1
Introduction

BACKGROUND

Maine was once the home of abundant populations of wild Atlantic salmon (Salmo salar), but they have been declining since at least the middle of the nineteenth century (Baum 1997). Despite conservation efforts over the past 130 years or so, populations in Maine have continued to decline, and now they are seriously depleted in all the rivers that still retain natural runs. Only an estimated 862 adult salmon returned to Maine streams to spawn in 2002, down from 940 in 2001 (MASC 2002). Most of those fish returned to one river, the Penobscot (782 in 2002 and 786 in 2001). The declines led to the listing of Atlantic salmon in eight Maine rivers (Cove Brook, Dennys, Ducktrap, East Machias, Machias, Narraguagus, Pleasant, and Sheepscot) as an endangered distinct population segment (DPS) under the federal Endangered Species Act (ESA) by the Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS) on November 17, 2000 (50 CFR 17, 224). Figure 1-1 and Table 1-1 show New England rivers with Atlantic salmon; the eight so-called DPS rivers are identified. Those eight rivers together had minimum estimates of 64 returning adults in 2000, 81 in 2001, and 33 in 2002 (MASC 2002, USASAC 2003). In 2002, no returning adults or redds were observed in Cove Brook, the Ducktrap River, and the Pleasant River.



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Atlantic Salmon in Maine 1 Introduction BACKGROUND Maine was once the home of abundant populations of wild Atlantic salmon (Salmo salar), but they have been declining since at least the middle of the nineteenth century (Baum 1997). Despite conservation efforts over the past 130 years or so, populations in Maine have continued to decline, and now they are seriously depleted in all the rivers that still retain natural runs. Only an estimated 862 adult salmon returned to Maine streams to spawn in 2002, down from 940 in 2001 (MASC 2002). Most of those fish returned to one river, the Penobscot (782 in 2002 and 786 in 2001). The declines led to the listing of Atlantic salmon in eight Maine rivers (Cove Brook, Dennys, Ducktrap, East Machias, Machias, Narraguagus, Pleasant, and Sheepscot) as an endangered distinct population segment (DPS) under the federal Endangered Species Act (ESA) by the Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS) on November 17, 2000 (50 CFR 17, 224). Figure 1-1 and Table 1-1 show New England rivers with Atlantic salmon; the eight so-called DPS rivers are identified. Those eight rivers together had minimum estimates of 64 returning adults in 2000, 81 in 2001, and 33 in 2002 (MASC 2002, USASAC 2003). In 2002, no returning adults or redds were observed in Cove Brook, the Ducktrap River, and the Pleasant River.

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Atlantic Salmon in Maine FIGURE 1-1 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.

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Atlantic Salmon in Maine TABLE 1-1 Inventory of Current U.S. Atlantic Salmon Rivers No. River States Length (km) Drainage Area (sq ha) 1 Aroostook ME 115 5,931 2 Prestile Stream ME 39 562 3 Meduxnekeag ME 65 1,287 4 Saint Croix ME 50 6,475 5 Dennysd ME 32 342 6 East Machiasd ME 59 650 7 Machiasd ME 98 1,191 8 Pleasantd ME 45 220 9 Narraguagusd ME 78 601 10 Tunk Stream ME 27 104 11 Union ME 100 1,295 12 Penobscote ME 267 22,196 13 Ducktrapd ME 17 93 14 Sheepscotd ME 55 591 15 Kennebec ME 242 15,540 16 Androscoggin ME 207 6,475 17 Saco ME and NH 201 4,395 18 Cocheco NH 70 479 19 Lamprey NH 100 500 20 Merrimack MA and NH 302 12,976 21 Pawcatuck RI     22 Connecticut CT, MA, VT and NH 667 29,138 TOTAL     2,836 111,041 aAtlantic salmon habitat is defined as riffles and runs. bData based upon surveys in 1950s–1960s; a + indicates that some tributaries (mostly minor) have not been surveyed. cNorth Atlantic Salmon Conservation Organization (NASCO) categories: L, lost; M, maintained; R, restored; T, threatened with loss; N, not threatened with loss. U indicates current population status unknown. dAtlantic salmon populations in these rivers listed as endangered under the federal Endangered Species Act.

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Atlantic Salmon in Maine Atlantic Salmon Habitat Unitsa (unit = 100 sq mi)   Surveyed Amount Estimated Amountb Total Amount (minimum) Salmon Population Statusc 30,000 30,775 60,775 L – 835 835 U – 10,000 10,000 U 29,260 + 29,260 L 2,414 + 2,414 T 3,006 + 3,006 T 6,156 + 6,156 T 1,220 + 1,220 T 6,014 + 6,014 T – 627 627 L – 8,370 8,370 L – 125,000 125,000 Tf 845 + 845 T 2,797 + 2,797 T 43,483 114,300 157,783 Tf – 47,900 47,900 L 12,540 15,000 27,540 L   + 0 L   + 0 L   + 0 L 4,490 + 4,490 L 243,000 + 243,000 L 385,225 352,807 738,032   eCove Brook, a tributary to the lower Penobscot River, is one of the eight rivers identified in footnote 1 above. fDesignation applies to selected tributaries below the first hydrodam. Abbreviations: sq mi, square mile; km, kilometer; sq ha, square hectare. SOURCE: Adapted from NASCO Special Session on Salmon Habitat, Faroe Islands, June 2002.

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Atlantic Salmon in Maine No one disputes the general seriousness of the declines, but many people in Maine claim that the populations are not wild1 and, therefore, oppose the ESA listing. They argue that the fish are derived mainly from hatchery stocking and aquaculture escapes. If so, then appropriate measures to increase the number of salmon in Maine’s rivers could be quite different from appropriate measures to increase wild salmon runs in those rivers. The controversy led Congress to mandate a study of Atlantic salmon in Maine by the National Research Council (NRC). An interim report was to be prepared in time to help any recovery efforts (see Box S-1 for committee’s statement of task). The interim report (NRC 2002a) by the NRC Committee on Atlantic Salmon in Maine focused on the genetic characteristics of the wild populations in Maine, especially in the listed rivers. In this report, the committee focuses on the broader issues contributing to the decline of salmon in Maine and options for helping them to recover. THE LISTING OF SALMON UNDER THE ENDANGERED SPECIES ACT The ESA of 1973, as amended in 1988 (Public Law 100-478), defines species as including “any subspecies of fish or wildlife or plants, and any distinct population segment of any species o[f] vertebrate fish or wildlife which interbreeds when mature” (Section 3 {15}). A detailed description of the ESA’s provisions as they affect Atlantic salmon in Maine is in Appendix C. The salmon in the eight Maine rivers, including “all naturally reproducing wild populations and those river-specific hatchery populations of Atlantic salmon having historical, river-specific characteristics found north of and including tributaries of the lower Kennebec River to, but not including, the mouth of the St. Croix River at the U.S.-Canada border,” were listed as an endangered DPS by FWS and NMFS (“the Services”) on November 17, 2000 (65 Fed. Reg. 69459 [2000]). The eight rivers are often referred to as the DPS rivers. The science that underlies the ESA; the concept of species, including subspecies and DPSs; and 1   The term wild is used by the committee to mean populations of salmon that have been maintained by natural spawning for at least two full generations. This practical definition is used by the committee to distinguish salmon populations that are supported by human activities (hatchery fish) from those that have established themselves in the wild. The committee agrees with Baum (1997) that pristine salmon populations that have always been wild with no human influences on their genetic makeup almost surely do not exist in Maine. The term natural is used for salmon populations that are derived from parents’ reproduction in streams rather than stocking.

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Atlantic Salmon in Maine the meaning of “endangered” under the ESA are discussed in considerable detail in two earlier NRC reports (NRC 1995, 1996a). THE PRESENT STUDY AND REPORT ORGANIZATION For this study, the committee met three times in Maine and heard presentations from representatives of the state government of Maine, including Governor Angus King; from the Services; from the Atlantic Salmon Commission; and from a variety of industrial, academic, environmental, and other private organizations and individuals. The committee also visited an Atlantic salmon farm and two blueberry farms in Washington County, a weir on the Pleasant River, the federal hatchery at Craig Brook, the site of the former Edwards Dam on the Kennebec River, road crossings over salmon streams, and other sites. Lists of the presenters and facilities visited are in the front matter. The committee met once each in Boston and Woods Hole, Massachusetts, and once in Washington, D.C., and considered an array of published literature and reports. The committee has attempted to bring a new perspective to this muchstudied problem. There is no lack of factors known to have adversely affected Atlantic salmon in Maine and throughout their historical range in eastern North America. Indeed, the problem is that too many such factors are known, and the difficulty is how to prioritize them and how consequently to prioritize potential actions to rehabilitate2 the salmon populations and their environments. The committee has taken a risk-assessment and decision-analysis approach, in part for illustrative purposes but also to help it assess the importance of the factors affecting salmon and to prioritize potential rehabilitation options. The committee also considered the entire state as potentially available for rehabilitation efforts, rather than only the eight DPS rivers. As a result, our focus is much broader than only the requirements of the ESA. The committee’s work along these lines is only a beginning, but we hope that by following the example and guidance in this report, decisions and actions taken by those responsible for and interested in rehabilitation of salmon populations in Maine will be made more productive and effective. The report begins with a description of Atlantic salmon in Maine and the environments they inhabit (Chapter 2). Chapter 3 describes the most significant threats to salmon in Maine. The committee then describes risk 2   Following the usage of the NRC Committee on Protection and Management of Pacific Northwest Anadromous Salmonids (NRC 1996a), the committee has chosen to consider rehabilitation as a practical and achievable strategy, rather than restoration, which implies return of ecosystems to some previous but unknowable pristine condition.

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Atlantic Salmon in Maine assessment and decision analysis and the committee’s Atlantic salmon risk model in some detail (Chapter 4). Chapter 4 also discusses the committee’s decision analyses for dams and for salmon farms; they are provided as examples of how to think about such issues systematically but not as a substitute for such analyses by the people who have to live with the results. Chapter 5 discusses methods of addressing the threats to Atlantic salmon in Maine, and Chapter 6 provides the committee’s findings and recommendations.