Atlantic Salmon ( Salmo salar) imperilment in North Eastern United States

1. Atlantic Salmon (Salmo salar) imperilment in North Eastern United States Natural Resources and Environmental Science, Illinois Natural History Survey and the Department of Law at the University of Illinois Champaign, IL 2008 Atlantic Salmon (Salmo salar) Imperilment in the North Eastern United States Learning Module prepared by: Andrew Gingerich

2. TABLE OF CONTENTS • Description of the Conservation Issue • Background and History • Science and Research • Conflicts and Debate • Relevant Legislation • Legislative Effectiveness • Resources • References • Glossary • Appendix

3. Summary Atlantic Salmon (A.S.) are a fish species native to the Northeastern and Northwestern coasts of the Atlantic Ocean. This Anadromous fish species spends 1–3 years in freshwater rivers before moving to sea, traveling to the coast of Greenland and feeding for an additional 1–3 years. During this marine growth period, fish become reproductively mature and return to native rivers to spawn. Most fish spawn and die, but some are iteroparous, having the ability to “drop-back” or return to sea, before having another freshwater spawning bout. In Maine and much of the New England coast, the US Fish and Wildlife listed this species under the Endangered Species Act due to significant decreases in returning salmon. Historically more than 500,000 fish returned to these rivers. However, estimates over the last few years remain at a low of around 2000 fish. In Maine, research has shown that a Distinct Population Segment (DPS) of fish exist, having novel life history traits. These DPS fish are at critically low numbers in recent years, having only about 33 estimated fish return to 8 rivers in Maine (2002). Many factors are thought to be responsible for this decline, including, but not limited to, dams, poor stocking practices, air pollution, habitat degradation, invasive species introduction, and marine mortality. Stakeholders have interest in restoring this species to New England. The Endangered Species Act, Clean Water Act, Magnuson-Stevens Act and the Coastal Zone Management Act have relevant application and legislative involvement in the Atlantic Salmon issue in the Northeastern United States.

4. Summary Atlantic Salmon (A.S.) are a fish species native to the North Eastern and North Western coasts of the Atlantic Ocean. This Anadromous fish species spends 1-3 years in freshwater rivers before moving to sea, traveling to the coast of Greenland and feeding for an additional 1-3 years. During this marine growth period fish become reproductively mature and return to native rivers to spawn. Most fish spawn and die but few are iteroparous, having the ability to “drop-back” or return to sea, before having another freshwater spawning bout. In Maine and much of the New England coast the US Fish and Wildlife listed this species under the endangered species act due to significant decreases in returning salmon. Historically more than 500 000 fish returned to these rivers. However, estimates over the last few years remain low around 2000 fish. In Maine, research has shown that a distinct population segment (DPS) of fish exist, having novel life history traits. These DPS fish are at critically low numbers in recent years having only about 33 estimated fish return to 8 rivers in Maine (2002). Many factors are thought to be responsible for their decline including, but not limited to dams, pour stocking practices, air pollution, habitat degradation invasive species introduction, and marine mortality. Stake holders have interest in restoring this species to New England. The ESA (endangered species act), Clean water act, Magnuson-Stevens Act and the Coastal Zone Management have relevant application and legislative involvement in the Atlantic salmon issue in the North Eastern United states. What do these words mean? Throughout this module you might find words that you do not understand. The glossary at the end of the module can help explain these terms. View Glossary Now Please

5. Description of the Conservation Issue • Atlantic Salmon have been declining all over their native range since the 1800s and perhaps even before • Managers and stakeholders are interested in restoring many native populations • Much is know about their natural history, but little conclusive answers have been given in how to stop the decline and restore populations At left are two Atlantic salmon spawning in a shallow water stream. Notice the gavel substrate, or bottom, on which they spawn. This kind of habitat is crucial for Atlantic Salmon spawning. Photo credit: Fish Base

6. Atlantic Salmon Historically in Maine • In the early 1800s, half a million adult Atlantic Salmon were returning to US rivers annually. • In 2001, the estimate was 1,050 returning fish. • 780 (90%) of which returned to only one river in Maine called the Penobscot (#9 on the figure to the right). • In 2002, 871 estimate returned). • In November 2000, US Fish &Wildlife listed Atlantic Salmon as endangered (ESA). • Returns in 2007 were estimated at 940 salmon; that number more than doubled in 2008 with estimates at 2,000 salmon returns. • Still, that’s less than 0.5% of the original number of returning fish.

7. Atlantic Salmon Declines in Maine • The Gulf of Maine Distinct Population Segment (DPS) has declined to critically low levels. More will be explained about DPS fish throughout this learning module. • No DPS adults were documented in three of the eight DPS rivers. • Despite fry stocking, smolt production continues to drop: From 1996 through 1999, annual smolt production in the Narraguagus River was estimated to average about 3,000. Smolt production declined significantly in 2000 and has averaged only about 1,500 fish per year (half of the annual production from 1996 – 1999). • Since 1997, overwinter survival of juvenile Atlantic Salmon in the Narraguagus River has averaged only about 12%, approximately half of the survival rate of previous years.

8. Why Have Atlantic Salmon Declines Happened?Atlantic Salmon declines happen because return and replacement rates are decreasing Return rates of Atlantic Salmon to Maine’s River (both DPS and other Atlantic Salmon) and replacement rates for adult salmon have been decreasing since 1967 and earlier. If adult salmon do not at least replace themselves with one offspring, the population declines. The figure below shows a replacement rate of less than 1.0 between 1996 and 2002.

9. Atlantic Salmon Life History Leave for the ocean Return from the Ocean mature

10. At 10 – 13 cm, smoltification takes place (5 inches). After this, smolts migrate to the open ocean. An average of 50 % of smolts die because of the physiological stress associated with moving from fresh to salt water. Juvenile Atlantic Salmon remain in freshwater 1 – 3 years and develop as parr. They feed primary on macroinvertabrates or small aquatic bugs. Salmon migrate to Greenland, where they spend 1 – 3 years feeding and growing before returning in the fall to spawn in the same location from which they hatched. In Maine reproductive site fidelity is greater the 98 %. Mature Atlantic Salmon spawn in the fall. Eggs remain in substrate over winter and hatch in the spring. http://www.nefsc.noaa.gov/sos/spsyn/af/salmon

11. Atlantic Salmon Natural History Females returning to spawn, after spending two winters at sea, will lay an average of 7,500 eggs. • About 15 – 35% will survive to the fry stage. (NOAA) • About 1.25% of eggs make it to the smolt stage (90 smolts per female). • Of smolts, there is a 50% mortality rate as they move from fresh to salt water. Most spawning adults die after spawning, but some are iteroparious (1 – 6%) and drop back to sea, only to return to the rivers and spawn again. Photo Caption: Atlantic salmon migrating up spawning rivers (Credit: National Geographic)

12. Distinct Population Segment The map below shows a part of Maine where the significant population of Atlantic Salmon exists. 8 Rivers in Maine have fish in them that make up a Distinct Population Segment (DPS). In 2002, only 33 estimated salmon returned to those rivers. What is a DPS? A DPS is a group of animals within a species that have unique life history traits due to novel genetics. Because of these unique traits, they are considered to be of great importance for the genetic conservation of a species.

13. Distinct Population Segment The 8 rivers that the DPS fish return to are Dennys, Machias, east machias, Pleasant, Narraguagus, Ducktrao, Cove Brook, Sheepscot and are bolded in this diagram. What Makes These Fish a Distinct Population Segment? In 1999, scientists completed a status review and concluded that the Gulf of Maine Distinct Population Segment (DPS) has unique life history characteristics that are heritable (i.e., can be passed on to offspring). These life history features include timing of spawning runs and growth rates. The National Research Council Committee on Atlantic Salmon in Maine determined that the large genetic differences among populations suggest biologically important genetic isolation has occurred in these fish. Furthermore, genetic differences among tributaries within large watersheds are suggestive of local adaptations though evolutionary processes. Therefore, since the traits are novel relative to other global stock, there is a necessity to conserve this Distinct Population Segment.

14. Why Are Atlantic Salmon Imperilled ? • Marine Mortality –High percentage of fish die at sea. • Dams – Adult and juvenile obstruction, water quality. • Hatcheries – No attention to genetics; not clear how invasive this is. • Aquaculture – Pens transmit disease; parasites concentrated. • Acid Deposition –Sulphates and other airborne chemicals led to the extirpation of Atlantic Salmon in more the 12 rivers in Nova Scotia. Particularly bad in young fish. • Fishing –By 2000, all harvest and C&R was stopped in Maine. By 2002, commercial fishing almost complete eliminated at sea. • Changes in Atmospheric and Ocean Climate –Warming waters because of warming climate (increased over the last 30 years in Maine). • Predation and Food Supply – Is natural but has gotten worse because of non-native piscivorous fish. Plus human selection and protection has altered food supplies and predation risk (i.e., Marie Mammal Protection Act). • Governance – Gap between government structure and Resource Management knowledge, stakeholders, etc.

15. ISSUES: # 1 Marine mortality • One of the biggest conerns is the high rate or morality at sea. Understanding why marine mortality occurs is challenging for a number or reasons: • Most return rate data does no distinguish between losses occurring shortly after emigration to the sea and those occurring on the high seas. - A lot can happen during 1 – 3 years at sea. - High seas fishing has been virtually eliminated, thus no data is collected by commercial fishing observers and therefore the sex, size, location and other indices are not determined at sea. -Mortality is likely due to water temperature, food availability and predation.

16. ISSUES: # 2 DAMS In the past, dams placed on Maine’s rivers for mills and other purposes caused problems for the Atlantic Salmon. Juvenile salmon (smolts) would die as a result of traveling through turbines within dams en route to sea. In addition, the dans prevented passage of adults upstream to spawning locations. Fish ways have improved these issues, but dams still create a number of problems for salmon, including: • Cormorants select foraging areas adjacent to dams because of the higher availability of prey than other parts of rivers. This is likely due to delay and injury of migrating Atlantic Salmon smolts. • Striped bass, an Atlantic Salmon predator, also congregate by dams waiting for confused, injured and vulnerable AS smolts, which can make up to 80% of a striped bass diet. • Finally, dams can change the water temperature and quality of downstream

17. ISSUES: # 3 & 4 hatcheries & aquaculture • Stocking in Maine began in 1870, and the first young obtained were from lake Ontario. • Because of the lack of concern for genetics, lots of genetic mixing of Canadian Stocks and European Stocks occurred. • Between 1871 and 1886, about 24 million eggs were taken from wild Penobscot sea-run salmon. Most of these eggs were used to stock waters outside of the Distinct Population Segment area, including in-land lakes, to create or enhance landlocked salmon populations. • In the 1920s and 1930s, Canadian stocks were used to stock Atlantic Salmon in Maine. • Despite this mixing in 2002, researchers concluded that North American Atlantic Salmon are genetically distinct from European Atlantic Salmon. • Despite stocking mixed genotypes, Maine still has Atlantic Salmon that are distinct from Canadian. Still, wild salmon in Maine DPS rivers are genetically different from European and Canadian Atlantic salmon. More specifically... U.S. Atlantic salmon stocks are composed of predominately adults that spend two winters at sea before returning (2SW ) (> 80%), while generally Canadian and European stocks have a much higher grilse (one winter at sea adults) component and a lower 2SW component (often <50%). The proportion of 2SW fish in an Atlantic salmon stock has a documented genetic basis.

18. ISSUES: # 5 Acid deposition and water pollution • Smolt survival is affected by a restricted readiness time, sometimes referred to a physiological “smolt window,” and the timing of seawater entry with environmental conditions such as temperature, food, and predators, or an ecological “environmental window.” • Smolt development is adversely affected by acidity, pollutants, and improper rearing conditions, and unfortunately smolts are often more sensitive than they would be at other life stages. • Unfortunately, the migration corridor of smolts are the most heavily impacted by pollution and other anthropogenic activities that may be directly lethal or increase mortality by delaying or inhibiting smolt migration.

19. ISSUES: # 6 Fishing- Commercial and recreational • In the 1950s, it was discovered that salmon from rivers in the US and Canada, as well as from Europe, gathered in the sea around Greenland and the Faroe Islands. Because of this, massive commercial fishing was established. After an initial series of record annual catches, the numbers crashed — between 1979 and 1990, catches fell from four million to 700,000. • Until recently, the West Greenland fishery was one of the last directed Atlantic Salmon fisheries in the Northwest Atlantic. Commercial fishing for Atlantic Salmon within Greenland territorial waters was suspended for five years in 2002. However, some internal-use fishery continues. • The internal-use fishery is a mixed stock fishery, catching both North American and European fish. Maine-origin salmon, including endangered salmon, are taken in low numbers. Based upon tag returns, the commercial fisheries of Newfoundland and Labrador historically intercepted far greater number of Maine-origin salmon than the West Greenland fishery. However, concerns exist about the potential of the West Greenland fishery to harvest endangered U.S. salmon.

20. ISSUES: # 6 Fishing- Commercial and recreational Cont’d • It has been well established that even recreational fisheries, both catch-and-keep and catch-and-release fishing, can be harmful to fish stocks. • Once these fish were listed to the ESA and declines were made apparent, recreational fishing for Atlantic Salmon was discontinued in the Northeastern United States. Maine recently opened a short period of catch-and-release fishing that is meant to be experimental. See the guidelines below: 1.02 Size and Bag Limits Fishing for anadromous Atlantic Salmon (Salmo salar) is prohibited statewide, except as provided in section 1.03. Any anadromous Atlantic salmon caught incidentally to other angling shall be released alive immediately without removal from the water. 1.03 Experimental Open Season 1. Time Period There will be a limited, experimental open season for directed angling for Atlantic salmon from May 1, 2008 to May 31, 2008 on the Penobscot River in the area specified below. 2. Open Area Penobscot River; Between two painted red markers placed on opposing banks that are 150 feet below the Veazie Dam fishway, down river to the former site of the Bangor Dam, which will also be marked by two painted red markers. The open area does not include the pool below the former dam site. 3. Conditions Include Catch -and-release only;no fish may be taken out of the water for any reason; and only fly fishing may be used as a method of capture while using barbless hooks.

21. ISSUES: # 7 changes in atmospheric and Ocean Climate Research has shown that surface ocean water temperatures have an impact on the quality and numbers of adult salmon returning to spawn in rivers. Specifically, sea surface temperature distributions for periods of high versus low return rate showed: • When low sea surface temperatures dominate the North Sea and Southern coast of Norway during the month of May, salmon survival decreases. • Conversely, when high sea surface temperatures extend northward along the Norwegian coast during the month of May, survival is favorable. It’s unclear how Atlantic Salmon will be impacted or have been impacted by global climate change. However, streams in Maine have significantly increased water temperatures over the past few decades and this is considered to be troubling information for spawning adult and young Atlantic Salmon. These are recently hatched salmon, sometimes referred to as egg sac fry or egg sac salmon. They use their yolk sacs as food for about a week before they can feed on their own.

22. ISSUES: # 8 Predation • Community assemblages in Atlantic Salmon streams have changed in recent years. Brown trout and largemouth, smallmouth and striped bass have been added to Atlantic Salmon streams and rivers in the Northeastern US. All are piscivorous, or eat other fish, including young Atlantic Salmon. • In addition, many of these species compete with Atlantic Salmon for resources or eat their eggs. • Protection afforded to marine mammals and birds, predation on Atlantic Salmon is likely higher than it was during higher return rates in the 1970s (e.g., Cormorants are protected and significant predators of smolts). The Brown trout (left) looks a little bit like an Atlantic Salmon (AS), but it is another fish species that competes with Atlantics, in addition to eating AS offspring. The largemouth bass (right ) is another piscivorous fish species that was introduced to historical AS streams recently.

23. ISSUES: # 9Governance • Often, economics and conservation do not match up. • With the Atlantic Salmon (AS) issue, many people are involved, including AS farmers, anglers, commercial anglers, states, and perhaps even the conservation of the fish species in general. • Each one of the above mention groups needs different things when it comes to AS. • For example, Atlantic Salmon in Maine need genetic diversity conservation, which means eliminating hatchery and aquaculture escapees, while farmers of Atlantic Salmon need increased efficiency in production and decreased operation costs. Thus famers favor narrow genetics, or fish that put on weight and do well under hatchery conditions, not necessary increased genetic diversity and strong genetic traits that lead to high survival in the wild.

24. Conflicts and Debate Conflict: • Atlantic Salmon remains a popular fish for human consumption. It is commonly sold fresh, canned, or frozen. However, these consumed fish come from farming, which can have adverse effect on natural AS recovery. • There is little debate regarding AS imperilment. Where the debate exists is if the Distinct Population Segment (DPS) still exists or are they all stocked out fish. • Some anglers believe they should be able to capture and keep DPS fish because they believe that these fish are no longer natural fish. Stakeholders: • Commercial Fisherman/Aquaculture — In 1998, the value of Maine aquaculture products was estimated at nearly $70 million. Atlantic Salmon accounts for over 90% of this value ($68 million). Employs over 1000 people. Issue: Fish get out and eutrophication. • Catch-and-release anglers • Consumers • States: Significant state revenue can be generated with healthy fish Atlantic Salmon stocks due to commercial and recreational significance of this species.

25. Relevant Legislation in the United States Costal Zone Management Act — In 2002 and 2003, Maine received 2.5 million from the Federal government, which the state matched. This money helps to develop riparian and shoreline habitat, but is not necessarily aimed directly at Atlantic Salmon recovery. Endangered Species Act — Section 9 of the Endangedred Species Act (ESA) prohibits the take of the endangered Atlantic Salmon. The term “take” means to “harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or attempt to engage in any such conduct.” Clean Water Act — This Act prohibits pollution that is generated by Atlantic Salmon farming, but net pen farming violates the CWA and ESA current regulations.

26. Relevant Legislation in the United States The ESA not only protects Atlantic Salmon as a species, but also critical habitat of the species. The ESA defines critical habitat as: (i) the specific areas within the geographical area occupied by the species, at the time it is listed in accordance with the [Act], on which are found those physical or biological features (I) essential to the conservation of the species and (II) which may require special management considerations or protection; and (ii) specific areas outside the geographical area occupied by the species at the time it is listed in accordance with the provisions of section 1533 of this title, upon a determination by the Secretary that such areas are essential for the conservation of the species.

27. Legislation (continued): Canada • In May 2001, Atlantic salmon populations in several rivers in the upper Bay of Fundy were designated as endangered by the Canadian Committee on the Status of Endangered Wildlife (COSEWIC). • The Species at Risk Act (SARA) was passed in October 2002. The Atlantic Salmon Inner Bay of Fundy populations are protected under SARA. Canada: Inner Bay of Fundy Atlantic Salmon runs were declared endangered in 2000. • A new Atlantic Salmon Policy is being developed, but as of 2008, no recovery plan is in place. • Recreational fishing for Atlantic Salmon is not prohibited. For example, in the province of Quebec, the daily catch limit for Atlantic salmon is one fish over 63 cm, two fish under 63 cm, or one fish over and one under 63 cm, provided that the smaller fish was the first one caught (a provision designed to prevent an angler from continuing to fish if a large fish is already in possession). The annual catch limit is seven Atlantic Salmon of any size.

28. Legislation (continued): International Support The North Atlantic Salmon Conservation Organization (NASCO) is an international council made up of Canada, Denmark, the European Union, Iceland, Norway, the Russian Federation, and the United States, with its headquarters in Edinburgh. It was established in 1983 to help protect Atlantic Salmon stocks. More information about this organization can be found at NASCO ~ North Atlantic Salmon Conservation Organisation. Simply click the link (you will need an internet connection).

29. Success? Some are not convinced and think that the federal government isn’t doing enough, including allowing aquaculture violate the ESA’s definition of harm through pollution and the CWA’s definition of pollution. • In New England, many efforts are underway to restore Atlantic Salmon to the region by knocking down obsolete dams and updating others with fish ladders and other contraptions that have proven effective in the West with Pacific Salmon. • There has been some success thus far, with populations growing in the Penobscot River and the Connecticut River. • In Ontario, the Atlantic Salmon Restoration Program was started in 2006, and it is one of the largest freshwater conservation programs in North America. It has stocked Lake Ontario with over 700,000 young Atlantic Salmon. In November 2007, a migrating salmon was observed in the Credit River.[10] There has also been some success in establishing Atlantic salmon in Fish Creek, a tributary of Oneida Lake in Central New York. Excerpt from the article at right: “net pen facilities in Maine are in violation of both the Federal Water Pollution Control Act (Clean Water Act or CWA) and the Endangered Species Act (ESA)... this Note argues that the recent, proposed CWA Federal effluent guidelines briefly set forth above would serve not only as an extremely low baseline for state regulation, but would also contravene the purposes of the CWA while stifling implementation of the ESA as applied to the endangered, wild Atlantic Salmon.”

30. Conclusions • Atlantic Salmon are an important species in Maine and all over the North Atlantic Coast and Ocean. • Recently they have been declining in numbers. • There are a number of reasons responsible for these declines. • Maine importantly has some genetically unique Atlantic Salmon know as the DPS fish. • The conservation of the DPS fish is important for maintaining the genetic diversity of this fish species on a global scale. • A number of relevant acts, laws and legislatures have been designed to help strengthen Atlantic Salmon numbers worldwide, specifically along the Northeastern coast of Maine.

31. THE END OF THE LEARNING MODULE • END of Learning Module

32. RESOURCES Additional reading can be found in the following articles: Simply put this title in an Internet browser search engine (Google, Yahoo, etc.). Theses documents are free to the public.

33. REFERENCES • Atkins, C. G. (1874). On the salmon of eastern North America, and its artificial culture. P. 227-335 in United States Commission of Fish and Fisheries Report of the Commissioner for 1872 and 1873, part II. Washington. • Baum, E. (1997). Maine Atlantic Salmon: A National Treasure. Atlantic Salmon Unlimited, Hermon, ME. • Blackwell, B.F. and F. Juanes. (1998). Predation on Atlantic Salmon Smolts by Striped Bass after Dam Passage. North American Journal of Fisheries Management 18: 936–939. • Blackwell, B.F. and W.B. Krohn. (1997). Spring foraging distribution and habitat selection by double-crested cormorants on the Penobscot River, Maine USA. Colonial Waterbirds 20(1): 66-76. • Boschung, H.T. (1983). The Audubon Society Field Guide to North American Fishes, Whales & Dolphins. Chanticleer Press.  • Department of Maine Resources. Atlantic salmon fishing regulations pdf file. <http://www.maine.gov/dmr/searunfish/fishing.htm> Department of Marine Resources State of Maine. • Friedland, K.D. (1998). Ocean climate influences on critical Atlantic salmon (Salmo salar) life history events. Can. J. Fish. Aquat. Sci. 55(S1): 119–130.   • Friedland, K.D., L.P. Hansen, D.A. Dunkley, and J.C. MacLean. (2000). Linkage between ocean climate, post-smolt growth, and survival of Atlantic salmon (Salmo salar L.) in the North Sea area. ICES Journal of Marine Science 57(2): 419-429 . • Glebe, B.D., and R.L. Saunders. (1986). Genetic factors in sexual maturity of cultured Atlantic salmon (Salmo salar) parr and adults reared in sea cages. Salmonid Age At Maturity., Can. Spec. Publ. Fish. Aquat. Sci. No. 89 : 24-29. • Harb, M. (June 2008). Upstream Battle. Canadian Geographic Magazine. • Hutchings, J.A., and M.E.B. Jones. (1998). Life history variation and growth rate thresholds for maturity in Atlantic salmon, Salmo salar. Canadian Journal of Fisheries and Aquatic Sciences 55 (suppl.1): 22-47. • Kendall, W. C. (1935). The fishes of New England: the salmon family. Part 2 – the salmons. Memoirs of the Boston Society of Natural History: monographs on the natural history of New England. Vol. 9. (1). Boston, Massachusetts. • McCormick, S.D., L.P. Hansen, T.P. Quinn, and R.L. Saunders. (1998). Movement, migration, and smolting of Atlantic salmon (Salmo salar). Can. J. Fish. Aquat. Sci. 55(S1): 77–92. • National Research Council (NRC). (2002). Genetic status of Atlantic salmon in Maine, Interim Report from the Committee on Atlantic Salmon in Maine. Washington. DC: National Academy Press., 62 pp. • National research Council of the National Academies. (2004). Atlantic Salmon in Maine. Committee on Atlantic Salmon in Maine. Board on Environmental Studies and Toxicology Ocean Studies Board. Division on Earth and Life Studies. The national Academies Press Washington, D.C. • NOAA’s National Marine Fisheries Service (NMFS). (Nov. 2005). Final Recovery Plan for the Gulf of Maine Distinct Population Segment of Atlantic Salmon (Salmo salar). Silver Spring, Maryland and Northeastern Region U.S. Fish and Wildlife Service Hadley, Massachusetts. • Palm, S., and N. Ryman.(1999). Genetic basis of phenotypic differences between transplanted stocks of brown trout. Ecology of Freshwater Fish. 8: 169-180. • Price, B.R. II (2004). Maine Aquaculture, Atlantics Salmon, and Inertia: What is the future for Maine’s net pen salmon industury? Boston College Environmental Affairs Law Review. • Ritter, J.A., G.T. Farmer, R.K. Misra, T.R. Goff, J.K. Bailey, and E.T. Baum. (1986). Parental influences and smolt size and sex ratio effects on sea age at first maturity of Atlantic salmon (Salmo salar). P. 30-38 in D. J. Meerburg, editor. Salmonid age at maturity. Canadian Special Publication of Fisheries and Aquatic Sciences 89, Ottawa. • USASAC (US Atlantic Salmon Assessment Committee). (1999). Annual Report of the US Atlantic Salmon Assessment Committee . 1999/11. USASAC, Gloucester, Massachusetts.

34. Glossary • Imperilment – Exposure to possible harm, loss, or injury. • Smoltification – A metamorphosis that takes place in freshwater juvenile salmon prior to them leaving to saltwater environments. • Anadramous – Fish that breed in fresh water but live their adult life in the sea (salt water). • Iteroparity – Reproduction that occurs repeatedly over the life of the individual. • Distinct Population Segment (DPS) – A subgroup of a vertebrate species that is treated as a species for purposes of listing under the Endangered Species Act. • Atlantic Salmon (AS) – An anadramous fish species found in the Northern Atlantic Ocean and reproducing in freshwater rivers throughout Europe, Iceland, Russia, Canada and the United States. • Substrate – Refers to composition of the ground in a riverbed (for example, silt or gravel). • Spawning – Mating or reproduction in fish. Females release sticky eggs that adhere to the river bed while males release sperm that fertilizes the eggs. • Macroinvertabrates – Small aquatic bug-like creatures. Salmon feed on specifically nymphs of May flies, Caddis and Stones. • Physiological Stress – Internal stress that can include changes in heart rate, metabolism, and internal salt concentrations. Prolonged exposure to this stress without correction by the fish can lead to mortality. • Site Fidelity – The process of returning to the exact place of hatching to spawn. Salmon have a very high site fidelity. In Maine this can be greater than 98 % of the time. • Piscivorous – Fish species that eat other fish. Return To Introduction