A Little More About Atlantic Salmon

  • By Mike McKimm. From the BBC.

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    My thoughts:

    It is sometimes thought that Atlantic salmon (Salmo salar) are somehow the bad guy since we only seem to hear about them in connection with fish farming. The truth is that Atlantic salmon are an ancient, wild and vibrant species native to the Atlantic Ocean and in 2009 the NOAA Fisheries Service and the U.S. Fish and Wildlife Service (USFWS) listed most populations as “endangered.”

    The irresponsible fishing practices of old and other factors resulted in the precipetous decline of the Atlantic salmon. While that the (Convention for Conservation of Salmon in the North Atlantic, T.I.A.S. 10789)* protects wild populations from further commercial exploitation, fish farming is rendering that treaty steril.

    *This Convention was signed in Reykjavik, Iceland, on March 2, 1982, and entered into force, October 1, 1983. The parties (United States, Canada, Denmark, European Community, Iceland, Norway) established an international organization for the conservation and protection of Atlantic salmon.

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    Here is some more information on Atlantic salmon from NOAA:

    Atlantic Salmon (Wild) (Salmo salar )

    • Wild Atlantic salmon population levels are very low, and commercial fishing for the species is prohibited. Almost all of the Atlantic salmon sold in the United States comes from aquaculture operations.
    • Atlantic salmon aquaculture in the United States meets high environmental and health standards and is involved in improving best practices for aquaculture worldwide.
    • Salmon is an excellent source of protein and omega-3 fatty acids. For more information on nutrition, please see Nutrition Facts. (USDA)
    • Atlantic salmon is currently produced domestically in aquaculture operations in Maine and Washington State. The United States also imports farmed salmon, mainly from Norway, Chile, and Canada.

    Sustainability Status

    Biomass: Atlantic salmon stocks are currently at perilously low levels.
    Overfishing:
    No – commercial fisheries are prohibited.
    Overfished: Yes – commercial and recreational fisheries were permitted for much of the 20th century and contributed to the historic decline of Atlantic salmon.
    Fishing and habitat: There is currently no directed or incidental commercial fishery for Atlantic salmon in federal waters.
    Bycatch: There is currently no directed or incidental commercial fishery for Atlantic salmon in federal waters.
    Aquaculture: With the decline of wild Atlantic salmon populations in the early 1800s, fish culture efforts have sustained an important Atlantic salmon fishery resource in New England. Since the first state fish commission was established in New Hampshire in 1864, salmon have been regulated and cultured in an effort to preserve this valuable fisheries resource. Commercial aquaculture ventures started in the late 1970s with the first experimental harvest of Atlantic salmon in 1979 of 6 metric tons (13,227 pounds). Since then, the mariculture industry in eastern North America has grown to produce more than 32,000 metric tons (70.5 million pounds) annually since 1997. In Maine, production increased rapidly and peaked at about 16,500 metric tons (36.5 million pounds) in 2000, but abruptly declined to below 6,000 metric tons (13.2 million pounds) in 2005.

    Science and Management

    Atlantic salmon is managed by the Northeast Fishery Management Council through the Fishery Management Plan for Atlantic Salmon, originally implemented March 17, 1988. The FMP established U.S. management authority over all Atlantic salmon of U.S. origin. The FMP currently prohibits possession of Atlantic salmon and any directed or incidental (bycatch) commercial fishery for Atlantic salmon in federal waters. Effectively, this protects the entire U.S. population complex in U.S. marine waters and is complementary to management practiced by the states in riverine and coastal waters. However, distant water fisheries must be managed as well to conserve and restore U.S. salmon populations.

    The United States joined with other North Atlantic nations in 1982 to form the North Atlantic Salmon Conservation Organization (NASCO) for the purpose of managing salmon through a cooperative program of conservation, restoration, and enhancement of North Atlantic stocks. The United States’ interest in NASCO stemmed from its desire to ensure that interception fisheries of U.S. origin fish were not susceptible to mixed stock fisheries in West Greenland and St. Pierre et Miquelon and did not compromise the long term commitment by the states and federal government to rehabilitate and restore New England Atlantic salmon stocks. The International Council for the Exploration of the Sea (ICES) is the official research arm of NASCO and is responsible for providing scientific advice to be used by NASCO members as a basis for formulating biologically sound management recommendations for the conservation of North Atlantic salmon stocks.

    In 2000, NOAA Fisheries Service and the U.S. Fish and Wildlife Service (USFWS) listed the Gulf of Maine (GOM) Distinct Population Segment (DPS) of Atlantic salmon as endangered under the Endangered Species Act. A DPS is a subgroup of a vertebrate species that is treated as a species for purposes of listing under the Endangered Species Act. The USFWS and NOAA Fisheries Service have joint responsibility for recovery of the endangered GOM DPS of Atlantic salmon. In December 2005, the USFWS and NOAA Fisheries Service, in coordination with the State of Maine, finalized the Recovery Plan for the GOM DPS of Atlantic salmon. The Recovery Plan identifies recovery actions needed to halt the decline of the species and lays out a process to minimize threats. In June 2009, NOAA Fisheries Service and USFWS extended Endangered Species Act protection to more Atlantic salmon by adding fish in the Penobscot, Kennebec, and Androscoggin rivers and their tributaries to the endangered GOM DPS. It also applies wherever these fish occur in these rivers’ estuaries and marine environment. Hatchery fish used to supplement these natural populations are also including in this ruling.

    Life History and Habitat

    Life history, including information on the habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed.

    • Geographic range: There are three generally recognized groups of Atlantic salmon: North American, European, and Baltic. The North American group, including the Canadian and U.S. populations, historically ranged from northern Quebec southeast to Newfoundland and southwest to Long Island Sound. Most adults from these three populations migrate to feeding areas off the west coast of Greenland.
    • Habitat: Adult Atlantic salmon spend their entire adult life in open ocean habitat migrating along the coast of North America to Greenland to find suitable forage. Juvenile Atlantic salmon hatch in the spring and spend the first two years of life in fresh water rivers and streams. These young of the year fish, or parr, spend the first year of life in habitat that is typically characterized by “riffle” areas (shallow water depth and moderate to fast water flow with adequate cover). This habitat is often called nursery habitat. Parr are very territorial and move into habitat with larger substrate as they grow; typically these areas tend to be faster flowing with deeper water depths than nursery areas.
    • Life span: 4 to 10 years
    • Food: Juvenile Atlantic salmon mostly prey upon invertebrates and terrestrial insects while in freshwater and amphipods (small, shrimp-like crustaceans), euphausiids (krill), gammarids, and fishes while at sea. Larger adult Atlantic salmon mainly prey on fish such as Atlantic herring, alewife, rainbow smelt, capelin, mummichogs, sand lances, flatfish, and small Atlantic mackerel.
    • Growth rate: Growth rates are variable, depending on a combination of season, habitat quality, age, sex, and population density. Marine growth is much faster than freshwater growth, allowing adult salmon to reach lengths averaging 28 to 30 inches and weights averaging 8 to 12 pounds after two years at sea.
    • Maximum size: A salmon that has spawned multiple times can weigh as much as 30 pounds, although fish of that size are uncommon.
    • Reaches reproductive maturity: Most U.S. salmon return home to spawn after their second winter at sea; they are known as 2 Sea Winter (2SW) fish. A small portion (about 10%) of U.S. salmon, typically males, become sexually mature and return to natal rivers to spawn after one winter at sea (1 SW) and are often referred to as Grilse.
    • Reproduction: Adult Atlantic salmon return to natal rivers each spring and throughout the fall to spawn in cold headwater streams. Females will lay an average of 7,500 eggs, of which only about 9-20 % will survive to the fry stage. Fry remain buried in the gravel for about 6 weeks. Eggs incubate slowly due to cold winter water temperatures. The fry emerge from the gravel about mid-May. Emergent fry quickly disperse from nests (called redds) within the gravel. They develop camouflaging stripes along their sides and enter the parr stage. Salmon parr spend 2-3 years in freshwater (after which they are about 6 inches long) and then undergo a physiological transformation called smoltification that prepares them for life in a marine habitat. During smoltification, fish imprint on the chemical nature of the stream or river to enable them to find their way back to where they were born. In the spring, after smoltfication is complete, smolts migrate to the ocean.
    • Spawning season: Fall
    • Spawning grounds: Atlantic salmon spawn in freshwater. Suitable spawning habitat consists of cold water with gravel or rubble substrate, typically toward the tails of pools or in areas of moving water.
    • Migrations: New England stocks travel vast distances across the open ocean to return to spawning grounds in rivers and streams. Tagging data for New England stocks indicate that U.S. salmon migrate as far north as Greenland.
    • Predators: Predators of Atlantic salmon include birds, marine mammals, native and non-native fish species, and humans.
    • Commercial or recreational interest: Both
    • Distinguishing characteristics: Atlantic salmon have a spindle-like body shape – rounded, broad in the middle, and tapered at each end. The shape is somewhat flattened toward the sides, which is typical of salmonids in general. The head is relatively small, about one-fifth of the body length. Ventral (underside) paired fins are prominent, especially on juveniles.

    Role in the Ecosystem

    U.S. salmon have developed heritable adaptations to local riverine ecosystem factors such as climate, soil type, and hydrology. These factors are particularly important because they influence ecosystem structure and function including transfer of energy in aquatic food chains. Also, U.S. salmon are one component of a larger co-evolved diadromous fish complex that historically inhabited most rivers in New England. This complex historically contained such fish as alewife (Alosa pseudoharengus), blueback herring (Alosa aestivalis) and American shad (Alosa sapidissima) and has been severely depleted or completely removed from many rivers.

    Biomass

    Biomass refers to the amount of Atlantic salmon in the ocean. Biomass estimates are not available for Atlantic salmon. Unlike most fish stocks, biomass metrics are not used to describe the status of salmon stocks. U.S. Atlantic salmon populations are assessed by the U.S. Atlantic Salmon Assessment Committee, a team of state and federal biologists who collect data on the species throughout New England and report population status. Population status of salmon can be determined by counting adults returning to spawn either directly at traps and weirs or indirectly using redd (nest) surveys and a recently developed redd regression model. Because most U.S. salmon are products of stocking, it is important to consider those inputs in stock assessments as well.

    Atlantic salmon stocks began a steady decline in the early 1900s due to overfishing and habitat destruction. They remain at extremely low levels today. Restoration projects developed throughout the latter half of the 20th century focused on revitalizing salmon stocks throughout New England, and successfully utilized hatchery production as a tool for enhancing salmon runs.

    Landings

    Atlantic salmon landings **click to enlarge**Landings refer to the amount of catch that is brought to land. Because no reporting requirements were established for the fishery, landings data are incomplete. In 1989, all state and federal commercial salmon fisheries in New England were closed by law. In 2006 and 2007, a catch and release recreational fishery for Atlantic salmon in the Penobscot River was authorized by the State of Maine.

    Note: Only domestic commercial landings are shown in the graph.

    Biomass and Landings

    Biomass and landings data can sometimes be used to detect trends in a fishery. They may influence each other, and factors such as changes in management measures, fishing effort, market preferences, or environmental conditions may impact landings and biomass as well.

    Data sources:
    Landings from NOAA Fisheries Service Annual Commercial Landings Statistics using “SALMON, ATLANTIC” as Species and “ALL STATES” as State

    Important Dates

    1988 – New England Fishery Management Council’s Atlantic Salmon FMP implemented
    1999 – NOAA Fisheries Service and U.S. Fish and Wildlife Service (USFWS) complete status review of the species
    2000 – NOAA Fisheries Service and USFWS publish final rule listing the Gulf of Maine DPS as an endangered species
    2002 – NOAA Fisheries Service completes Biological Opinion for aquaculture activities
    2005 – NOAA Fisheries Service and USFWS complete the Final Recovery Plan for the Gulf of Maine DPS of Atlantic salmon
    2006 – NOAA Fisheries Service and USFWS complete a revised status review of the species
    2009 – NOAA Fisheries Service and USFWS expand Gulf of Maine DPS and determine critical habitat (the area needed to support the fish population’s survival and recovery) for the endangered Atlantic salmon


    January 12th, 2012 | Traveler | No Comments |

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