Sometimes known as Pike, Dory, Glass Eye, Green Pike, Gray Pike, Jack Salmon, Marble Eye

Transcription

1 WALLEYE GREAT LAKES Sander vitreus Sometimes known as Pike, Dory, Glass Eye, Green Pike, Gray Pike, Jack Salmon, Marble Eye SUMMARY Walleye is a freshwater species of fish found throughout the northern part of North America. In the Great Lakes, Walleye have been the target of recreational and commercial fisheries for hundreds of years, and today most Walleye are commercially caught from the Canadian side of Lake Erie. Walleye grow quickly and reach sexual maturity at a young age, but habitat degradation and high fishing pressure have decreased their abundances over time. Walleye have a medium abundance overall across the Great Lakes, but population sizes varies between and within lakes. Walleye are typically caught using gillnets, which have a low to medium impact on bottom habitat. Criterion Points Final Score Color Life History Abundance Habitat Quality and Fishing Gear Impacts Management 2.50 Bycatch 2.50 Final Score 2.30 Color

2 LIFE HISTORY Core Points (only one selection allowed) If a value for intrinsic rate of increase ( r ) is known, assign the score below based on this value. If no r-value is available, assign the score below for the correct age at 50% maturity for females if specified, or for the correct value of growth rate ('k'). If no estimates of r, age at 50% maturity, or k are available, assign the score below based on maximum age Intrinsic rate of increase <0.05; OR age at 50% maturity >10 years; OR growth rate <0.15; OR maximum age >30 years Intrinsic rate of increase = ; OR age at 50% maturity = 5-10 years; OR a growth rate = ; OR maximum age = years Intrinsic rate of increase >0.16; OR age at 50% maturity = 1-5 years; OR growth rate >0.30; OR maximum age <11 years. Sexual maturity in Walleye is reached between 2-4 years for males, and 3-8 years for females at a length of >30 cm for both sexes (Scott and Crossman 1973; Colby et al. 1979). Growth rates have been estimated to range from 0.3 to 0.4 (He et al. 2005) and female Walleye have higher growth rates both before and after they reach sexual maturity (Henderson et al. 2003). Walleye typically live around 7 years (Mecozzi 1989), although in Lake Erie they can live past 20 (Anonymous 2010), and reach a maximum length of 107 cm fork length (Scott and Crossman 1998) and weight of 11 kg (IGFA 1991). There have been changes in growth and age at maturity over time in some areas such as Lake Ontario (Bowlby et al. 2010). For example, after 2000, growth increased by around 10% per year and the age and maturity for both sexes declined by around one year in this lake (Bowlby et al. 2010). Growth rates of Walleye are linked to their abundance, with slower growth occurring at high abundances (Hartman and Margraf 1992). Points of Adjustment (multiple selections allowed) Species has special behaviors that make it especially vulnerable to fishing pressure (e.g., spawning aggregations; site fidelity; segregation by sex; migratory bottlenecks; unusual attraction to gear; etc.) Species has a strategy for sexual development that makes it especially vulnerable to fishing pressure (e.g., age at 50% maturity >20 years; sequential hermaphrodites; extremely low fecundity) Species has a small or restricted range (e.g., endemism; numerous evolutionarily significant units; restricted to one coastline; e.g., American lobster; striped bass; endemic reef fishes).

3 -0.25 Species exhibits high natural population variability driven by broad-scale environmental change (e.g. El Nino; decadal oscillations). Changes in spring warming of Lake Erie over time have been shown to affect Walleye recruitment levels (Busch et al. 1975; Roseman et al. 1999; Shuter et al. 2002) and could therefore affect population abundances. Because this will likely increase abundance, no points are subtracted Species does not have special behaviors that increase ease or population consequences of capture OR has special behaviors that make it less vulnerable to fishing pressure (e.g., species is widely dispersed during spawning) Species has a strategy for sexual development that makes it especially resilient to fishing pressure (e.g., age at 50% maturity <1 year; extremely high fecundity). Walleye spawning typically occurs in spring when water temperatures begin to rise (Colby et al. 1979), with most spawning occurring between a range of 6-11 C (Scott and Crossman 1973). Spawning can begin as early as January in southern areas (U.S) and go through June in northern areas (Canada) (Craig 1987). Spawning typically occurs at depths less than 5 m (Busch et al. 1975; Roseman et al. 1996) over several days generally at night (Ryder 1977). Females produce an average of 50,000 eggs (dependent on the size and age of the female) (Mecozzi 1989), and the eggs hatch within 14 to 21 days (Ney 1978). This is a medium level of fecundity so no points were added. Typical spawning habitats include shallow areas near the shore, dam faces that have rocky substrate and good water circulation, and shoals (Eschmeyer 1950; Johnson 1961; Colby et al. 1979). Reproduction can be inhibited when ph levels drop below 6.0 (Anthony and Jorgenson 1977). Walleye tend to return to their original natal rivers to spawn (Jennings et al. 1996; Stepien and Faber 1998). In Ohio, U.S., main spawning areas for Walleye are mid-lake reefs and in tributaries of the Maumee, Detroit and Sandusky rivers (Mion et al. 1998; Zhao et al. 2009; Manny et al. 2010) and Ontario reefs (Anonymous 2010). In these rivers, larvae are usually hatched from mid-april through late May (Mion et al. 1998). In eastern Lake Erie, spawning areas include the New York shoreline, Grand River and nearby shoals (LaMP 2010). In Lake Superior, the Nipigon River and St. Louis River are thought to be main spawning grounds for Walleye in Nipigon Bay (Goodyear et al. 1982; LSBP 2008) Species is distributed over a very wide range (e.g., throughout an entire hemisphere or ocean basin; e.g., swordfish; tuna; Patagonian toothfish). Walleye are found throughout the northern part of North America (Dupont et al. 2007), and found in all of the Great Lakes (Roseman et al. 2010a). In Lake Erie, there are two genetically distinct populations, one in the western basin and one in the eastern (Stepien and Faber 1998). These populations have different mortality rates, distribution patterns and abundance levels (Haas et al. 2003; Ryan et al. 2003; WTG 2004). For example, western basin Walleye move throughout the lake, while the eastern basin population

4 remains only in that section of the lake. In Lake Huron there are three localized populations, one in each of the three basins of the Lake (LHBP 2008). Additional genetic evidence suggests that although some Walleye may move from lake to lake during the summer, there are many distinct populations (Stepien et al. 2010). We consider this a medium range and have therefore not added any points Species does not exhibit high natural population variability driven by broad-scale environmental change (e.g., El Nino; decadal oscillations) Points for Life History ABUNDANCE Core Points (only one selection allowed) Compared to natural or un-fished level, the species population is: 1.00 Low: Abundance or biomass is <75% of BMSY or similar proxy (e.g., spawning potential ratio) Medium: Abundance or biomass is % of BMSY or similar proxy; OR population is approaching or recovering from an overfished condition; OR adequate information on abundance or biomass is not available. Walleye have a medium abundance overall across the Great Lakes, but population sizes can vary between and within lakes. The abundance of Walleye in Lake Erie, where the majority are caught (Kinnunen 2003), started a long-term decline in the 1990 s (LaMp 2008) due to increased fishing pressure, poor recruitment and environmental changes (Locke et al. 2005; Roseman et al. 2008). Abundance estimates of Lake Erie Walleye from 1999 to 2002 were 50% less than the abundance level in 1989 but a strong 2003 year class did help bring the population up to more desirable levels (Thomas and Haas 2005; LaMP 2008). Changes in recruitment over time have been the primary factor affecting variations in Walleye abundance in Lake Erie (Busch et al. 1975; Shuter and Koonce 1977; Roseman et al. 2008). However, declines of Walleye in Lake Erie may have also been influenced by the colonization of zebra mussels, as seen in other lakes (Rutherford et al. 1999; Thomas and Haas 2003). In 2009, Ontario harvested 104% of their total allowable catch of Walleye in Lake Erie (Thomas et al. 2010). The 2010 spawning abundance in Lake Erie was higher than during 14 of the past 32 years, but the spawning-recruitment relationship is not well understood in this lake (Thomas et al. 2010). In Lake Erie, there is a western and eastern population

5 of Walleye. Abundance in 2010 of Walleye in the western population is estimated at almost 20 million fish (Thomas et al. 2010). Managers consider this number of fish to indicate that the fishery is in a rehabilitative state and of low quality (Locke et al. 2005; Thomas et al. 2010), although this classification is currently being revisited by the Lake Erie Committee and may actually be too pessimistic (Anonymous 2010). In 2009, it was estimated that 3.6 million Walleye were in the eastern basin of Lake Erie (Thomas et al. 2010). Genetic information has identified that the western basin population of Walleye make up the majority of both the western and eastern basin fisheries (Gatt et al. 2003), indicating that most Walleye in Lake Erie originate from the western population. In Lake Huron, annual Walleye yield between 1992 and 2004 was far below the target level, due mostly to reduced recruitment and overexploitation to some extent (Fielder et al. 2010). In Lake Ontario, Walleye fisheries exist mainly in Bay of Quinte and the eastern end of the lake. Abundance of young-of-the-year Walleye declined by 75% after the 1990 s but overall abundance has remained high enough to sustain recreational fisheries in these regions (Bowlby et al. 2010). Walleye populations in most areas of Lake Michigan are depressed or beginning to enter the rehabilitation state, while two populations, Fox River and Little Bay de Noc are considered rehabilitated or starting the late rehabilitation stage respectively (Kapuscinksi et al. 2010). Abundances of Walleye in Lake Superior remain below historic levels (Schram et al. 2010). In the Canadian waters, the Black Bay, which used to support the largest commercial Walleye fishery in Lake Superior (Canada), and Nipigon Bay populations collapsed in the 1960 s and have not recovered (Scharm et al. 2010). The St. Louis population (US waters) is only taken through recreational fishing and although the status of the population is not known, research indicates they have a low fishing mortality rate (Schram et al. 2010). The Chequamegon Bay population, which collapsed in the s, can now only be maintained through stocking of fingerlings (Schram et al. 2010). Lake Superior has been closed to commercial fishing in US waters since 1955 due to these low abundances (Schram et al. 2010) High: Abundance or biomass is >125% of BMSY or similar proxy. Points of Adjustment (multiple selections allowed) The population is declining over a generational time scale (as indicated by biomass estimates or standardized CPUE). Abundance estimates from trap nets in Michigan waters of Lake Erie showed no real trend for Walleye from 1999 to 2003 but estimates from gillnet surveys showed a steady decline from 2000 to 2003 (Thomas and Haas 2005). In 2009, gillnet catch per unit effort

6 of Walleye in western Lake Erie was 8% less than in 2008 but was 13% higher than the long-term lake-wide average (Thomas et al. 2010). Specifically, effort decreased in 3 out of 4 management units lake wide (Thomas et al. 2010). Fluctuations in population size are caused by changes in recruitment of Walleye (Thomas et al. 2010). We have not subtracted any points because there is no clear trend in abundance declines over time Age, size or sex distribution is skewed relative to the natural condition (e.g., truncated size/age structure or anomalous sex distribution). Estimates from Lake Erie (Michigan) showed declines in the abundance of age 2+ fish after 1996 (Thomas and Haas 2005). Catches of age 0 Walleye in Lake Erie (Ohio) were less than 25% of the 15 year average in 2006 (Bur et al. 2007). In 2009, age 6 Walleye made up 49% of the total commercial harvest in Lake Erie, while age 2 Walleye represented 27% of the total catch (Thomas et al. 2010). Age 3-5 Walleye have low abundances in Lake Erie and therefore represent a very low portion of the total catch (Thomas et al. 2010). The average age of Walleye caught in Ontario s commercial fisheries during 2009 in Lake Erie ranged from 4.7 to 7.5 years, which was a decrease from 2008 but higher than the long-term average (Thomas et al. 2010). In the eastern basin, 44% of the population is made up of age 2 animals and 34% age 6 (Thomas et al. 2010). The age structure of Walleye populations varies naturally and between populations and regions, which could also influence the changes seen over time (Anonymous 2010). Tagging studies have indicated that large female Walleyes from the western basin make up the majority of the western basin population found in eastern basin fisheries (Haas et al. 2003; Wang et al. 2007). Over the entire lake, the average age of Walleye increases from the west to the east and is highest in the eastern basin (WTG 2004; Wang et al. 2007) Species is listed as "overfished" OR species is listed as "depleted", "endangered", or "threatened" by recognized national or international bodies Current levels of abundance are likely to jeopardize the availability of food for other species or cause substantial change in the structure of the associated food web. Walleye are considered to be critically important to the ecology of Lake Erie. Their role in community-structuring has been reduced in recent years as Walleye have moved into deeper waters, due to increased transparency of the water column, and replaced blue pike, which are now biologically extinct in this lake (Ryan et al. 2003; LaMP 2008; Roseman et al. 2008). Evidence from other lakes suggests species such as northern pike and yellow perch initially increase in numbers after the removal of Walleye (Fruetel 2002). However, within ten years northern pike and yellow perch numbers returned to normal (Fruetel 2002). Information from Lake Erie suggests forage fish abundances decline as Walleye

7 populations increase in size (Knight et al. 1984). In Lake Huron, increases in Walleye abundance have coincided with declines in alewives (LHBP 2008; Fielder et al. 2007). Food preferences change as Walleye grow, with zooplankton and aquatic insects being typical food for Walleye less than 1.5 cm in length, while fish become a component of their diet by 2.5 cm in length (Forney 1966; Bulkley et al. 1976; Roseman 1997). Juvenile and adult Walleye eat primarily fish but also mayfly larvae and crayfish to some extent (Priegel 1963; Wagner 1972; Johnson and Hale 1977). Typical species of fish included in their diet are young yellow perch in the northern areas (Forney 1977; Kelso and Ward 1977) and clupeids (eg. herring) and sunfish in southern areas (Miller 1967; Momot et al. 1977; Fitz and Holbrook 1978). In Lake Erie, Walleye diet is mostly made of up gizzard shad in the western region and smelt in the east (Anonymous 2010). In addition, when normal prey is scarce, Walleye have been known to become cannibalistic (Chevalier 1973; Forney 1974). In recent years round gobies, which have spread throughout Lake Erie, have become a significant prey source for Walleye and other lake predators (LaMP 2008). In Lake Erie, white perch are known to commonly prey on Walleye eggs during the spawning season, while channel catfish, Johnny darter, quillback, rock bass, round goby, sculpin, silver chub, spottail shiner, trout perch, white sucker and yellow perch also feed on Walleye eggs to a lesser extent (Roseman et al. 2006). Walleye make up a large portion of cormorants diets, and this predation has been linked to declines in subadult Walleye in Oneida Lake, an inland lake in New York (Rudstam et al. 2003). We have subtracted points because it is clear that changes in abundance of Walleye affects a number of species within a lake ecosystem The population is increasing over a generational time scale (as indicated by biomass estimates or standardized CPUE) Age, size or sex distribution is functionally normal Species is close to virgin biomass Current levels of abundance provide adequate food for other predators or are not known to affect the structure of the associated food web Points for Abundance

8 HABITAT QUALITY AND FISHING GEAR IMPACTS Core Points (only one selection allowed) Select the option that most accurately describes the effect of the fishing method upon the habitat that it affects 1.00 The fishing method causes great damage to physical and biogenic habitats (e.g., cyanide; blasting; bottom trawling; dredging) The fishing method does moderate damage to physical and biogenic habitats (e.g., bottom gillnets; traps and pots; bottom longlines). Walleye have been fished for 200 years in Lake Erie (Zhao et al. 2009) and are typically caught using gillnet gear in the US waters of the Great Lakes and trap nets and gillnets in the Canadian waters (Kinnunen 2003). The majority (~97% in 2000) of Walleye are caught in Lake Erie, followed by Lake Huron (~3%), Lake Michigan (<1%), Lake Ontario (<1%) and Lake Superior (<1%) (Kinnunen 2003). During 2000 the majority of Walleye caught in Lake Erie, were caught in Canadian waters (Kinnunen 2003). The western section of Lake Erie is where most of the Walleye are caught (Lemm 2002). Gillnets have a very low to medium impact on bottom habitat depending on where they are placed in the water column (Morgan and Chuenpagdee 2003) The fishing method does little damage to physical or biogenic habitats (e.g., hand picking; hand raking; hook and line; pelagic long lines; mid-water trawl or gillnet; purse seines). Points of Adjustment (multiple selections allowed) Habitat for this species is so compromised from non-fishery impacts that the ability of the habitat to support this species is substantially reduced (e.g., dams; pollution; coastal development). Walleye are most commonly found in lakes that are >100 ha and have an intermediate level of productivity and in cool water rivers that range from shallow to moderate depths, have large areas made up of rocky substrate and have moderate turbidity (Regier et al. 1969; Kitchell et al. 1977; Leach et. al. 1977; Schupp 1978). According to the Lake Erie Committee, adult Walleye habitat includes lake surface area that lies inside of 7 fathoms (`13 m) depth contour (Thomas et al. 2010). Juveniles and adults reside in waters <15 m deep during the day and at night move inshore to feed (Johnson and Hale 1977; Ryder 1977). Eggs have the highest survival rate over clean gravel or rubble substrates (Johnson 1961) and lower survival rates over sand and soft muck (Johnson 1961; Priegel 1970). Survival of Walleye fry is dependent on

9 streams being able to transport them downstream to lakes where they can feed (Priegel 1970; Mion et al. 1998) and fry growth is greatest in waters that are around 220 C but cannot survive in temperatures greater than 310 C (Smith and Koenst 1976; Wrenn and Forsythe 1978). Additional research has shown that the survival of larvae being transported from spawning habitat less than 100 km away is most dependent on variations in river flows, while temperature becomes more important to survival as the distance from the spawning site increases (Jones et al. 2003). Ecological modeling of the affects of lake currents in Lake Erie on Walleye, suggest that during low recruitment years, destructive bottom currents can dislodge eggs in Walleye spawning grounds and move them from suitable to unsuitable habitats and that a large number of newly hatched larvae are also moved away from suitable nursery habitats (Zhao et al. 2009). However, when recruitment was high, the effects of bottom currents on the spawning grounds were weak (Zhao et al. 2009). In addition, mild westerly or southwesterly winds during the spawning and nursery times are the most favorable to recruitment (Zhao et al. 2009). In Lake Michigan, urbanization and industrialization have degraded and/or destroyed Walleye habitat and dams have limited the movement of Walleye (LMFT 2004). In Lake Superior, managers have worked to restore Walleye habitat in Black Bay, which was destroyed by the construction of the Black Sturgeon Dam in the 1960 s (LSBP 2008). Spawning habitats of Walleye in tributaries, embayments, nearshore areas of Lake Erie have been negatively affected by sediment discharge from forestry, agriculture, dredging, and sewage disposal (LaMP 2008). Some populations of Walleye are recovering due to rehabilitation of streams (LaMP 2008) but research in Lake Erie tributary rivers has shown a decrease in larval survival associated with increases in river discharge, which result in an increase in the amount of suspended sediment (Mion et al. 1998). Mercury concentrations in Walleye have been an issue over the years and lead to the closure of the fishery in Lake Erie in 1970, which reopened in 1974 (Hatch et al. 1987; Davies et al. 1991). The majority of mercury that accumulates in fish such as Walleye is from anthropogenic sources (Glass and Sorensen 1999; Wiener et al. 2006). Analyses from lakes in Wisconsin ( ) suggest that concentrations of mercury tend to increase with the size of Walleye and that concentrations vary with latitude (Rasmussen et al. 2007). For example mercury concentrations decreased 0.5% per year in northern lakes and increased 0.8% in southern lakes from 1982 to 2005 (Rasmussen et al. 2007). These results match those of other studies that have shown a decrease in mercury concentrations of 11% from in Walleye from Minnesota (MPCA 2007) and 0.6%/year in northern Wisconsin (Madsen and Stern 2007). Mercury concentrations in Wisconsin lakes were also highest in the spring and lowest in the fall (Rasmussen et al. 2007). Mercury concentrations of Walleye in Lake Erie are monitored by the Great Lakes National Program Office and the Fisheries and Oceans Canada (LaMP 2008). In Lake Huron, larger Walleye are restricted from being caught because of their high mercury levels (LHBP 2008). Walleye are also tested for PCB s, dioxins and PAH s, along with other chemicals. Viral hemorrhagic Septicemia (VHS), killed thousands of Walleye, among other species, in Lake Huron, Lake Erie, and Lake Ontario from 2005 to 2006 (LSBP 2008).

10 -0.25 Critical habitat areas (e.g., spawning areas) for this species are not protected by management using time/area closures, marine reserves, etc No efforts are being made to minimize damage from existing gear types OR new or modified gear is increasing habitat damage (e.g., fitting trawls with roller rigs or rockhopping gear; more robust gear for deep-sea fisheries) If gear impacts are substantial, resilience of affected habitats is very slow (e.g., deep water corals; rocky bottoms) Habitat for this species remains robust and viable and is capable of supporting this species Critical habitat areas (e.g., spawning areas) for this species are protected by management using time/area closures, marine reserves, etc. There is a large sanctuary in the western basin of Lake Erie in Ontario during the spring (Anonymous 2010). In addition, the removal of the Sandusky, Ohio and Ballville River dams will open an additional 22 miles of habitat to spawning Walleye (Anonymous 2010) Gear innovations are being implemented over a majority of the fishing area to minimize damage from gear types OR no innovations necessary because gear effects are minimal If gear impacts are substantial, resilience of affected habitats is fast (e.g., mud or sandy bottoms) OR gear effects are minimal Points for Habitat Quality and Fishing Gear Impacts

11 MANAGEMENT Core Points (only one selection allowed) Select the option that most accurately describes the current management of the fisheries of this species Regulations are ineffective (e.g., illegal fishing or overfishing is occurring) OR the fishery is unregulated (i.e., no control rules are in effect) Management measures are in place over a major portion over the species' range but implementation has not met conservation goals OR management measures are in place but have not been in place long enough to determine if they are likely to achieve conservation and sustainability goals. Fisheries in Lake Erie are managed by the Lake Erie Committee (LEC), which is a binational (US and Canada) committee of state and provincial fisheries agencies that operate under the Great Lakes Fisheries Commission (Locke et al. 2005; Roseman et al. 2008; 2010b). After large declines in Walleye abundance in the 1990 s the LEC started the Coordinated Percid Management Strategy (CPMS), which included a cap on fishing (Locke et al. 2005). The CPMS was successful in stopping the decline of Walleye but not in rebuilding the population (Locke et al. 2005; Roseman et al. 2008). The Lake Erie Walleye Management Plan was created by the Lake Erie Walleye Task Group in 2005 (Locke et al. 2005). The main objectives of this plan are to define the biological and fishery quality characteristics and to design an exploitation policy that meets these objectives (Locke et al. 2005). Under this plan, the Task Group must review the following three items every 5 years: 1.) The overall status of the Walleye population 2.) The impact of long-term exploitation on abundance and demographic attributes and 3.) Determine if the exploitation policy is working (Thomas et al. 2005). The amount of Walleye that can be caught is based on a state-feedback approach where targeted fishing mortality is based on population abundance (Thomas et al. 2010). The Great Lakes Fishery Commission s Lake Erie Committee Walleye Task Group recommends the total allowable catch of Walleye for the Lake and the proportion allotted to the US and Canadian fisheries is determined using an international agreement (Lemm 2002; Thomas et al. 2010). Each area is then responsible for reporting landings and enforcement of quotas (Lemm 2002). Some waters of eastern Lake Erie, Walleye are stocked to help supplement the sport and commercial fisheries (LaMP 2008; GLFC 2010). In the Saginaw Bay, located within Lake Huron, the Michigan Department of Natural Resources has a Walleye Recovery Plan in place (LHBP 2008). The plan aims to achieve fish passage through dams, reef rehabilitation, and increasing the stocking of Walleye fingerlings (ended in 2005 after the management threshold was reached; Fielder et al. 2007), in order to produce a self-sustaining Walleye population (LHBP 2008).

12 The Lake Michigan Integrated Fisheries Management Plan, has four goals, to have a balanced, diverse and healthy ecosystem, a diverse multi-species sport fishery, a stable commercial fishery, (through regulation of harvest, and putting an emphasis on improved population assessment models, and automated setting of harvest limits through linkage with population abundance), and science based management (LMFT 2004). There is a zero harvest regulation in addition to stocking of adults in the Lower Nipigon River/Bay of Lake Superior (LSBP 2008) Substantial management measures are in place over a large portion of the species range and have demonstrated success in achieving conservation and sustainability goals. Points of Adjustment (multiple selections allowed) There is inadequate scientific monitoring of stock status, catch or fishing effort Management does not explicitly address fishery effects on habitat, food webs, and ecosystems This species is overfished and no recovery plan or an ineffective recovery plan is in place Management has failed to reduce excess capacity in this fishery or implements subsidies that result in excess capacity in this fishery There is adequate scientific monitoring, analysis and interpretation of stock status, catch and fishing effort. The Michigan Department of Natural Resources started annually assessing the status of Walleye in Lake Erie in 1978 (Thomas and Haas 2005). The Lake Erie Walleye Task Group manages several databases that contain information on harvest and population assessment surveys and tagging information (Thomas et al. 2010). The Lake Erie Committee and Walleye Task Group are working on several programs to better understand Walleye fisheries, including understand stock-recruitment relationships, determining what uncertainties exist in the fisheries models they use, determine unique populations within the lake, understand environmental variability and its effects on Walleye, and how population sizes influence Walleye recruitment (Locke et al. 2005) Management explicitly and effectively addresses fishery effects on habitat, food webs, and ecosystems This species is overfished and there is a recovery plan (including benchmarks, timetables and methods to evaluate success) in place that is showing signs of success OR recovery plan is not needed.

13 +0.25 Management has taken action to control excess capacity or reduce subsidies that result in excess capacity OR no measures are necessary because fishery is not overcapitalized. A reduction in capacity has occurred over time due to consolidations of fishing operations, fewer vessels fishing and processing plants (Anonymous 2010). In addition, Ontario has had individual transferable quotas in place since 1984 and conservative total allowable catch quotas have reduced gillnet effort (Thomas et al. 2010) Points for Management BYCATCH Core Points (only one selection allowed) Select the option that most accurately describes the current level of bycatch and the consequences that result from fishing this species. The term, "bycatch" used in this document excludes incidental catch of a species for which an adequate management framework exists. The terms, "endangered, threatened, or protected," used in this document refer to species status that is determined by national legislation such as the U.S. Endangered Species Act, the U.S. Marine Mammal Protection Act (or another nation's equivalent), the IUCN Red List, or a credible scientific body such as the American Fisheries Society Bycatch in this fishery is high (>100% of targeted landings), OR regularly includes a "threatened, endangered or protected species." 2.00 Bycatch in this fishery is moderate (10-99% of targeted landings) AND does not regularly include "threatened, endangered or protected species" OR level of bycatch is unknown. There is little information available on bycatch in Walleye fisheries. In general, gillnets catch a high amount of finfish as bycatch (Morgan and Chuenpagdee 2003). The fishery likely does not regularly capture threatened, endangered or protected species of fish. Because of the lack of information about bycatch levels, a score of 2 was awarded Bycatch in this fishery is low (<10% of targeted landings) and does not regularly include "threatened, endangered or protected species."

14 Points of Adjustment (multiple selections allowed) Bycatch in this fishery is a contributing factor to the decline of "threatened, endangered, or protected species" and no effective measures are being taken to reduce it Bycatch of targeted or non-targeted species (e.g., undersize individuals) in this fishery is high and no measures are being taken to reduce it Bycatch of this species (e.g., undersize individuals) in other fisheries is high OR bycatch of this species in other fisheries inhibits its recovery, and no measures are being taken to reduce it The continued removal of the bycatch species contributes to its decline Measures taken over a major portion of the species range have been shown to reduce bycatch of "threatened, endangered, or protected species" or bycatch rates are no longer deemed to affect the abundance of the "protected" bycatch species OR no measures needed because fishery is highly selective (e.g., harpoon; spear) There is bycatch of targeted (e.g., undersize individuals) or non-targeted species in this fishery and measures (e.g., gear modifications) have been implemented that have been shown to reduce bycatch over a large portion of the species range OR no measures are needed because fishery is highly selective (e.g., harpoon; spear). In Lake Michigan, several measures including: use of entrapment gear, elimination of large-mesh gillnets in some areas, low profile small-mesh gill nets, season/depth restrictions and diverters in trawls, have been implemented to reduce the mortality of non-target species (LMFT 2004). In addition, conservative yellow perch quotas and reduced gillnet effort have resulted in a reduction in juvenile Walleye bycatch (Anonymous 2010) Bycatch of this species in other fisheries is low OR bycatch of this species in other fisheries inhibits its recovery, but effective measures are being taken to reduce it over a large portion of the range. Walleye are incidentally taken in low levels in lake whitefish fisheries in the upper Great Lakes (Schorfhaar and Peck 1993). For example, Walleye represented 2.8% of the bycatch in the whitefish gillnet fishery of Lake Huron from 1998 to 1999 (Johnson 2004). A bycatch strategy is currently being developed for Lake Erie (Anonymous 2010) The continued removal of the bycatch species in the targeted fishery has had or will likely have little or no impact on populations of the bycatch species OR there are no significant bycatch concerns because the fishery is highly selective (e.g., harpoon; spear) Points for Bycatch

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21 Shuter, B.J., Minns, C.K. and Lester, N Climate change, freshwater fish and fisheries: case studies from Ontario and their use in assessing potential impacts, pp In: McGinn, N.A. (eds) American Fisheries Society Symposium 32: Fisheries in a changing climate, Phoenix, Arizona, USA, August 20-21, Smith, L.L., Jr. and Koenst, W.M Temperature effects on eggs and fry of percoid fishes. US Environmental Protection Agency. Ecological Research Series EPA-660/ p. Stepien, C.A. and Faber, J.E Population genetic structure, phylogeography and spawning philopatry in walleye (Stizostedion vitreum) from mitochondrial DNA control region sequences. Molecular Ecology 7: Stepien, C.A., Murphy, D.J., Lohner, R.N., Haponski, A.E. and Sepulveda-Villet, O.J Status and delineation of walleye (Sander vitreus) genetic stock structure across the great lakes. Technical Report Great Lakes Fishery Commission 69: Thomas, M.V. and Haas, R.C Status of yellow perch and walleye in Michigan waters of Lake Erie, Michigan Department of Natural Resources, Fisheries Research Report p. Thomas, M., Einhouse, D., Kayle, K., Tuner, M., Vandergoot, C., Belore, M., Cook, A., Ho, K., MacDougal, T., Soper, K., Zhao, Y. and Murray, C Report for 2009 by the Lake Erie walleye task group. Great Lakes Fishery Commission, Windsor, Ontario. 33 p. Wagner, W.C Utilization of alewives by inshore piscivorous fishes in Lake Michigan. Transactions of the American Fisheries Society 101: Walleye Task Group (WTG) , 1985, 1986, 1988, 1989, 19990, 1991, 1993, 1994, 1995, 1996, 1997, Report of the Lake Erie Walleye Task Group to the Standing Technical Committee, Lake Erie Committee of the Great Lakes Fishery Commission. Wang, H., Rutherford, E.W., Cook, H.A., Einhouse, D.W., Haas, R.C., Johnson, T.B., Kenyon, R., Locke, B., and Turner, M.W Movement of walleyes in Lake Erie and St. Clair inferred from tag return and fisheries data. Transactions of the American Fisheries Society 136: Wiener, J.G., Knights, B.C., Sandheinrich, M.B., Jeremiason, J.D., Brigham, M.E., Engstrom, D.R., Woodruff, L.G., Cannon, W.F., and Balogh, S.J Mercury in soils, lakes and fish in Voyageurs National Park (Minnesota): importance of atmospheric deposition and ecosystem factors. Environmental Science Technology 40: Wrenn, W.B. and Forsythe, T.D Effects of temperature on production and yield of juvenile walleyes in experimental ecosystems. Pp In: R.L. Kendall (ed). Selected coolwater fishes of North America. American Fisheries Society Special Publication 11.