5
Addressing the Threats to Atlantic Salmon in Maine

A STRATEGY FOR CONSERVATION AND RESTORATION

The complex and dynamic nature of terrestrial, aquatic, and marine ecosystems makes conservation and restoration—especially of threatened and endangered species—a daunting task. Because water connects all three ecosystem types to each other and to Atlantic salmon, to other organisms, and to people, watersheds become the logical unit for an ecosystem approach to conservation and restoration.

The 1997 Conservation Plan (Maine Atlantic Salmon Task Force 1997) provides the foundation for wide range of current efforts in Maine. It describes threats and associated mitigation or management options. Like any plan, it can be improved with the benefit of 5 years of intensive research and operational experience in Maine as well as information from other parts of the world. Principally, it would be improved by more clearly prioritizing, sequencing, and coordinating plans and actions in an adaptive management framework. This means every activity is a field experiment that generates data, information, and experience while sustained progress is made toward conservation and restoration goals. A well-documented cycle of planning, implementation, performance monitoring, and subsequent adjustment or refinement is used to rapidly converge on optimal solutions and methods. Pairing an untreated area, stream reach, or watershed as a reference condition (to account for the complex influences of natural variation) with a similar site where a management action is applied, yields timely information about overall effectiveness (both eco-



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Atlantic Salmon in Maine 5 Addressing the Threats to Atlantic Salmon in Maine A STRATEGY FOR CONSERVATION AND RESTORATION The complex and dynamic nature of terrestrial, aquatic, and marine ecosystems makes conservation and restoration—especially of threatened and endangered species—a daunting task. Because water connects all three ecosystem types to each other and to Atlantic salmon, to other organisms, and to people, watersheds become the logical unit for an ecosystem approach to conservation and restoration. The 1997 Conservation Plan (Maine Atlantic Salmon Task Force 1997) provides the foundation for wide range of current efforts in Maine. It describes threats and associated mitigation or management options. Like any plan, it can be improved with the benefit of 5 years of intensive research and operational experience in Maine as well as information from other parts of the world. Principally, it would be improved by more clearly prioritizing, sequencing, and coordinating plans and actions in an adaptive management framework. This means every activity is a field experiment that generates data, information, and experience while sustained progress is made toward conservation and restoration goals. A well-documented cycle of planning, implementation, performance monitoring, and subsequent adjustment or refinement is used to rapidly converge on optimal solutions and methods. Pairing an untreated area, stream reach, or watershed as a reference condition (to account for the complex influences of natural variation) with a similar site where a management action is applied, yields timely information about overall effectiveness (both eco-

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Atlantic Salmon in Maine logical and economic). Replicated across several sites, the scientific method supplants well-intentioned trial and error as an efficient and systematic way of improving conservation and restoration efforts. The following sections deal in more detail with specific threats. DAMS As described in Chapter 3, dams block passage and later riverine environments both below and above them. Mitigating the threat they pose is usually most completely achieved by removing them, but enhancing passage alone can be at least somewhat effective if they affect only short stretches of river. Mitigating their effects has been discussed in more detail in NRC (1996a) and Heinz Center (2002). The decision analysis example on enhancing habitat in Chapter 4 and the discussion of the costs of dam removal at the end of this chapter provide additional information on addressing the threats to dams, as does the summary of the 1997 Conservation Plan (Maine Atlantic Salmon Task Force 1997) toward the end of this chapter. HATCHERIES Possible Goals for Hatcheries At this stage in the decline of wild populations of Atlantic salmon in the state of Maine, the goals of hatcheries need to be explicit. The recent steep declines in salmon numbers, in spite of increases in hatchery production and the very recent change to river-specific stocking, mean that efforts need to be concentrated on rebuilding wild populations in Maine’s rivers. It is helpful to specify immediate goals aimed at dealing with the current extinction crisis as well as ongoing goals that would continue to apply even as signs of rebuilding are seen. It would also be helpful to adapt earlier assumptions and goals to current conditions and scientific knowledge. Immediate Goals The goal of hatcheries in response to the extinction crises in Maine should be to conserve genetic quality—a broad term that includes the concepts of genes adapted to local conditions, complementary and coadapted genes, and appropriate genetic diversity—in the remaining wild populations of Atlantic salmon, allowing these survivors to persist. In this respect, the hatcheries might serve as living gene banks. The operation of the Craig Brook National Fish Hatchery is compatible in part with this

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Atlantic Salmon in Maine goal. The large Craig Brook National Fish Hatchery could be altered to fill this role, but it is currently a production hatchery for several stocks separated by natal river. Therefore, changes would be needed in its functioning. Less effort to produce large quantities of releasable fry should make at least some facilities available for careful management of limited brood stock. In addition, some effort could be redirected to working with scientists to address research questions that have already been raised as well as new ones that will emerge as the project proceeds. The most urgent goal is to preserve the genetic structure of the remaining populations, while the longer-term processes of habitat expansion and rehabilitation are pursued. An equally pressing goal should be the acquisition of basic information and research needed to ensure at least two return spawners for each spawning female in the wild. Ongoing Goals The ongoing goals of hatcheries should include the preservation of technical knowledge and public education about the biology and ecology of salmon in the wild. The successful production biologists at hatcheries acquire the skill of culturing Atlantic salmon. The skill cannot be fully communicated in technical reports, because it depends on experience and is best taught by practitioners. This skill must be maintained. Many people are fascinated by hatcheries. Hatcheries should be more integrated into public education and designed for site visits. Atlantic salmon have long been an icon for environmental awareness. Resources should be directed toward adaptive management studies, allowing managers to put research findings into evolving practice in a timely fashion. In the short term, there is a need to better understand how genetic, ecological, and physiological processes affect the ability of hatchery-released fish to survive and successfully reproduce in rivers of Maine, compared with naturally reproduced fish. Unclear Goals The goal of providing enough fish to support the commercial or recreational fishery, if such a goal is still imagined, is not clearly articulated. Efforts to subsidize the fishery have been unsuccessful thus far, although fisheries for anadromous salmonids have been subsidized with varying degrees of success through hatchery production elsewhere in North America and other countries. Clearly, current hatchery operations in Maine cannot support recreational or commercial fisheries for anadromous Atlantic salmon. It is possible to establish a small recreational fishery for salmon by rearing fish to adulthood in a hatchery and then releas-

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Atlantic Salmon in Maine ing them into rivers, but that would not satisfy the Endangered Species Act (ESA) or the stated goals of Maine and federal officials to establish wild salmon populations. If salmon runs in Maine were restored to their pre-dam sizes (before about 1750), they would probably support both recreational and commercial fishing, especially if they were carefully regulated. It is outside the committee’s charge to consider other goals than salmon rehabilitation in Maine’s rivers, but we have heard comments suggesting that other fish species should be stocked in them if neither recreational nor commercial fishing for salmon can ever be expected. Reducing Threats Posed by Hatchery Programs In pursuing the immediate and ongoing goals listed above, it is critically important to consider the growing evidence of genetic and ecological threats posed by hatchery programs. Whenever managers decide to include hatcheries as part of a broader recovery strategy, they need to prevent or reduce those threats through application of practices designed to adhere to “best-practice” genetic, evolutionary, and ecological principles (Miller and Kapuscinski 2002). Although many of the protocols currently used reflect best practices, a more comprehensive vision of how to use hatcheries as part of a program of protection and rehabilitation is needed. That includes recognition of adverse effects that hatcheries can have on the genetic makeup of salmon population, both those than can be reduced by careful practice and those that cannot. The genetic makeup and phenotypic traits of hatchery-propagated salmonids often differ from those of the wild populations that they are meant to rehabilitate and with which they will interact. Hatchery fish phenotypes commonly differ in ways that will influence ecological interactions between them and wild fish. A meta-analysis of hatchery effects on pre-spawning behavior shows strongly that hatchery rearing results in increased pre-adult aggression and decreased response to predators that may, in part, explain their decreased subsequent survival in the wild (in 15 of 16 case studies) (Einum and Fleming 2001). Somewhat less frequently, hatchery salmonids show changes in growth rates, migration and feeding behaviors, habitat use, and morphology, as reviewed below. Recent evidence of a genetic basis for resistance to pathogens, also as reviewed below, suggests that hatchery programs can inadvertently reduce the genetic quality needed for disease resistance. Genetic Hazards Hatcheries used to rehabilitate depressed populations can impose a variety of genetic hazards. Extinction is the extreme hazard from which

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Atlantic Salmon in Maine recovery is impossible. The other hazards are all a form of degradation of what is called genetic quality. Genetic quality refers to the overall quality of the genotypes in the population in terms of their effect on the ability of fish to survive, thrive, and respond to changes in their natural environments. (It assumes that the natural environment itself has not been so degraded that it cannot support the populations.) Genetic quality includes individually “good” genes, which confer fitness to individuals that possess them; compatible and co-adapted genes, which provide superior fitness through their complementation of genes at other loci (Andersson 1994, Carrington et al. 1999, Penn and Potts 1999); and appropriate genetic diversity, which confers evolutionary potential by allowing for a variety of genotypes to be produced from various matings but does not counteract other aspects of genetic quality. For example, domestication selection is a well-known hazard of supportive breeding programs (Fleming and Gross 1989; McGinnity et al. 2003; NRC 1996a; Reisenbichler 1997; Waples 1991a, 1999). Domestication selection is a form of degradation of genetic quality by reducing the fitness of hatchery fish in their natural environment. Many aspects of hatchery programs (supportive breeding) can affect genetic quality. For example, in nature, breeding is not random with respect to genetics (Andersson 1994). By making pair matings or even using other protocols, hatcheries usually limit or work against sexual selection (mate choice) and life-history decisions that help to maintain genetic quality in natural populations (Fleming and Gross 1989, Grahn et al. 1998, Wedekind 2002). Sexual selection can increase fitness by increasing the viability of offspring (Møller and Alatalo 1999). Hatchery protocols typically select against precocious males (e.g., jacks in Pacific salmon and mature parr and grilse in Atlantic salmon), which contribute to genetic quality (Gross 1996; Gross and Repka 1998a,b). Thus, maximizing genetic diversity by preventing mate choice might not be an effective conservation strategy (Wedekind 2002). Some of the components of genetic quality and the ways that they can be degraded in hatcheries are discussed below. There is increasing documentation of the empirical reality of these genetic hazards (Kapuscinski and Brister 2001, McGinnity et al. 2003, Miller and Kapuscinski 2002, Shaklee and Currens 2002). Hatchery managers can somewhat reduce these risks and can totally avoid certain others by applying appropriate genetic guidelines (Miller and Kapuscinski 2002). Current protocols in place at the Craig Brook hatchery for river-specific supportive breeding of distinct population segment (DPS) brood stocks generally adhere to current guidelines for reducing or avoiding some genetic hazards. Current practices that raise residual concerns are discussed in some detail below. Further information is available elsewhere (Miller and Kapuscinski 2002

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Atlantic Salmon in Maine and references therein). It is impossible to avoid degrading all aspects of genetic quality at the same time in a hatchery. The committee reiterates that avoiding extinction probably should take priority over all of the other genetic considerations. Extinction Demographic processes in the hatchery program can cause extinction under certain conditions. An extreme example would be a hatchery catastrophe in which an entire population of fish brought into captivity is killed. In addition, genetic processes in the hatchery can contribute to extinction risk in subtler ways, as suggested by recent studies attributing increased rates of extinction to reduced levels of genetic variability (Newman and Pilson 1997, Saccheri et al. 1998). The current DPS-river supportive breeding and propagation program at the Craig Brook hatchery reduces the risk of purely demographic extinction by bringing only a portion of a river’s parr or returning adults into captivity (Buckley 2002a,b). Additional analyses of extinction risk are being developed with the aim of including them in the Recovery Plan (USASAC 2003). There is a trade-off between leaving the whole population together and splitting it, however. Splitting an already small population into wild-and captive-reproductive subunits simultaneously increases the risk of losing genetic variability within one or both subpopulations, as discussed in the next section. For example, as run sizes in the Penobscot have declined over the last decade, collections of adults for hatchery breeding have progressively become a greater fraction of the adult returns. Specifically, females spawned in the hatchery rose from 17% of all returning MSW adults in 1986 to 86% in 1998 (K.F. Beland, Maine Atlantic Salmon Commission, unpublished data, 2003), and adults of both sexes collected for hatchery spawning made up over 60% of all returning adults in 2000 and 2001 (Buckley 2002a), up from 17% in 1986. This trend increases the overall exposure of the Penobscot population to loss of genetic quality. The current supportive breeding program for the six DPS rivers (all except the Ducktrap River and Cove Brook) and the hatchery propagation of Penobscot fish minimizes the extinction risk due to loss of genetic variability by including one-on-one matings and tracking contributions of each family to fry releases and adult returns via genetic markers (Buckley 2002a). However, it does not eliminate loss of genetic quality. By overriding mate selection and perhaps by sampling error, it reduces the likelihood of genetic complementation. For example, the major histocompatibility complex (MHC) is involved in disease resistance (see e.g., Arkush et al. 2002), and one-on-one matings probably reduce genetic complemen-

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Atlantic Salmon in Maine tation at that complex of genes and thus reduce genetic resistance to disease. Loss of Within-Population Genetic Variability Loss of within-population genetic variation has several causes, the most important of which is genetic drift due to sampling gametes in finite populations. Loss of genetic variation due to drift occurs at a rate inversely proportional to the genetically effective population size (Ne). The Ne refers to the size of an “ideal” population that has the same rate of loss of heterozygosity (a common measure of genetic variation) as the actual population has, the “ideal” population being defined on the basis of demographic characteristics such as an even sex ratio, stable population size, no immigration, and a Poisson distribution of progeny number. Estimates of Ne for populations of salmonids have typically been smaller than the actual number of reproducing adults, ranging between 4% and 73% of the number of reproductive adults (Ardren and Kapuscinski 2003, Bartley et al. 1992, Heath et al. 2002). In a process known as the extinction vortex (Gilpin and Soulé 1986), inbreeding and loss of genetic variability due to genetic drift can result in reduced fitness. This loss of fitness may reduce Ne, resulting in greater inbreeding and further loss of variability, which reduces fitness further. The continuing reduction in population size exposes the population to ever-increasing demographic risk of extinction. Considerable interest has been devoted to the threats to wild and captive populations associated with inbreeding and loss of genetic variability, and much of this work refers directly to fishes in general, and salmonids in particular (Allendorf and Phelps 1980; Allendorf and Ryman 1987; Cross and King 1983; Ryman and Ståhl 1980; Ståhl 1983, 1987; Waples 1991a). Loss of within-population genetic variability is the most common hazard associated with decisions regarding numbers of adults in the hatchery to be mated and how they are to be mated. For instance, the high fecundity of salmon fosters a temptation to produce large numbers of progeny from a few parental fish in each breeding season, artificially creating a “genetic bottleneck” that significantly reduces genetic variability among the progeny. Current protocols at the Craig Brook hatchery for DPS river brood stocks appropriately avoid this obvious pitfall (Buckley 2002a,b). Those protocols include collecting enough parr or adults to ensure reasonable numbers of reproducing adults, one-on-one matings to ensure that each adult contributes, application of genetic profiles to avoid mating close relatives, and use of genetic markers to track families of DPS fish through the hatchery and beyond. Appropriate features of hatchery mating of Penobscot adults include the one-on-one mating design and the

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Atlantic Salmon in Maine collection of genetic data that can be analyzed to avoid matings of close relatives, although the latter is less crucial for this larger population (compared to DPS captive brood stock) and does not appear to have been carried out as of 2002 (Buckley 2002a). Loss of Genetic Variability from Supportive Breeding Supportive breeding, as defined above, augments Ne for the hatchery component of the population, but it also entails a potential risk of increasing the loss of within-population genetic variability in the wild. When supportive breeding meets its intended rebuilding goal, it increases the total population size through a higher reproductive output from the captive breeders than from those reproducing in the wild. That increases the reproductive success of the captive (hatchery) segment of the population relative to that of the wild segment of the population. The resulting large increase in the variance of family size within the total population (wild plus captive) is sufficient to reduce the effective population size as a whole (Ryman and Laikre 1991, Ryman 1994, Ryman et al. 1995b, Wang and Ryman 2001). See Appendix C for a detailed discussion of this problem. Often, an overall reduction of effective size cannot be avoided when applying supportive breeding that successfully increases the population census size. However, that problem may not be overly important in the case of declining populations, such as the severely depleted salmon populations in Maine, for which supportive breeding may yield a higher Ne value than would occur in its absence. Most Atlantic salmon populations in Maine are severely depleted and continue to decline, and for such populations, the positive effects of increasing the actual population size outweighs the potential short-term genetic drawbacks caused by reductions of the Ne. Thus, the need for supportive breeding is urgent. However, no extensive analysis has been done on the genetic impact of supportive breeding on populations that would continue to decline if left on their own (but see Duchesne and Bernatchez [2002] for the special case of binomially distributed family sizes). Clearly, in the extreme situation of a population that would go extinct without supportive breeding, it would be better to maintain a genetically depauperate population than to let it die. It is at least possible that some current populations are small enough for the situation to be considered extreme. Using the general model and variable designation for supportive breeding that is outlined in Appendix C, an example is depicted in Figure 5-1. A declining initial population (N) of 50 is supported with progeny from five captive fish with a much higher average reproductive rate (adult to adult) than the wild fish. The support immediately results in a growing actual population. The Ne stops declining, in-

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Atlantic Salmon in Maine FIGURE 5-1 Census size (N), effective size (Ne), and cumulative harmonic mean of effective size () during 10 generations of supportive breeding in a population of 50 individuals that would be declining if left on its own (initial N = 50). In each generation a fixed number of Nc = 5 individuals are caught at random and brought into captivity for reproduction. The mean number of progeny per individual is μc = 10 in captivity and μw = 1.5 in the wild, with variances σ2w = 7.5, and σ2c = 50 (five times the corresponding initial μ-value). The dashed line indicates the effective size in the absence of supportive breeding.

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Atlantic Salmon in Maine creases at a much slower rate than actual population size, and levels out at an Ne that is considerably smaller than N but still much larger than it would have been without support. This example only depicts a particular set of parameter values, and the expected effect of a support program must be evaluated with respect to specific conditions and options. It appears, for example, that the program in Figure 5-1 could be made more “genetically successful” by reducing the variance of family size in captivity or by increasing the number of captive fish in later generations, when the total population size has increased. However, those scenarios have not been evaluated numerically by the committee. The above considerations lead to advice on how to reduce the adverse genetic effects of supportive breeding by holding the number of progeny to be stocked from each mating to a constant. If the mean and variance of reproductive rate are equal (the usual Poisson assumption), then (ignoring the overlapping generations), where is the mean number of progeny per individual, and V(k) is the variance (Wright 1938). Under Poisson assumptions, V(k) = , reducing the equation to, and in a growing ( >1) population, Ne is only slightly smaller than N. With much greater than Poisson variance in reproductive output (the usual case, V(k) >> ), the reduction of Ne is greater, that is, Ne << N. However, if V(k) is reduced to 0 by holding the number of progeny per mating to a constant size, , then Ne is increased to Thus, given that one-on-one matings are being used in the hatchery, maximum Ne is achieved by holding the number of progeny per mating to a constant. Loss of Genetic Variability among Populations (Population Identity) Crosses made among fish from multiple populations result in loss of genetic distinctness of each individual population (that is, population identity). One potentially adverse outcome of mixing distinct populations

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Atlantic Salmon in Maine is a reduction in fitness in the admixed population due to disruption of local adaptation or of co-adapted gene complexes (reviewed by Hallerman 2002, Kapuscinski and Brister 2001). Atlantic salmon in Maine, like many fish species, are part of a larger metapopulation, in which relatively isolated subpopulations are connected by low levels of gene flow via straying migrants (NRC 1996a, 2002a). Isolation allows subpopulations to adapt to local environmental conditions. There is almost no hard evidence on the degree to which remnant populations of Atlantic salmon in Maine rivers are locally adapted. The assumption, however, must be that those few fish that return to spawn are at least as well adapted to local conditions as those that fail to return. Sheehan (T. Sheehan, NMFS, personal communication, 2002) conducted a “common-garden” study of three river-specific populations, in which progeny of fish from different rivers are raised in similar environmental conditions. The progeny showed different growth trajectories, a result that is consistent with that expected from locally adapted populations. While Sheehan’s study is not definitive, because of design limitations, it is suggestive of the kind of local adaptation that is common in wild populations of salmonids and that forms the basis of the concern for maintaining the remnants of the natural metapopulation structure of wild salmon in Maine. Low amounts of migration can counter the inevitable loss of genetic variability in isolated populations without overwhelming local forces of adaptation. Massive hatchery mixing of distinct gene pools, however, is likely to overwhelm the local forces of natural selection, because the proportion of breeders coming from another gene pool is typically much larger and the level of genetic differences between the imported and local populations can be much greater (due to ease of transporting salmon from far distant locations). The Craig Brook stocking program avoids this genetic hazard through separate rearing and crossing of river-specific groups for each of the DPS and Penobscot rivers. Outbreeding between genetically distinct populations can sometimes improve fitness in the wild, but such outbreeding enhancement is most likely when hybridization alleviates pre-existing inbreeding depression within one or both pre-mixed populations (Waples 1995). Although Ferguson et al. (1988) found some evidence of superior fitness of first-generation hybrids between two non-inbred populations of cutthroat trout, superior fitness of hybrids often disappears in subsequent generations when the hybrids backcross to a parental population (Gharrett and Smoker 1991). To date, evidence of inbreeding depression is lacking in Atlantic salmon populations in Maine, despite their depressed status. Natural straying probably occurs often enough to provide gene flow without disrupting local adaptation (NRC 2002a).

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Atlantic Salmon in Maine which helps to limit the severity of insect and disease impacts in a monoculture. While not strictly an organic crop, blueberry growers are eager to promote the health benefits (high antioxidant content) and “wild mystique” of their product especially in the bakery trade and European and specialty markets (WBANA 2001). Therefore, most growers, especially large commercial operations, strive to minimize the use of agricultural chemicals. Blueberry growers have supported the University of Maine’s research and extension efforts since 1945. As a result, traditional practices and trial and error approaches have been supplanted by integrated pest management (IPM), integrated crop management (ICM), and other methods and approaches aimed at increasing efficiency and reducing cumulative environmental impact. Current research on water use efficiency holds promise for the improvement of irrigation practices, particularly the reduction or elimination of return flow. The establishment or enhancement of riparian buffers and windbreaks also shows an increasing awareness of potential off-site impacts. Prescribed fire is used to limit weed competition and prevent natural regeneration of trees and other forest vegetation in the blueberry fields. Although its effects should be quantified, it is likely that burning is more desirable than the use of herbicides especially in the Down East watersheds. Water quality data are so limited in the Down East region that it is not possible to quantify the effect, if any, of agricultural chemicals on Atlantic salmon and other parts of the aquatic ecosystem. A multiyear program of soil solution, groundwater, and stream chemistry, in an “above and below” or paired watershed (reference and treatment) design that includes flow proportional sampling is needed. Biomonitoring methods using aquatic macroinvertebrates also may help to assess mechanisms, patterns, and trends. Riparian Forest Buffers The riparian area is the transition between terrestrial and aquatic ecosystems (NRC 2002d). Vegetation in the riparian zone is critically important to the biotic integrity of aquatic ecosystems. Trees and other forest vegetation provide a suite of ecological services: Shade that helps to regulate water temperature Root support to stabilize banks and floodplains Inputs of organic carbon that comprise the base of the food web Leaf litter to protect soil from erosion and maintain high surface permeability Large woody debris to form pool habitat Hydraulic roughness to dissipate the energy of flood flows

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Atlantic Salmon in Maine Nutrient uptake and assimilation Travel corridors for terrestrial wildlife and amphibians To maintain these ecological services, the width of riparian forest buffers should be modified in relation to landform (both the floodplain and adjacent uplands) and the character and condition of the forest (Verry et al. 2000). While fixed-width buffer strips (usually 100 feet) are certainly preferable to gaps, one-size-fits-all does not fit most situations. Contemporary methods use the height of mature trees, slope, and landform to devise an appropriate and conservative (in both senses of the word) riparian forest buffer. The largest landowner in the Down East region, International Paper Company (formerly lands of Champion International), maintains a 1,000-foot buffer along the main stem of rivers that traverse its forestland. In an area where trees rarely exceed 100 feet, this represents corporate decision making in the face of ecological, regulatory, and political uncertainty. Notably, International Paper’s mapping and harvest planning also includes riparian forest buffers on headwater tributaries. This avoids the common approach of designating large buffers on large rivers while neglecting small headwater streams that constitute the majority of the system. As a result, NPS pollution that enters in upstream areas flows right past large downstream buffers. Project SHARE is undertaking a regionwide assessment of riparian forest buffers (RFBs). Using aerial photography, satellite imagery, geographic information systems (GIS), and field inspections, they will identify stream reaches that lack RFBs and devise site-specific restoration plans. They also have established a native plant nursery to produce growing stock (both trees and shrubs) that is appropriate for local conditions. The USDA Forest Service Northeastern Area is providing funding and technical assistance for this project. Forest Management Planning A brief summary is needed to explore the potential interaction of forestry and Atlantic salmon in Maine. Contemporary forest management involves the harvesting of trees to generate a sustainable supply of wood fiber for paper, lumber, and other forest products while avoiding or mitigating adverse impacts on other resources—water, fisheries, wildlife, recreation, aesthetics, and spiritual values. Long-term forest management on large public and industrial landholdings typically uses a 20-year strategic planning horizon (with detailed forest growth and yield projections that extend 100 to 200 years into the future) to systematically organize operations at the landscape scale. A 5-year business plan is used to optimize interrelated components and to determine sequencing of key components,

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Atlantic Salmon in Maine such as (1) harvest areas and silvicultural prescriptions, (2) road construction, reactivation, or reclamation, (3) harvest schedules and expected volumes, and (4) plans and practices to protect other forest resources. Annual operating plans contain detailed schedules, contracts, budgets, health and safety, and staffing requirements, and contingency plans for unseasonable weather, natural disturbances (e.g., wildfires, floods), and short-term fluctuations in mill production schedules. Five-year plans are updated annually to reflect changes in the forest, including natural disturbance events. The 20-year plan serves as the benchmark as the 5-year plan is implemented. Recent advances in computing and mapping technology have enhanced the detail and accuracy of forest management plans in several important ways. GIS have largely replaced conventional maps and aerial photographs that were the foundation of management planning from the 1930s through the late-1980s. GIS databases allow planners and managers to intersect, combine, or overlay themes or digital maps that represent multiple attributes of forest ecosystems. Digital imagery from satellites (10 to 30 meter resolution) or conventional aircraft (0.5 to 1 meter resolution) provides accurate depictions of forest vegetation types, wetlands, streams, rivers, and lakes. When coupled with field surveys using sample plots located with GPS and/or low-altitude flyovers with helicopters or light planes, the species composition, biomass, character, and condition of forest stands can be accurately mapped over large areas. This includes tree, shrub, and herbaceous cover in recently harvested areas. Sample plot and aerial survey data are extended over the remainder of the forest using the GIS and a wide range of statistical methods. Other ecosystem measurements are used to quantify the influence, positive or negative, of forest management and compliance with environmental laws and regulations. These efforts may include road stability surveys, stream reach assessments, water quality measurements, biomonitoring with aquatic macroinvertebrates, wildlife and recreational user surveys. How these data are used in planning and operations varies widely in the public and private sector. Whether environmental monitoring is proactive or reactive is largely a function of the corporate philosophy of the firm or agency. There are several ways that state-of-the-art forest management planning could help to conserve Atlantic salmon populations in Maine. The first is simply by using terrain (digital elevation model), soils, land-cover data, and the GIS to map areas with management restrictions. These include, but are not limited to, (1) the designation of conservative riparian buffers along streams, lakes, and rivers, (2) contract restrictions on equipment and operating conditions (e.g., frozen or dry season only, slopes less than 15%), or (3) acceptable silvicultural systems (e.g., small group selection, patch cuts, patch retention). The second is to distribute the spatial

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Atlantic Salmon in Maine pattern and temporal sequence of harvesting in a way that anticipates and avoids adverse cumulative effects on aquatic ecosystems. A recent review and synthesis of long-term paired watershed studies by Hornbeck and colleagues (1993, 1997) suggest that reductions of forest biomass or forest area of 20% to 30% are needed to generate significant changes in water yield (stream flow volume and timing). Without significant increase in soil moisture and stream flow, nutrients mobilized by decomposition of organic matter are used by the trees and other forest vegetation adjacent to the openings or patches left by harvested trees. Even if the volume or area harvested exceeds 20% to 30% of any given watershed, the hydrologic influence of timber harvesting is short-lived in temperate climates. As the total leaf area of the regenerating stand approaches the mature trees that were cut, water yield returns to pre-harvest levels, usually in 3 to 5 years. The 1997 conservation plan notes that harvest areas for the period 1990 to 1994 ranged from 2% to 10% of the Down East watersheds. Depending on the spatial distribution, regeneration success, and growth rates, this may be far below the threshold identified by Hornbeck and colleagues (1993, 1997) or exceed thresholds at the subwatershed scale. In the latter case, the influence of timber harvesting near smaller tributaries with unobstructed, high-quality salmon habitat could be substantial even though they are protected with riparian forest buffers. After delineating watersheds across a range of spatial scales—from first-order streams, to second- and third-order tributaries, up to the entire watershed for each river—analysts could use the GIS to test the spatial arrangement and temporal sequence of harvesting operations in proposed annual, 5-year, and 20-year plans. Using a spatially distributed model such as SNAP (Scheduling and Network Analysis Program, Sessions and Sessions 1997), a decision rule of, for example, 30% forest biomass removal would restrict subsequent harvests for a 5-year period in that headwater area. By summing all the harvested areas at intermediate and landscape scales, the same space and time thresholds could be evaluated. Of course, this requires landholdings of sufficient size to balance constraints on harvested area and time between entries, losses of fiber to natural disturbance, forest growth and yield, and the volume and grade requirements of the mills. It also adds additional complexity to road network design, use, and maintenance. In other words, since roads are clearly a more significant cause of adverse impacts than harvesting, a spatial and temporal harvesting pattern that requires a greater net road mileage would be counterproductive. In fact, minimizing the length of the active road network and the number of road-stream crossings could be used as additional objective functions in the model. Iterative or Monte Carlo simulation methods can be used to enumerate a broad range of possible management scenarios.

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Atlantic Salmon in Maine Forestry Best Management Practices The profession of forestry was established in North America in response to the waste and destruction caused with industrial logging, floods, and catastrophic fires in late-1800s. While many associate best management practices (BMPs; more appropriately named conservation-management practices [CMPs] in Canada) with the Clean Water Act and other 1970s-vintage environmental laws and regulations, they have always been a central part of a professional forester’s work. The work of Civilian Conservation Corps (CCC) in the 1930s could be largely characterized as the landscape- or even national-scale application of BMPs. For example, the reforestation of eroding farm fields, pastures, cutover and burned areas; stabilization and improvement of roads; construction of bridges over perennial streams (to replace fords and undersized box culverts); and a wide range of other activities transformed millions of acres in a decade of unprecedented effort and commitment. Unfortunately, World War II, the post-war building boom in the 1950s and 1960s, rapid mechanization of logging and road construction, coupled with the erosion of management standards and a strong conservation ethic, led to a general relapse to 1890s standards of practice. Progressive companies and diligent government agencies now require a suite of BMPs to protect the functions and values of forest ecosystems. A comprehensive system of BMPs is needed to reinforce the effectiveness of individual practices and ensure that overall efforts are cost-effective and durable. Key principles for the adaptation or development of BMPs for regional and site-specific conditions include the following: BMPs should be integrated with routine planning and operations; they should not be an after-the-fact addition or reaction to undesirable conditions. Leaf litter and soil surface should be protected because it helps to retain the favorable hydraulic properties of forest soils (e.g., permeability and infiltration rate) and to avoid overland flow, soil erosion, nutrient mobilization, and sediment transport. Whenever overland flow occurs, it should be deliberately dissipated or dispersed before it increases in volume and momentum. Hydrologic connections between roads and harvest units and streams, lakes, and wetlands should be avoided. Timber harvesting, road construction, road reclamation, and post-harvest site stabilization efforts should be adjusted to terrain and weather conditions. Biological and physical control measures should be combined to enhance their effectiveness.

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Atlantic Salmon in Maine Forestry BMPs have been developed, tested, and refined for decades and number in the hundreds. Some examples of BMPs derived from the principles enumerated above, in addition to those already discussed for roads and riparian areas, include the following: Contract specifications, terms, and conditions that clearly state acceptable start and end dates, provisions for delays and extensions based on field conditions, performance standards for all aspects of the operation, performance bonds held in escrow accounts to motivate such factors as compliance and equipment type, size, and weight limits. Temporary bridges or brush mats to cross ephemeral streams or wetlands. Seeding of exposed soil with annual winter rye to ensure rapid revegetation while limiting the permanent introduction of exotic grasses and herbaceous plants (the rye dies and adds organic matter to soil as native species recolonize the site). Limiting the size of log landings by matching the log haul to harvest production rates (maximizing throughput to minimize the size of the disturbed area). Strict hazardous materials handling procedures in relation to heavy equipment maintenance and refueling operations. Gates on temporary logging roads to limit access by all-terrain and four-wheel-drive vehicles…and associated damage. Supervision by professional foresters on an as-needed basis (e.g., daily, weekly, random unannounced visits) to ensure compliance with contract specifications. Recreational Use Many forms of outdoor recreation (snowshoeing, cross-skiing, snowmobiling, canoeing, kayaking, hiking on well-designed trails, hunting, etc.) generate little or no impact on soils, water, and aquatic ecosystems. All-terrain and off-road vehicles (ATVs and ORVs) are a recent and notable exception. ATVs (“quads” or “four-wheelers”) and ORVs (four-wheel-drive trucks and sport-utility vehicles) can cause substantial damage to soils, water, and aquatic ecosystems unless their use is carefully planned and managed. Whenever people reenact television commercials by fording streams, climbing steep banks or hills, and mixing, rutting, and compacting soil, they cause a host of environmental impacts. This damage may be inadvertent or intentional, but in either case, their actions can negate months or years of work to control NPS pollution in one Saturday afternoon.

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Atlantic Salmon in Maine COSTS OF OPTIONS Estimating the costs of the options the committee has recommended for improving the survival prospects of Atlantic salmon in Maine is complex. The least difficult aspect of them—and the only one the committee addresses below—is the direct monetary costs of executing the options. Even those costs are accompanied by uncertainty, but a rough idea of their order of magnitude is provided below for some of the options, along with a discussion of the uncertainties associated with the estimates. The committee cannot provide any estimates of indirect costs and benefits, but they are important when considering the costs of various actions, and so they are discussed briefly here. Many costs and benefits are not directly associated monetarily with a particular option. For example, time often is spent in lobbying for various outcomes, negotiating, legal activity, reviewing permit applications, consulting with colleagues and experts, and so on. These are real costs but only rarely are they directly accounted for. Other costs accrue over time, for example, as an accumulation of adverse effects of pollution or dams, adverse financial effects on businesses that are required to contribute to costs of executing options, or the accumulated effects on planning of uncertainty over what measures will be taken and when. Different groups, organizations, and individuals have various interests. They can be affected differently by factors related to these options, some benefiting more than others from the status quo, others benefiting more than others from the proposed options. Most of the human activities that affect the survival of Atlantic salmon in Maine generate benefits to at least some people. To the extent that those activities are constrained for any reason, including protecting salmon, some costs will occur in the form of foregone benefits. In a few cases, such as a dam in disrepair that generates no power and provides no flood protection or recreational benefits, an action to protect salmon will probably have only direct costs and benefits, but such cases will be in the minority. Similarly, liming a small acidified stream probably has few hidden costs. But for the others, the hidden or indirect costs and benefits can be substantial. For example, if a dam that blocks fish passage is retained, the dam’s owners benefit from any net revenues generated by the dam and property owners adjacent to the pool behind the dam benefit from owning waterfront property. On the other hand, other groups and individuals suffer from the absence of migratory fish above the dam and from the loss of a free-flowing river there. Different groups bear costs and enjoy benefits differently. For example, if a dam is removed, any loss of revenue associated with that removal directly affects the dam’s owners, and any loss of tax revenue

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Atlantic Salmon in Maine affects the relevant taxing jurisdiction. Property owners adjacent to the pool behind the dam lose the benefit of owning waterfront property. Other groups, however, benefit from the presence of migratory fish in new stretches of the river and from the existence of a free-flowing river. If an option affects the profitability of a salmon farm, its owners bear the loss. In addition, there are broader societal effects of options. In the case of the salmon farm, jobs could be lost if it loses profitability, and shareholders could be affected economically. In addition, jobs likely would be lost by those who provide products such as feed to the industry, and its demise could also affect retail and real-estate sales. But salmon anglers, commercial fishers, and the tourist industry could perhaps benefit from increased populations of wild salmon. An additional complication is the uncertainty surrounding the effect of an option on salmon and its effect on other species of interest. There is no guarantee that implementing any of the options the committee recommends, or even all of them together, will lead to a recovery of wild salmon populations in Maine. That uncertainty is at least partially offset by the high probability that other species as well as a variety of ecosystem goods and services, such as provision of clean air and water, will benefit from the options. Other complications include the difficulty of taking into account the costs and benefits that might accrue to future generations; the costs and benefits of secondary effects, such as coming into compliance with environmental laws and regulations or the consequences of altering commercial operations; and other societal consequences. Many of the above issues are discussed in greater detail in Heinz Center (2002), especially with respect to dam removal. The above and other factors should be considered for a full evaluation of the costs and benefits of the options and decisions about what actions to take. Even though the committee cannot provide quantitative estimates of those factors, they are important when considering the costs of various actions, and they should be taken into account. Dam Removal The cost of removing a dam depends on many factors, including the dam’s size; how it was constructed; the need for compensation to its owners or users or beneficiaries; the amount of administrative, political, and legal work that is done. The societal costs and benefits of removing dams are also difficult to quantify (American Rivers et al. 1999, Heinz Center 2002). Below we provide some examples.

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Atlantic Salmon in Maine Edwards Dam This privately owned dam, 917 feet long and 24 feet high, on the Kennebec River was removed in 1999. The Federal Energy Regulatory Commission (FERC) denied the request for relicensing. Following an appeal, a settlement was reached whereby the owners avoided building a $9 million fish ladder that would have been required by agreeing to the dam’s removal. They paid the city of Augusta, a co-licensee, $100,000 to make up for lost revenue. Bath Iron Works, a shipbuilder, agreed to contribute $2.5 million in exchange for favorable consideration of its request to expand its shipyard on the river, and the Kennebec Hydro Developers Group of upstream dam operators contributed $4.75 million in return for extra time allowed for the installation of fish passage devices at their dams (Associated Press 1998). The money was used to remove the dam and to restore fish habitat. American Rivers et al. (1999) reported that it cost $2.9 million to remove the dam, including $800,000 for engineering and permitting, and that $4.85 million was provided for associated fish restoration efforts in the basin. The costs listed above total more than $7 million. However, that is not the total cost of removing the dam. The Kennebec Hydro Developers Group has saved money by being allowed to postpone the installation of fish-passage devices, and the Bath Iron Works had the opportunity to increase revenue by expanding its shipyard. The time spent by all the people involved in reviewing license applications, filing appeals, lobbying, and other related activities is not included in the total. Societal benefits and costs are not included. The Edwards Dam was one of the larger Maine dams obstructing the passage of salmon and adversely affecting their habitat. It took approximately 6 years to remove the dam: the license expired in 1993, the relicensing application was first denied in 1997, the agreement was signed in 1998, and the dam came down in 1999. Smaller dams, especially those that do not generate any power, would cost less and probably take less time to remove than Edwards, although there often are objections to the removal of dams that have large pools behind them. The objections often focus on loss of recreational opportunities and loss of water-front by property owners. Grist Mill Dam The Grist Mill Dam (GMD) on Souadabscook Stream is at the head-of-tide on this tributary to the Penobscot River and is the first obstacle anadromous fish encounter on returning to freshwater in this drainage. The dam was 14 feet high, 75 feet wide, and its removal in October 1998

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Atlantic Salmon in Maine cost $56,000 (American Rivers et al. 1999). Additional upstream dams were breached as well. Four salmon-spawning sites were discovered upstream of GMD in December 1998 (American Rivers et al. 1999). The process that led to the dam’s removal took approximately 3 years. Other Dams Estimated costs of dam removal have exceeded $100 million for the Glines Canyon and Elwha dams on the Elwha River in northwest Washington (NRC 1996a). The NRC report (1996a) indicated that the large main-stem Columbia and Snake river dams would be much more expensive to remove; perhaps that cost could exceed $1 billion for each of those larger dams. The costs can be as low as thousands of dollars for removing small brush or even earth dams (e.g., $1,500 for the removal of the 3-foot-high Amish dam on Muddy Creek, PA, reported by American Rivers et al. [1999]). Several dams removed in Wisconsin, at least one of which was 13 feet high, cost a few hundred thousand dollars each, including restoring adjacent lands (American Rivers et al. 1999, Wisconsin River Alliance 2001). The recent agreement to remove two Penobscot River dams has an agreed-on initial cost of $25 million to be raised over 5 years (Richardson 2003). Estimated Cost of Removing Maine Dams Dams blocking Maine’s rivers and streams range widely in size and construction materials. Most are smaller than the Edwards Dam. Assuming a cost of from $100,000 to $3 million per dam and the removal of three to five dams per year, the cost of this option would be between $300,000 and $15 million per year. The bearers of the cost would have to be determined by negotiation, legal action, or other processes. More information on estimating costs of dam removal is provided by the Heinz Center (2002). Liming (Deacidifying) Streams Liming is a method of reducing the acidity of streams by adding limestone, primarily calcium carbonate (CaCO3). It often is regarded as one of the lower-cost methods of rehabilitating acid streams (Helfrich et al. 2000, Weigmann et al. 1993). However, costs vary according to the size of the stream and the equipment used. The cost of the limestone is the smallest expense, about $25–$100 per ton in 1993, including transportation. A rotary-drum limestone dispenser capable of dispensing 500 tons of limestone per year would have cost about $132,000 plus $16,500 for

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Atlantic Salmon in Maine maintenance and perhaps $25,000 per year for the limestone, or an annual cost of a little more than $40,000. For 2,200 tons of limestone per year, the estimated costs in 1993 were $55,000 for an electric doser plus $12,100 per year to maintain and $110,000 for the limestone for an annual cost of $122,100. It would thus appear that this option, which would probably not incur significant ancillary political and societal costs, would be on the order of $100,000 initial cost plus $50,000–$100,000 per year for each stream treated. Hatcheries The committee’s recommendations for improving hatchery operations would not require major additional expenditures in addition to what is currently being spent on federal hatchery operations for Atlantic salmon in Maine. However, there would be some additional costs. Tagging fry would cost some money and determining whether they are tagged and reading the tags would cost as well. A properly conducted research program involving paired streams might require additional employees and support and equipment. Salmon Farms The cost of many of the committee’s suggested modifications of salmon farming cannot be reliably estimated because the costs of salmon farming operations are proprietary and because many factors—for example, the willingness of employees to move to work at a new site, the costs of various permitting and other legal and political requirements—are unknown. Nonetheless, it is clear that most of the modifications would likely cost enough to eliminate the profitability of salmon farms. Tagging all the fish reared on farms could be done most economically with an otolith tag, such as Terramycin, but even so, it would add significant additional expense to the operations. In addition, it would not provide a way to determine the source of any captured escapees. Coded-wire tags would allow identification of the origin of a particular fish but would be more expensive than otolith tags. This means that requiring most of the suggested modifications to salmon farms would result in the elimination of the salmon-farming industry in Maine, with the attendant costs of unemployment and other societal costs or it would require public or private subsidies.