Summary

Atlantic salmon in Maine, once abundant, are now seriously depleted. Hundreds of thousands of adults returned to Maine’s rivers and streams each year in historical times. In 2002, it is estimated that only 871 salmon returned to spawn in all Maine rivers. Atlantic salmon were listed as endangered under the federal Endangered Species Act (ESA) in November 2000. The listing covers the wild fish in eight Maine rivers (Figure S-1) as a single “distinct population segment” (DPS). Only 33 fish returned to those eight rivers, often called the DPS rivers, in 2002. (These estimates of returning salmon are minimal estimates, and the actual numbers are probably greater; nonetheless, the decline in salmon numbers is real and very serious.)

The controversy in Maine that accompanied the ESA listing led Congress to request the National Research Council’s (NRC’s) advice on the science relevant to understanding and reversing the declines in Maine salmon populations. The charge to the NRC’s Committee on Atlantic Salmon in Maine (Box S-1) included an interim report that focused on the genetic makeup of Maine Atlantic salmon populations; that report was published in January 2002. The charge for the final report included a broader look at factors that have caused Maine’s salmon populations to decline and the options for helping them to recover. This is the final report.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 1
Atlantic Salmon in Maine Summary Atlantic salmon in Maine, once abundant, are now seriously depleted. Hundreds of thousands of adults returned to Maine’s rivers and streams each year in historical times. In 2002, it is estimated that only 871 salmon returned to spawn in all Maine rivers. Atlantic salmon were listed as endangered under the federal Endangered Species Act (ESA) in November 2000. The listing covers the wild fish in eight Maine rivers (Figure S-1) as a single “distinct population segment” (DPS). Only 33 fish returned to those eight rivers, often called the DPS rivers, in 2002. (These estimates of returning salmon are minimal estimates, and the actual numbers are probably greater; nonetheless, the decline in salmon numbers is real and very serious.) The controversy in Maine that accompanied the ESA listing led Congress to request the National Research Council’s (NRC’s) advice on the science relevant to understanding and reversing the declines in Maine salmon populations. The charge to the NRC’s Committee on Atlantic Salmon in Maine (Box S-1) included an interim report that focused on the genetic makeup of Maine Atlantic salmon populations; that report was published in January 2002. The charge for the final report included a broader look at factors that have caused Maine’s salmon populations to decline and the options for helping them to recover. This is the final report.

OCR for page 1
Atlantic Salmon in Maine FIGURE S-1 USA Atlantic salmon rivers with active restoration and recovery programs in New England. The eight DPS rivers in Maine with Atlantic salmon listed as endangered under the ESA are (5) Dennys, (6) East Machias, (7) Machias, (8) Pleasant, (9) Narraguagus, (12a) Cove Brook, (13) Ducktrap, and (14) Sheepscot. SOURCE: Baum et al. 2002. Reprinted with permission of the author.

OCR for page 1
Atlantic Salmon in Maine BOX S-1 Committee Statement of Task A multidisciplinary committee will review the available scientific information on the status of Atlantic salmon populations in Maine and, where relevant, in adjacent areas. The committee will assess causes of the declines of their populations and the current threats to the continued survival of salmon, will evaluate the evidence on the population structure of those salmon, and will evaluate options for improving the survival of salmon. In assessing information, the committee will identify significant knowledge gaps and suggest additional research that would be important to the conservation and recovery of salmon populations. Factors to be evaluated include the nature and distinctness of salmon populations in Maine rivers and surrounding areas; the interactions between aquaculture, hatchery, and wild populations; terrestrial and marine environmental factors affecting salmon populations; the effects on salmon of changes in the hydrology of Maine streams; and the effects on salmon of subsistence, recreational, and commercial fishing in freshwater and ocean areas in and around Maine. A brief interim report will be produced within 9 months after formation of the committee. The interim report will address the genetic makeup of wild salmon populations in Maine and its possible relationship to recovery activities. A final report at the end of the study will describe and synthesize the information available on the biology of Atlantic salmon, the causes of their population declines, and the threats to their continued survival. It will evaluate and describe options for enhancing their continued survival and recovery and will provide some approximate estimates of the relative costs of the various options. SALMON BIOLOGY Naturally reproducing populations of Atlantic salmon occur in rivers and streams from southwestern Maine to northwestern Europe. Historically, they were found in the Hudson River in New York and north and east to the Canadian border, but today they are found only in Maine, from the Sheepscot River to the Canadian border. The populations have declined drastically, from perhaps half a million adults returning to all U.S. rivers each year in the early 1800s to a minimum estimate of 1,050 in 2001. Most U.S. Atlantic salmon are in Maine rivers, and 780 (90%) of those returned to only one river, the Penobscot, in 2002. Salmon spawn in freshwater, where the young hatch and grow for 1–3 years before migrating to sea. At sea, they grow faster in the rich marine environment and then return as adults to the rivers where they hatched (called natal streams) to spawn—a life history called anadromy. Most adult salmon die after spawning, but some return to the ocean, and some of those fish return to spawn again. Some males mature early and survive spawning more often than adults do.

OCR for page 1
Atlantic Salmon in Maine The homing of salmon provides an opportunity for the salmon to adapt to environmental conditions in their natal streams. The occasional straying of returning adults to streams other than their natal streams is probably important evolutionarily, because it allows recolonization of a stream if the local population dies out and provides for small infusions of new genetic material for continued evolutionary adaptation to changing conditions. The complex life-history pattern of anadromy exposes salmon both in the ocean and in streams to predation, fishing, habitat degradation, and other environmental perturbations. Understanding the causes of population decline is thus also complicated. In addition to anadromous Atlantic salmon, Maine has populations of Atlantic salmon that complete their entire life history in freshwater. They are called landlocked salmon or ouananiche. They are the same species as the anadromous form, although there is some genetic difference between them. They are not endangered, but because they strongly resemble anadromous salmon and sometimes compete with them, they can complicate efforts to rehabilitate wild anadromous populations. HATCHERIES AND AQUACULTURE Augmentation of wild populations of Maine salmon with hatchery releases began in the early 1870s. At first, young fish were obtained from Lake Ontario. Later, the Craig Brook Hatchery in East Orland, Maine, using eggs from Penobscot River fish, was the stocking source. By the 1920s, Canadian eggs were being used, followed in the 1940s by eggs from the Machias, Penobscot, and Dennys rivers of Maine. In the 1950s and 1960s, some eggs of Canadian origin again were used, but by the late 1960s, eggs from Maine’s Machias, Narraguagus, and Penobscot rivers were used. Fish reared in hatcheries derived from Penobscot River fish were used until late 1991, when the practice of river-specific stocking was adopted. The protocol used since involves catching young, actively feeding fish (parr) in the river, rearing them to maturity in the hatchery, mating them, and releasing the resulting fry into their native rivers before they start to feed. Stocking, at least until 1992, added to rivers many fish (and eggs) whose genotypes did not reflect adaptation to the local environment. In addition, aquaculture (farming) of Atlantic salmon began in Maine in the 1980s, the first fish for market being produced in 1987. Derived in part from European Atlantic salmon, the genetic strains used for fish farming are even more different from native strains than are hatchery strains. Farm fish escape at all life stages, despite the efforts of producers to prevent escapes. In some years and in some rivers, more escaped farm fish return to spawn than wild fish. The impact of escapees on the genet-

OCR for page 1
Atlantic Salmon in Maine ics of wild populations is not well documented in Maine. Both hatchery-and pen-reared fish compete poorly with wild fish in other rivers that have been studied, but because there are so many escaped farm fish compared with wild fish in some rivers, some impact is likely to have occurred. The addition of so many nonwild genotypes from hatcheries and from aquaculture escapees has led some to conclude that the fish returning to spawn in Maine’s rivers could not possibly represent anything more than a mix of genotypes from Europe, Canada, and Maine. If that were true, then options for conservation might be considerably different from those that might be undertaken if the wild fish in Maine were genetically distinct, and that is why it is important to understand the genetic makeup of the wild salmon populations in Maine and the effects that hatcheries might have on it. THE GENETICS OF MAINE SALMON In its January 2002 interim report, the committee assessed how Maine salmon populations differ from other Atlantic salmon populations and among themselves. The committee addressed the question at three levels. First, are North American Atlantic salmon genetically different from European salmon? Second, are Maine salmon distinct from Canadian salmon? Third, to what degree are salmon populations in the eight Maine rivers in the ESA listing distinct from each other? The committee concluded that North American Atlantic salmon are clearly distinct genetically from European salmon. In addition, despite the extensive additions of nonnative hatchery and aquaculture genotypes to Maine’s rivers, the evidence is surprisingly strong that the wild salmon in Maine are genetically distinct from Canadian salmon. Furthermore, there is considerable genetic divergence among populations in the eight Maine rivers where wild salmon are found. The committee concluded that wild salmon in Maine do not reflect only (or even mainly) the result of decades of hatchery stocking. It is not possible to say whether or to what degree the genetic differences reflect adaptation to local conditions as opposed to random processes associated with small population sizes or some influence of stocking. However, the pattern of genetic variation seen among Maine streams is similar to patterns seen elsewhere in salmon and their relatives where no stocking has occurred. HUMAN ALTERATION OF THE ENVIRONMENT Maine’s environment has been substantially altered by human use. Before humans arrived, the advance and retreat of continental ice sheets

OCR for page 1
Atlantic Salmon in Maine during the Pleistocene epoch (10,000 to about 1.5 million years ago) had a dominant influence on landforms and resulting stream networks and soils of Maine. Glaciers shaped mountains and valleys; left sand and gravel deposits; and carved out hundreds of lakes, ponds, and depressions that are now wetlands. The dominant soil types are a direct result of glaciation, a cold, wet climate, and forest succession over the past 10,000 years. In general, the soils are well drained, acidic, and relatively unfertile. The properties of the soils and watersheds generally yield high-quality streams and rivers. Anthropogenic disturbance has occurred for centuries in New England’s forests. Before European settlement, Native Americans used fire to alter wildlife habitat and enhance or maintain the productivity of wild foods and medicinal plants. Since the mid-1700s, Maine’s environment has been altered by timber harvesting, clearing for agriculture, gradual abandonment of farmlands, industrial development, and more recently, residential land use. Maine was more than 92% forest in 1600. The forested area decreased dramatically as the combined effects of forest clearing for agriculture, industrial logging and milling, and subsequent forest fires reduced coverage to 53.2% by 1872. Forests have since regenerated on abandoned agricultural land and “cutover” areas, reversing the trend of deforestation of earlier centuries. In 1995, the Forest Service of the U.S. Department of Agriculture estimated that Maine’s forest cover was 89.6%, but the composition of the vegetation was much different than it had been a few centuries ago. By 1920, most of the forest left in the Penobscot, Kennebec, and Androscoggin watersheds had been altered by one or more logging cycles. By contrast, the Down East region (the part of Maine near and along the coast from roughly Penobscot Bay east to the border with Canada) still had areas of virgin forest exceeding 25,000 acres (10,125 hectares). A suite of socioeconomic and ecological factors might have contributed to the continued survival of wild Atlantic salmon in such rivers as the Narraguagus, Pleasant, Machias, East Machias, and Dennys. They include lower human population densities, less industrial use of the rivers, and a cooler climate. One trend that has not been significantly reversed is the presence of dams placed on Maine’s rivers for mills and other purposes. Most rivers there have one or more dams that reduce or eliminate fish passage and that alter riverine habitats. Some of the dams seem to have outlived their economic usefulness. To a significant degree, salmon recovery will depend on changing human activities that are threatening the survival of salmon. Understanding the factors that affect human activities is a prerequisite for designing effective policies that will alleviate the threats that the activities pose to

OCR for page 1
Atlantic Salmon in Maine the survival of salmon. In addition, many governance organizations are involved with salmon management. They include agencies of the federal and state government as well as local and nongovernmental organizations. The large number of such organizations complicates understanding of how their actions affect salmon. It also means that their ability to work together depends on thoughtful and careful communication and agreements. THREATS TO ATLANTIC SALMON IN MAINE Human activities that directly or indirectly threaten salmon include dams and hydropower projects, Atlantic salmon aquaculture, water extraction for agriculture, fishing, hatcheries, logging, road construction, development of land sites, acidification of their streams, and research. Predation—always part of the environment of salmon—has been influenced by declines in the number of salmon and by changes in the numbers and kinds of their predators. Those factors interact with many other factors on land, in freshwater, and at sea. The difficulty is not only to identify factors that threaten salmon but also to decide which ones are most critical and which ones can be mitigated or reversed. To address the difficulty of ranking the threats, the committee used a form of risk analysis. After threats have been identified and their severity and urgency ranked, decisions need to be made to address them. In some cases, legal or biological considerations might make the decisions obvious, but in most cases, decisions must be weighed against their likely effectiveness, cost, societal and political implications, and other consequences. The decision-making process should include people with local knowledge and people who must live with the consequences. In this report, the committee has provided two decision analyses it conducted as examples: placement of dams and managing risks of salmon farms. These examples of decision analyses are not intended as conclusions, because people with local knowledge and people who must live with the consequences of the decisions did not take part in the analyses. The committee’s conclusions focus on biological issues and on methods of gaining knowledge and understanding. The committee’s approach has been statewide, without a specific or exclusive focus on the eight DPS rivers or on the specific requirements of the ESA. That statewide approach was the committee’s charge, and it has a sound scientific basis: much additional salmon habitat in other watersheds should be used in rebuilding salmon populations. By far the greatest natural environmental asset for salmon in Maine is the Penobscot River. It is the largest river wholly in Maine, and it has more than 90% of all the adult Atlantic salmon returns in Maine. For years, the Penobscot

OCR for page 1
Atlantic Salmon in Maine was the major source of brood stock for salmon hatcheries. The Kennebec, Androscoggin, Saco, St. Croix, St. John, and other non-DPS rivers also are environmental assets for salmon. Biologically, a restoration program for Maine salmon would not make sense if it did not take advantage of those rivers as well as the DPS rivers. Dams Dams obstruct adult and juvenile salmon passage and alter riverine habitats, including water quality. As a result, they degrade or eliminate spawning and rearing habitat for Atlantic salmon in Maine. Although dams are not as important a problem on the DPS as on other Maine rivers, they have made an enormous amount of habitat unavailable to Maine salmon and have affected much of the habitat that is still available. Fish-passage facilities help migrations to some degree, but they have no effect on the riverine habitat affected by dams, and they are inadequate or completely absent on many dams. Hatcheries Hatcheries have been used in Maine to attempt to increase the populations of salmon since the 1870s. At first, no attention was paid to genetics. Fish used for brood stock came from various Canadian and Maine rivers. Canadian fish or eggs were not used in Maine after 1967 except in 1985 and 1986, but many nonnative fish were introduced in the earlier decades. In 1992, river-specific stocking was instituted for the eight DPS rivers. Even with river-specific stocking and the best available breeding protocols, hatcheries change the genetic makeup of salmon populations. Despite the efforts and money spent on rearing fish in hatcheries and stocking Maine’s rivers, salmon populations are now at the lowest levels ever recorded. The available information is not sufficient to conclude whether hatcheries in Maine can actually help to rehabilitate salmon populations, whether they might even be harming them, or whether other factors are affecting salmon so strongly that they overwhelm any good that hatcheries might do. Aquaculture Salmon farms rear salmon from eggs in hatcheries and then grow them to market size in net-pens near the coast. The salmon farms were established in Maine in the 1980s. Risks to wild populations from salmon

OCR for page 1
Atlantic Salmon in Maine farms include the transmission of disease, the concentration of parasites (sea lice) and predators around the net-pens to the detriment of wild salmon migrating nearby, and the escape of fish that can migrate up rivers and compete for space and mates with wild salmon. Disease has caused net-pens in Cobscook Bay to be dismantled and sterilized. Only limited research on and monitoring of the effects of salmon farms on Maine salmon have been carried out. Adverse effects of farms on wild fish have not been documented in Maine, but they have been elsewhere. There is no reason to believe that the harm to wild fish that has been documented elsewhere could not occur in Maine. Acid Deposition Deposition of sulfates and other chemicals from the atmosphere has acidified many lakes and streams in northeastern North America. In nearby Nova Scotia, acidification has led to the extirpation of salmon from more than a dozen rivers. Acid deposition has decreased in the past 25 years, but not all rivers and streams in Maine have become less acidified. The altered water chemistry of acidified streams especially affects the younger life stages of salmon and can be accompanied by a high mortality of smolts making the transition from freshwater to seawater. Although acidification has not been conclusively identified as a source of death for Atlantic salmon in Maine, recent information on poor survival of smolts and on water chemistry in Maine makes it appear that acidification could be a serious problem. Fishing Fishing has affected Maine salmon until very recently. At first, fishing was for subsistence, and its intensity is not well quantified. Commercial and recreational fishing were well established in the nineteenth century. Recreationally caught salmon were almost all killed before about 1985; but since 1994, most salmon caught have been released. High-seas fishing for salmon differs from fishing in rivers in that specific stocks cannot be targeted, so the number of Maine salmon caught by commercial ocean fishing is not easy to quantify. By 2000, all recreational angling for anadromous Atlantic salmon, even catch-and-release, was prohibited in Maine. Directed commercial fishing was eliminated by 1948 in Maine and almost completely eliminated at sea in 2002. Some poaching, accidental catch (bycatch), and take because of mistaken identity (anadromous Atlantic salmon resemble landlocked Atlantic salmon and brown trout) occur, but their magnitude is not known.

OCR for page 1
Atlantic Salmon in Maine Change in Atmospheric and Ocean Climate Atmospheric climate and oceanic conditions on earth have been changing for at least as long as life has existed; they will continue to change. Maine’s climate has warmed over the past three decades, and ocean conditions have changed as well. Continued warming would make it more difficult to rehabilitate wild salmon populations in Maine. Change in precipitation patterns and related phenomena, such as ice cover and timing of snowmelt, probably also would make things more difficult. Predation and Food Supply Predation has always been a feature of the lives of salmon, but human activities have probably increased its severity. Salmon predators include birds, mammals, other fish, and—at some life stages—invertebrates. Many rivers now contain nonnative species of fish, some of which are strongly piscivorous. Ocean fishing has changed the composition and food supply of potential salmon predators. In addition, protection afforded to marine mammals under the Marine Mammal Protection Act has resulted in increases in species that prey on salmon. Finally, the human depletion of salmon populations might have made them more vulnerable to other predators. These changes have probably also affected the kinds and amount of food available to salmon at various life stages. Research and Monitoring Research and monitoring are essential for understanding the dynamics, status, and trends of Atlantic salmon in Maine and for assessing the effects and effectiveness of management actions. However, the trauma associated with capturing, handling, anesthetizing, and sampling fluids and tissues from fish—especially young fish—can result in some deaths. When populations are very small, as they now are in most Maine rivers, it is essential to weigh the value of new information against the possibility of the harm to wild fish caused by handling. Governance Governance institutions have a strong influence on the success or failure of management of natural resources in general, as they do for anadromous Atlantic salmon in Maine. Although a considerable amount is known about relationships between governance structure and resource management, each case is unique, and much basic information is needed before governance structures can be fully adapted to improve resource

OCR for page 1
Atlantic Salmon in Maine management. In Maine (as in most other places), much of the required information has not been collected or analyzed. In addition, most governance structures have much broader mandates than only resource management, and that can make resource management more difficult. It would be helpful to increase coordination of efforts across local, state, federal, and international levels of organization; adapt governance structures to more closely match the biology and geography of salmon populations; include stakeholders in the risk-assessment and risk-management processes; and develop and improve of adaptive-management approaches that allow people to test the efficacy of various governance structures. RANKING THE THREATS The committee’s risk assessment led it to conclude that the greatest impediment to the increase of salmon populations in Maine is the obstruction of their passage up and down streams and degradation of their habitat caused by dams. This finding applies more to the non-DPS than to the DPS rivers, because the potential salmon habitat in the non-DPS rivers is so great. The mortality of salmon—especially smolts and post-smolts—in estuaries and at sea appears to be a very serious problem. Despite some uncertainty about the causes of the excess mortality, the committee concludes that acidification of streams has the potential to be a major impediment to the increase of salmon populations in Maine by contributing to that mortality. At the next level of importance, salmon farming has the potential to adversely affect salmon populations in Maine genetically and ecologically and might already have done so. Over the long term, hatchery supplementation of salmon populations in Maine is also likely to have deleterious genetic and possibly ecological effects. Predation and changes in oceanic conditions could be serious problems for salmon. Because populations of wild salmon in Maine are so low, the mortality associated with research and monitoring could be problematic. Current agricultural practices, including forestry, do not appear to be an important problem for Atlantic salmon in Maine, although their effects should be monitored, especially for erosion, reduction of vegetation cover, and water withdrawals. Fishing is currently prohibited; therefore, it is not an important problem for Maine salmon. A rich and complex network of governance institutions in Maine influences how humans affect salmon. As is often the case with complex environmental problems, more information is needed on how well governance institutions are working together, and whether the government authority is sufficient to develop and implement effective recovery programs.

OCR for page 1
Atlantic Salmon in Maine RECOMMENDATIONS Many recommendations have been made for the rehabilitation of Atlantic salmon populations in Maine. Most of them are sound, but there are too many recommended actions to take at once. Moreover, not all of them are equally urgent. Most of the actions discussed below also have been recommended by others, such as the Maine Atlantic Salmon Task Force, but here an attempt is made to set priorities for them and to recommend those actions most likely to be effective. Urgently Needed Actions There is an urgent need to reverse the decline of salmon populations in Maine if they are to be saved. Other than the Penobscot River, only 80 adult salmon were recorded to have returned to Maine’s rivers in 2002. The serious depletion of salmon populations in Maine underscores the need to expand rehabilitation efforts to as many of Maine’s rivers as possible. Since most Maine salmon are now in the Penobscot River, that population should be a primary focus for rehabilitating the species in Maine. The committee recommends the following urgent actions: A program of dam removal should be started. Priority should be given to dams whose removal would make the greatest amount of spawning and rearing habitat available, which means that downstream dams generally should be considered for removal before dams upstream of them. In some cases, habitat restoration will likely be required to reverse or mitigate some habitat changes caused by the dam, especially if the dam is many decades old. A recent agreement to remove two Penobscot River dams is encouraging. The problem of early mortality as smolts transition from freshwater to the ocean and take up residence as post-smolts needs to be solved. If, as seems likely, early mortality in estuaries and the ocean is due in part to water chemistry, particularly acidification in freshwater, the only methods of solving the problem are changing the water chemistry and finding a way for the smolts to bypass the dangerous water. Liming has had considerable success in counteracting acidification in many streams, and the techniques are well known. Examples of its application are in nearby Nova Scotia. Liming should be tried experimentally on some Maine streams as soon as possible. Bypassing the dangerous water is best achieved by rearing smolts and acclimating them to seawater in controlled conditions. This approach is not appealing because of the degree of human intervention required and because of the adverse selection that must result from it. Given the extreme depletion of salmon populations, however, desperate measures are needed.

OCR for page 1
Atlantic Salmon in Maine Hatcheries need to continue to be used, at least in the short term, to supplement wild populations and to serve as a storehouse of fish from the various rivers. There is an urgent need to understand the relative efficiency of stocking of different life stages in the rivers in terms of adult returns per brood-stock fish and their reproductive success. Additional research on hatcheries and scientific guidance for their use is needed, because hatchery-based restoration of wild salmon populations remains an unproven technology. The committee was asked to provide estimates of the approximate relative costs of the various options. Although it has not been able to provide detailed cost estimates for all of its recommendation, it does estimate that dam removal would cost between $300,000 and $15 million per year; and liming would cost on the order of $100,000 per stream initially plus $50,000–$100,000 per year. The cost of changing hatchery operations as recommended would not require major additional expenditures beyond what is currently spent on federal hatchery operations for Atlantic salmon in Maine. Although the costs of changes to salmon farming cannot be reliably estimated, it is clear that most of the modifications would likely cost enough to eliminate the profitability of salmon farm operations. Actions Important over the Longer Term Over the longer term, the committee recommends a comprehensive decision-analysis approach to the rehabilitation of Atlantic salmon populations in Maine. The analysis should be conducted along the lines of the examples in Chapter 5 of this report but in more detail and with all major groups of stakeholders involved. Taking a Maine-wide view is more likely to be successful than focusing only on some rivers. No anadromous Atlantic salmon of any life stage should be stocked in rivers that have populations of wild Atlantic salmon unless those rivers are specifically identified as part of a hatchery-recovery program that uses river-specific stocks (that is, a program that takes brood stock from the river to be stocked with the aim of retaining any local genetic differentiation). Stocking of nonnative fish species and landlocked salmon also should be avoided in those rivers. Other rivers that once supported wild Atlantic salmon runs, but which lack them now, will probably become repopulated by strays from nearby streams if populations in those nearby streams recover. The advantages of such natural repopulation, which would be more likely than stocking to lead to local genetic adaptation, should be given serious attention before any decision is made to stock streams that currently lack wild Atlantic salmon runs.

OCR for page 1
Atlantic Salmon in Maine The current prohibition of commercial and recreational fishing for salmon in Maine, including catch-and-release fishing, should be continued. Any further reduction in the take of Maine salmon at sea would be helpful. Maximum and minimum size limits for trout and landlocked salmon should be established in rivers that have anadromous Atlantic salmon. The minimum size for retention should be large enough to protect Atlantic salmon smolts, and the maximum size should be small enough to protect adult Atlantic salmon. Any fishing that might take a wild Atlantic salmon, even inadvertently, constitutes an additional risk to the species. This risk should be carefully evaluated for all Maine rivers with Atlantic salmon, and additional measures should be taken if the risk is judged to be important. Habitat zones most heavily used by Atlantic salmon young and adults should be closed to fishing for all species until salmon populations have recovered. Research that increases the risk of death to wild fish should be curtailed. The value of any information obtained needs to be weighed against the likelihood of increased death of wild fish subjected to handling. Every effort should be made to further curtail the escape of salmon from farms. If accumulation of parasitic copepods (sea lice) or other pathogens is found to be a problem for wild salmon, the aquaculture facilities should be moved to a place where they will not adversely affect wild salmon. Hatchery practices should be evaluated in an adaptive-management context to further reduce adverse genetic and ecological effects and modified as needed. The monitoring of water quality and gauging of streams should be augmented. A network of metereological-monitoring, stream-gauging, water-quality-monitoring, and biological-monitoring sites should be linked to a geographic information system and an online database within 2 years. Government, industry, and private organizations and landowners should cooperate to evaluate forestry best-management practices and forest-road networks. Mitigation and pollution prevention should be organized to maximize the effectiveness of storm-water management and sediment control and the removal of barriers to fish passage. The State Planning Office should conduct a systematic governance assessment to see whether there are gaps in authority, overlapping authority, conflicts of goals and interests among agencies, and adequate cooperation among agencies. The State Planning Office, in cooperation with all other agencies, should implement adaptive management to monitor performance of governance activities related to Atlantic salmon, to experiment with alterna-

OCR for page 1
Atlantic Salmon in Maine tive institutions for salmon recovery, and to systematically learn and adapt to the results of new information. The Maine Atlantic Salmon Commission should consider shaping governance structures so that they are consistent with salmon biology. That process could involve developing multistakeholder governance institutions for each drainage basin, each nested within larger scale governance bodies to address effects that are larger than individual basins, such as climate change and aquaculture. The suite of additional options with multiple environmental benefits outlined in Chapter 5 should be adopted. Those strategies are likely to help Atlantic salmon in Maine, and they will have other environmental benefits even if they do not help salmon. The energy and commitment of the members of many local watershed and river-specific groups focused on restoring salmon and their habitats is an important asset and should be included in any overall approach to rehabilitating Atlantic salmon and their habitats in Maine.