© 2004 by CRC Press LLC section V Synthesis © 2004 by CRC Press LLC chapter seventeen Boreal Shield waters: models and management challenges* Robert J. Steedman Ontario Ministry of Natural Resources John M. Gunn Ontario Ministry of Natural Resources, Laurentian University Richard A. Ryder RAR and Associates Contents Glacial legacies A recent example of colonization Modern threats The challenge of integrative ecosystem indicators The challenge of ecosystem sustainability Acknowledgments References This book was designed to address two important questions related to the waters of the Boreal Shield:* (1) Can we effectively manage human interactions with Boreal Shield waters and aquatic biota, at local-to-global spatial scales, now and in the future? and (2) Can lessons from Boreal Shield waters and watersheds serve as useful models for other regions and ecosystems? Although human behavior has had great influence on Boreal Shield waters, we have limited ability to constructively affect these exquisitely complex and dynamic systems. Our influences, often harmful, have generally been through gross structural changes involving harvest or exploitation of ecological products and services such as fish, trees, hydraulic energy, and waste disposal. Our development practices also cause the insidious continued devastation of the shoreline ecotone, which serves as a center of attraction and * We used the Boreal Shield ecozone, the largest of the 15 ecozones in Canada, as the geographic focus of this book. Boreal or northern forest refers to the mainly coniferous forest that covers most of the northern portion of the ecozone. Shield refers to the exposed Precambrian Shield bedrock that extends across the entire ecozone (Ecological Stratification Working Group, 1995). © 2004 by CRC Press LLC production for many species of plants and wildlife. A sustainable relationship between humans and Boreal Shield waters therefore requires that we control and improve our environmental interactions and adopt a more cautious and protective role (i.e., the “pre- cautionary principle”). By adopting this principle, we recognize that we will often have to make choices from an array of potentially harmful actions, attempting to select the least harmful one. Glacial legacies In earlier chapters we introduced the idea that Salvelinus namaycush is a northern species pushed to southern latitudes by the glaciers, then stranded there in freshly gouged lake basins when the glaciers retreated, water levels declined, and the land began to rebound. We may infer that over time natural forces subsequently eliminated lake trout populations from some of those new habitats, particularly shallow, polymictic lakes; lakes with eroding shorelines and turbid waters; and lakes with high nutrient inputs, where competitors or predators such as walleye, northern pike, and bass became dominant. Now, 8,000 to 12,000 years later, we see three general types of lake trout lakes on the Shield. The first is a southern group of very large lakes, including a large portion of the Laurentian Great Lakes. In these massive, deep lakes, natural lake trout populations were vertically isolated from most competitors and predators, and were extremely abundant in all of these lakes until about 60 to 90 years ago. Availability of deep-water habitats in the Laurentian Great Lakes may also have favored the development of distinctive sympatric stocks or morphotypes. The second type is a group of intermediate-latitude lakes (i.e., boundary waters between Minnesota and Ontario, central and northern Ontario and southern Quebec) consisting of relatively shallow dimictic lakes (10 to 100 m) that generally provide well- oxygenated hypolimnia in the summer. The largest and deepest of these lakes often support diverse fish communities. In the shallowest of these lakes, lake trout populations are generally small and in constant jeopardy of exclusion by competing species and overharvesting by humans. The third type is a group of lakes north of the Boreal Shield ecozone (i.e., from northern Quebec and Labrador to Alaska) that includes several very large lakes, but also many small and shallow polymictic lakes where summer water temperatures are cool enough to support lake trout. Generally, fewer species exist in the most northerly lakes. A recent example of colonization Although derived from a relatively small geographic area, the recent findings from Sud- bury, Ontario serve to recapitulate and illustrate some of the postglacial lake trout history outlined above. Acid deposition from the Sudbury nickel smelters, the largest point source of SO 2 in the world in 1960, exterminated lake trout and many associated biota from nearly 100 lakes near Sudbury during the 1960s and early 1970s. Fortunately SO 2 emissions have been reduced by about 90% since 1960, resulting in water quality improvements in many former lake trout lakes (Gunn and Keller, 1990). Many lakes are still seriously damaged and further SO 2 reductions are required, but fishery rehabilitation projects have begun; preliminary results are both encouraging and illuminating (Gunn and Mills, 1998). For example, reestablishment of reproducing lake trout populations has proven to be very difficult in lakes with abundant competitors or predators (bass, walleye, whitefish, etc.), but almost routine in lakes with relatively simple fish communities (Hitchins and Samis, 1986; Gunn et al., 1987; Evans and Olver, 1995). The availability of spawning sites does © 2004 by CRC Press LLC not appear to be a limiting factor in these recovering lakes or for that matter in most other Shield lakes; newly established populations appear to quickly find enough suitable sub- strate sites for egg deposition (Gunn, 1995). When lake trout are restocked in very warm shallow lakes, the fish die in years with particularly warm summers (Gunn, 2002). When the watersheds of former lake trout lakes are heavily urbanized and the lakes are polluted by nutrient-rich stormwater runoff, oxygen levels decline in deep water habitats, spawning shoals are fouled with attached algae, reproduction is lost, and recolonization fails. When angling harvest is uncontrolled and excessive, lake trout populations are jeopardized as well (Gunn and Sein, 2000). Modern threats These histories and our recent observations suggest that lake trout face four major threats in the 21st century (Loftus and Regier, 1972; Evans et al., 1991; Ryder and Orendorff, 1999): 1. Overexploitation (lakes are relatively unproductive; fish are easy to catch) 2. Cultural eutrophication (loss of suitable hypolimnetic and reproductive habitat) 3. Introduction of invasive species (often via bait buckets) 4. Climate warming (lake trout in small, shallow lakes in northern areas are vulner- able to increased summer water temperatures; warm-water competitors increase in abundance) The challenge of integrative ecosystem indicators Lake trout become large, long-lived, and both ecologically and commercially valuable top predators in healthy environments. As such they have attracted great interest as integrative indicators of the health of Shield catchments and atmospheric conditions (Maitland et al., 1981; Ryder and Edwards, 1985; Marshall et al., 1987). The existence of robust, high-quality native lake trout populations clearly tells us that something is right about the biosphere in general and Boreal Shield waters in particular. For example, where lake trout thrive we may infer that the various physical, chemical, and cultural stressors identified in Table 17.1 and emphasized throughout this book are inactive, active at low levels, or active but recent. Where lake trout are declining or threatened, we may conclude that chronic or unsustain- able stresses are active. Human activity influences forests and waters directly and indirectly over large and small spatial scales (Table 17.1). There is considerable variation in the quality of scientific understanding about these influences, and as might be expected, large-scale impacts tend to be associated with greater uncertainty. Complex, multiscale threats to lake trout waters are difficult to identify, quantify, predict, and mitigate. For this reason, managers and researchers have explored integrative surrogate indicators, such as lake trout, capable of providing diagnostic, quantitative, advance warning of impending degradation of Shield ecosystems. This evolution was spurred in part by regulatory guidelines that specified protection of “biotic integrity” as required by the 1972 U.S. Federal Water Pollution Control (“Clean Water”) Act, the 1978 Great Lakes Water Quality Agreement, and the Canadian National Parks Act. Although a wide range of physical, chemical, and biotic indicators have been proposed for ecosystems, few have been implemented by management agencies. Unfortunately, the problems associated with finding practical, affordable, and technically unambiguous indi- ces still appear rather intractable. Nonetheless, the scientific studies and debates associated with these various initiatives have greatly increased our knowledge and our recognition of the complexity of these ecosystems (Ryder and Orendorff, 1999). © 2004 by CRC Press LLC Table 17.1 Spatial Scale of Human Impacts on Boreal Shield Waters Spatial Scale Strength of Available EvidenceStressor Lake Catchment Regional to Global Examples of Possible Impacts Notes 1. Climate change X Loss of cold-water habitats, expansion of cool- and warm-water species Weak to moderate Refers to recent climate impacts caused by human activity 2. Long-range atmospheric transport and deposition of pollutants X Acidification of water and soil, local extinction of aquatic biota, bioaccumulation of mercury and persistent organic contaminants Good 3. Ozone depletion X Cellular, genetic damage from UV-B radiation, biotic impairment Weak Strong potential interaction with Stressors 1 and 4 via dissolved organic carbon and water transparency 4. Non-point-source land use and forest disturbance X Mild to severe nutrient enrichment and hypolimnetic oxygen depletion, contamination, biotic impairment Good Relative impacts: urbanization > agriculture > forestry, wildfire 5. Introduced species X X Behavioral and niche shifts, decreased production Good Introduction, e.g., of centrarchid fishes 6. Point-source discharges X X Mild to severe nutrient enrichment and hypolimnetic oxygen depletion, contamination, behavioral changes, biotic impairment, local extinction Good Effluent from, e.g., pulp mills, mine tailings ponds, municipal sewage treatment plants; includes discharge of heated water from thermal power plants 7. Impoundment, dewatering, or diversion X X Seasonal dewatering of spawning habitat, impaired reproduction, local mercury methylation Good Depends on water regulation regime 8. Shoreline or basin modification X Loss of habitat, impaired reproduction, nutrient loading, burial of lake or stream Good For instance, road construction, mines or tailing ponds, cottage development; includes impacts described in Stressor 4 9. Angling X Direct mortality, demographic change, local extinction Good Depends on harvest management Source: After Regier (1979) and various chapters in this book. © 2004 by CRC Press LLC For the last 50 to 80 years researchers have used Shield lakes as models in their studies of aquatic ecosystem response to disruption by human activities. As a result, many human effects on Shield waters are well documented and are at least partially predictable in an empirical or qualitative sense (Table 17.2). Many of these studies highlight the importance of catchment morphology and disturbance regimes and confirm the importance of long- term monitoring, comparative studies, and ecosystem experiments. A major challenge that remains is the need to develop useful diagnostic information when confronted with multiple stressor interactions. We now recognize that ecosystems are typically influenced simultaneously by multiple stressors, each potentially associated with quite similar responses from lake trout populations (Rapport et al., 1985). Lake trout may for instance be simultaneously subjected to harvest, habitat disruption, persistent contaminants, and introduction of exotic aquatic species. All of these stresses may contribute in part to a reduction in lake trout reproductive success and ultimate population size (Evans et al., 1991). The science summarized in Table 17.2 spans spatial scales from local to biospheric (global). Model outputs (e.g., descriptions such as those that deal with thermal structure, water chemistry, composition of biotic assemblages, and lake trout demographics are but four examples) may be useful in some contexts as direct indicators of lake trophic status or as surrogates of large-scale (e.g., ecozone or landscape) phenomena. The most quanti- tative models tend to be regional in scope and relevant primarily to water yield and water quality rather than to habitat and biota (Carignan and Steedman, 2000). Some of these models (e.g., Ryder, 1965; Dillon and Rigler, 1975) have been used at various times as formal regulatory or assessment tools. Some recent findings suggest that lake trout lakes may be less responsive to certain types of watershed disturbances than previously thought. Water renewal times for deep Shield lakes, where lake volume is large relative to catchment area, may range from a decade or so for small headwater lakes, to a century or more in the case of Lake Superior. This combination of lake morphology and drainage position creates significant hydrologic, thermal, and chemical inertia that may protect lake trout lakes to some degree. For example, temporary catchment disturbances that alter runoff hydrology or chemistry typically exert only small annual influences on lake trout lakes, and these effects may dissipate before the lake responds significantly (Schindler et al., 1980; Carignan et al., 2000; Steedman, 2000). In contrast, the serious consequences of chronic watershed disturbance have been repeatedly and thoroughly documented (in this volume, Legault et al. [Chapter 5], Driscoll et al. [Chapter 10], Krueger [Chapter 10], Steedman et al. [Chapter 4]). Slow water renewal rates may also delay the recovery of lakes from contaminant spills (also airborne contaminants) and can also increase the exposure and breakdown of DOC (dis- solved organic carbon), leading to increased clarity and deeper penetration of solar radi- ation, including ultraviolet (UV) radiation (Schindler et al., 1997) Boreal Shield ecosystems are among the best-studied natural ecosystems on earth, especially from a hydrological and geochemical perspective. However, there are still many challenging research questions to pursue, particularly when we try to understand the links between the physical and the biotic components. For example, Boreal Shield ecosystems are effective at collecting persistent organic pollutants (POPs) on the waxy surfaces of coniferous trees (Wania and McLachlan, 2001). However, the chronic effects of these trace contaminants on the biota are poorly understood. So, too, and perhaps more surprising, is the lack of quantitative information on the role of the littoral zone in the productivity and energy dynamics on Boreal Shield lakes. In fact, ecologists are just beginning to describe the community composition of some of the dominant species in the littoral zone, such as the species-rich microcrustaceans (Walseng et al., 2003). Important ecological events such as the annual ice melt (Figure 17.1), which may trigger and structure much © 2004 by CRC Press LLC Table 17.2 Science Relevant to Conceptual and Quantitative Models of Boreal Shield Aquatic Ecosystem Response to Disturbance Spatial Scale Spatial Integration (km 2 ) Environmental Context Model Name (if Applicable) Inputs (Landscape or Environment Drivers) Outputs (Lake-Scale Attributes or Indicators) Primary References Global to regional 1,000–10,000 Anthropogenic climate change, long- range transport of atmospheric pollutants, ozone depletion Average annual temperature, land cover, precipitation Various physical and biological attributes of lakes (ice cover duration, water renewal times, dissolved organic carbon, airborne contaminants in biota) Magnuson et al. (1990); Schindler et al. (1990, 1996); Shuter and Meisner (1992); Yan et al. (1996); Snucins and Gunn (1995); Schindler (1998, this volume) 1–1,000 Biogeography and biodiversity: distribution of fish species Lake area, latitude, biogeography Fish species richness and community composition Matuszek and Beggs (1988); Matuszek et al. (1990); Minns (1989) Lake morphometry, productivity, pH, alkalinity, conductivity Lake trout presence Conlon et al. (1992); Gunn and Keller (1990); Ryan and Marshall (1994); Driscoll et al. (Chapter 10, this volume); Mills et al. (2000) Watershed 1–1,000 Cumulative hydrologic impacts Catchment forest disturbance, terrain model Water yield, extreme flows Buttle and Metcalfe 2000; Buttle et al. (2000) Material exports from land (water, carbon, nutrients, forest litter, sediment) Ontario Trophic Status and refinements Lake P budget (from catchment geology and land use, aerial deposition, sedimentation) Water clarity (chlorophyll and Secchi depth) Dillon and Rigler (1975); Hutchinson et al. (1991); Dillon et al. (1991, Chapter 7, this volume); Beaty (1994); Bayley et al. (1992); Snucins and Gunn (2000) © 2004 by CRC Press LLC Water quality in lakes with burned and logged catchments Catchment disturbance, lake morphology Concentration of dissolved nutrients, carbon, cations Carignan et al. 2000; Steedman (2000); Knapp et al. (2003); Lake morphometry, catchment morphometry, and drainage patterns Concentration of dissolved organic carbon Rasmussen et al. (1989); Schindler et al. (1997); Molot and Dillon (1997) Ontario end-of- summer oxygen profile Lake morphometry, total phosphorus, dissolved oxygen at spring turnover Late summer dissolved oxygen profile Molot et al. (1992); Clark et al. (Chapter 6, this volume) Mercury accumulation in aquatic biota Watershed slope, forest disturbance, reservoir age, lake and watershed morphology, fish species and size, sediment characteristics Mercury concentration in zooplankton and fish Garcia and Carignan (1999, 2000); Bodaly et al. (1984), Chapter 9, this volume; Jackson (1991); McMurtry et al. (1989); Legault et al. (this volume) Lake 1–100 Benchmark expectations for fish production Morphoedaphic index (MEI) and refinements Mean lake depth, total dissolved solids, thermal habitat volume Long-term commercial fishery harvest (large lakes) Ryder (1965, 1982); Christie and Regier (1988); Shuter et al. (1998) Effects of angling, introductions of exotic species Lake morphometry, temperature profiles, angler effort and harvest, age-structured mortality and growth rates Maximum sustained yield, allowable yield; production, structure, and dynamics of lake trout populations Payne et al. (1990); Shuter et al. (1998); in this volume, Lester and Dunlop, Chapter 16, Vander Zanden et al.; Chapter 13, Gunn and Sein (2000) Shoreline disturbance Shoreline disturbance by logging and wildfire Whole-lake and littoral water temperature Steedman and Kushneriuk (2000); Steedman et al. (1998, 2001) Littoral sedimentation Steedman and France (2000) Littoral fish populations Steedman (2003) © 2004 by CRC Press LLC of what happens biologically for the rest of the season, have not been thoroughly studied. The role of UV radiation and PAR (photosynthetically active radiation) in habitat use, the use of thermal refuge areas, the impact of invasive species, the effect of climate warming on lake productivity … the research challenges, both old and new, remain. The challenge of ecosystem sustainability Given the high frequency of fire and insect outbreaks in the boreal forests and the glacial history of this region, Shield ecosystems may seem quite resilient. It is not known what these ecosystems were like in the interglacial periods, but it is probably safe to assume that each time the “slate was wiped clean” due to glacial action, functional ecosystems reestablished themselves. The individual Shield ecosystems seen today are therefore only one part of a temporal series of ecosystems that existed at this site, and the present conditions are in fact quite young in geological time, from a few decades or centuries to at most 12,000 years. The soils are also young, an interesting feature that Wright (2001) considered important in the high resilience of glaciated areas from the impacts of air pollutants (SO 2 ). In catchments lacking this glacial history, soils are older, and sulfur is strongly absorbed to iron and aluminum sesquioxides, making these nonglaciated systems slow to recover. The terrestrial flora and fauna of Boreal Shield ecosystems have many well-known adaptations to disturbances such as fire, but the aquatic biota also exhibit many specialized adaptations to changing conditions. For example, many zooplankton have resting stages that can remain dormant for decades or centuries until conditions improve (Hairston et al., 1995). Fish migration also occurs among connected lakes, often with surprising ease for some species (Jackson et al., 2001). Boreal Shield ecosystems may therefore prove to be more adaptable to changing conditions than we might have originally expected, but one aspect of their identity appears unchangeable: they contain relatively low-productivity waters. Attempts to increase lake trout production by modifying habitat features (such as creating or cleaning spawning sites) are therefore destined to fail. Unfortunately, hundreds of these so-called enhance- ment projects have been conducted in lakes where the real management problem is Figure 17.1 Spring thaw. Climate models suggest that the ice-free season will be much longer in the future. (Photo by V. Liimatainen.) © 2004 by CRC Press LLC excessive lake trout harvest, cultural eutrophication, or the impact of introduced species. Some people may argue that such habitat enhancement projects are still useful because they encourage public involvement in fisheries management and conservation. However, ineffective habitat enhancement projects more likely simply delay development of science and policy addressing the real problems and discourage the well-intentioned volunteers when they see that nothing comes of their efforts. The inherently limited productivity of Shield waters also constrains the usefulness of other management actions such as hatchery stocking. Stocking may be necessary for rehabilitation purposes when a particular species has been extirpated from a lake, but when used in an attempt to supplement depressed natural populations it can often do more harm than good (Evans and Willox, 1991). For example, it can create highly unreal- istic public expectations and thus increase fishing pressure to the point that irreplaceable remnant stocks of native fish are lost along with the introduced fish. Genetic introgression and disease transmission may be additional undesirable side effects of inappropriate stocking efforts (Powell and Carl, Chapter 12, this volume). Rather than focus on how more lake trout can be produced, our desire should be to raise the value of the lake trout we have (Figure 17.2). One way to do this is to celebrate their role as environmental sentinels. What we are suggesting here is that the lake trout can be the “miner’s canary” of Boreal Shield lakes, a species with narrow environmental tolerances (stenoecious species) that can serve as an early-warning signal for the ecosys- tem. As the largest and longest lived of the salmonid fishes native to the Shield, the lake trout also provides a longer term record because it carries within its body a physical and chemical history of the Boreal Shield environment (Figure 17.3). One of the most compel- ling of these stored signals is mercury body burden (Figure 17.4), which in recent years has been recognized as significantly affected by long-range atmospheric transport and deposition of fossil fuel emissions that originate far beyond Boreal Shield watersheds. Lake trout in many lakes exceed mercury consumption guidelines, even in the absence of local watershed disturbance. Due to its preference for deep, clear lakes, the lake trout is not always the most contaminated fish species (i.e., see walleye in Figure 17.4) in Boreal Shield waters. However, this does not mitigate the fact that distant human activity has polluted hundreds of lake trout lakes and other Boreal Shield lakes via this mechanism. If we look ahead 100 or perhaps 500 years into the future, there is no doubt that lake trout ecosystems of the Boreal Shield will still be highly valued by humans but perhaps for different reasons. In future centuries urbanization and other demographic changes (e.g., depopulation of many northern towns) will likely continue, and participation levels in fishing and hunting may decline, but humans will no doubt still passionately value this landscape. The value of Boreal Shield ecosystems as sources of nutritious food will likely remain, and the importance of these ecosystems for clean drinking water, energy, and fiber will likely increase enormously, as will their value for recreation, art, and escape from the hectic urban life. The fact that we cannot imagine what this future will be simply reinforces the need to implement effective monitoring and conservation programs now to help protect this landscape. Finally, it needs to be recognized that the often-repeated comment that the “fishing is not as good as it used to be” is not just a memory lapse. Overfishing and habitat degradation have occurred (Post et al., 2002), invading species (including humans) have arrived from all over the world, and climate changes are occurring with unknown effects (Schindler, 1998). Boreal Shield ecosystems are not static and in many ways may not be considered particularly fragile, but they need proactive and adaptive protection now. We cannot expect to “manage” these ecosystems in the same way or with the same control that we might try to manage a business. However, new information about the most important, tractable problems can be used to develop a healthier and more sustainable [...]... central Ontario about 50 km north of Sault Ste Marie It is an undeveloped and completely forested headwater basin with an area of 10.5 km2; it contains a chain of four lakes (five distinct lake basins) that ultimately drain into Lake Superior via the Batchawana River (Figure A1 .2) Comprehensive records of meteorological and surface water physical and chemical data have been maintained from the study’s inception... Molot, L .A. , 2003, Lake trout (Salvelinus namaycush) habitat volumes and boundaries in Canadian Shield lakes, in Boreal Shield Watersheds: Lake Trout Ecosystems in a Changing Environment, Gunn, J.M., Steedman, R.J., and Ryder, R .A. , Eds., Lewis Publishers, Boca Raton, FL, Chap 6 Conlon, M., Gunn, J.M., and Morris, J.R., 1992, Prediction of lake trout (Salvelinus namaycush) presence in low-alkalinity lakes... Long-term monitoring programs are essential to identify the rate and direction of environmental change in the Boreal Shield ecozone Canada’s Ecological Monitoring and Assessment Network (EMAN; www.eman-rese.ca) currently provides a coordinating service to support data sharing, communication, and training in environmental and ecological monitoring and to assist in preparing state-of-the-resource assessment... Laurentian Great Lakes and 33 other large lakes (>10,000 ha), many of which cross jurisdictions, are not included Alternate names are listed in parentheses, and a separate entry is given for each name Lakes with the same name are ordered by latitude This atlas is considered an accurate list of lake trout lakes in these jurisdictions at the time of publication; however many other lake trout lakes may be... discovered in the future, particularly in parts of Quebec where less extensive surveys have been conducted In addition, other lake trout lakes exist in the Shield bedrock regions of Alberta, Manitoba, Michigan, Saskatchewan, and Wisconsin These areas are part of the Boreal Shield ecozone, but these lakes are not yet included in the atlas Lake names and descriptions were obtained from lake management agencies... northeastern Ontario, Canadian Journal of Fisheries and Aquatic Sciences, 57(Suppl 2): 5–18 Carignan, R., D’Arcy, P., and Lamontagne, S., 2000, Comparative impacts of fire and forest harvesting on water quality in Boreal Shield lakes, Canadian Journal of Fisheries and Aquatic Sciences, 57(Suppl 2): 105– 117 Carignan, R and Steedman, R.J., 2000, Impacts of major watershed perturbations on aquatic ecosystems. .. North America’s limnological pioneers With long-term predictive regional ecology as the focus, intensive data collection began on seven LTER lakes in 1981 and continues More information on the lakes, current research, and online data catalogue is available at http://limnosun.limnology.wisc.edu/ Sudbury area lakes Monitoring of lakes in the Sudbury, Ontario, area (Figure A1 .5) began in the early 1970s, and... of Biological Indicators of Ecosystem Quality in the Great Lakes Basin, Report to the Great Lakes Science Advisory Board of the International Joint Commission, Windsor, Ontario Ryder, R .A and Orendorff, J .A. , 1999, Embracing biodiversity in the Great Lakes ecosystem, in Great Lakes Fisheries Policy and Management: A Binational Perspective, Taylor, W.W and Ferreri, C.P., Eds., Michigan State University... Ecozone, Indicators and Assessment Office, Environment Canada, Ottawa Available online at www.ec.gc.ca/soer-ree/english/default.cfm © 2004 by CRC Press LLC appendix two Lake trout lakes of the Boreal Shield ecozone of North America Lake trout lakes are listed alphabetically for the jurisdictions of Minnesota, New York (Adirondacks), Ontario (Northeastern, Northwestern, South Central) and Quebec The Laurentian... Ontario approximately 250 km from Winnipeg and 50 km east-southeast of Kenora The ELA includes 58 small lakes (with areas 1 to 84 ha) and their drainage basins, plus three additional stream segments set aside and managed through an agreement between the Canadian and Ontario governments For an additional description of the site see the ELA special issue of the Journal of the Fisheries Research Board . and Molot, L .A. , 2003, Lake trout (Salvelinus namaycush) habitat volumes and boundaries in Canadian Shield lakes, in Boreal Shield Watersheds: Lake Trout Ecosystems in a Changing Environment, . currently provides a coordinating ser- vice to support data sharing, communication, and training in environmental and ecological monitoring and to assist in preparing state-of-the-resource assessment. managers and researchers have explored integrative surrogate indicators, such as lake trout, capable of providing diagnostic, quantitative, advance warning of impending degradation of Shield ecosystems.