisconsin, 1997–2007. 396 Chapter 10

350

300

e 250 ar ct he r 200 pe

es ey

ll 150 wa 0

e- 100 Ag

50

0 1993 1995 1997 1999 2001 2003 2005 2007 Year Figure 10.6. Numbers of age-0 walleyes per hectare from Big Crooked Lake, Wisconsin, 1993– 2007.

for walleyes and saugers flourish across the native and introduced ranges of both species. The ability of these fisheries to exist and in many cases co-exist successfully is due primarily to suc- cessful management, which includes cooperative efforts by often competing interests (Pinkerton 1989). Managing harvest and exploitation is a central task of fisheries management agencies. Even in the extreme case of catch-and-release fisheries, some fishing-induced “harvest” -re sults from hooking mortality. Lack of control of harvest and excessive exploitation rates have resulted in the historic collapse of many commercial and recreational walleye fisheries. How- ever, when harvest and exploitation is limited to predetermined levels, sustainable fisheries can result.

10.8 ACKNOWLEDGMENTS

We thank Tom Heinrich (Minnesota Department of Natural Resources), Donald Schreiner (Minnesota Department of Natural Resources), Lee Kernen (Wisconsin Department of Natu- ral Resources, retired), David Fielder (Michigan Department of Natural Resources), Thomas Goniea (Michigan Department of Natural Resources), James Johnson (Michigan Department of Natural Resources), Steven LaPan (New York Department of Environmental Conserva- tion), Donald Einhouse (New York Department of Environmental Conservation), Jana Lantry (New York Department of Environmental Conservation), Brian Lantry (U.S. Geological Sur- Harvest and Exploitation 397 vey, Lake Ontario Biological Station), Charles Madenjian (U.S. Geological Survey, Great Lakes Science Center), Christopher Vandergoot (Ohio Department of Natural Resources), Peter Ashcroft (Saskatchewan Environment), David McLeish (Ontario Ministry of Natural Resources), Steve Currie (Ontario Ministry of Natural Resources), and Bruce Barton for as- sistance with locating information regarding current and historical commercial fisheries. We also thank Kevin Kayle (Ohio Division of Wildlife), Joseph Hennessy (Wisconsin Department of Natural Resources), Richard Bruesewitz (Minnesota Department of Natural Resources), and Mike Sullivan (Alberta Sustainable Resource Development, Fish and Wildlife Division) for assisting with the descriptions of intensive walleye management programs.

10.9 REFERENCES

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