Atlantic salmon

The Atlantic salmon (Salmo salar) is a species of ray-finned fish in the family Salmonidae. It is found in the northern Atlantic Ocean, in rivers that flow into the north Atlantic and, due to human introduction, in the north Pacific Ocean.[2][3] Atlantic salmon have long been the target of recreational and commercial fishing, and this, as well as habitat destruction, has reduced their numbers significantly; the species is the subject of conservation efforts in several countries.

Atlantic salmon
Salmo salar
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Salmoniformes
Family: Salmonidae
Genus: Salmo
Species:
S. salar
Binomial name
Salmo salar
Поширення сьомги
Distribution of Atlantic salmon

Nomenclature

The Atlantic salmon was given its scientific binomial name by zoologist and taxonomist Carl Linnaeus in 1758. The name, Salmo salar, derives from the Latin salmo, meaning salmon, and salar, meaning leaper, according to M. Barton,[4] but more likely meaning "resident of salt water". Lewis and Short's Latin Dictionary (Clarendon Press, Oxford, 1879) translates salar as a kind of trout from its use in the Idylls of the poet Ausonius (4th century CE). Later, the differently coloured smolts were found to be the same species.

Other names used to reference Atlantic salmon are: bay salmon, black salmon, caplin-scull salmon, Sebago salmon, silver salmon, fiddler, or outside salmon. At different points in their maturation and life cycle, they are known as parr, smolt, grilse, grilt, kelt, slink, and spring salmon. Atlantic salmon that do not journey to sea are known as landlocked salmon or ouananiche.

Description

Atlantic salmon Atlantic fish
Atlantic salmon are among the largest salmon species

Atlantic salmon are the largest species in their genus, Salmo. After two years at sea, the fish average 71 to 76 cm (28 to 30 in) in length and 3.6 to 5.4 kg (7.9 to 11.9 lb) in weight.[5] But specimens that spend four or more winters feeding at sea can be much larger. An Atlantic salmon netted in 1960 in Scotland, in the estuary of the river Hope, weighed 49.44 kg (109.0 lb), the heaviest recorded in all available literature. Another netted in 1925 in Norway measured 160.65 cm (63.25 in) in length, the longest Atlantic salmon on record.[6]

The colouration of young Atlantic salmon does not resemble the adult stage. While they live in fresh water, they have blue and red spots. At maturity, they take on a silver-blue sheen. The easiest way of identifying them as an adult is by the black spots predominantly above the lateral line, though the caudal fin is usually unspotted. When they reproduce, males take on a slight green or red colouration. The salmon has a fusiform body, and well-developed teeth. All fins, save the adipose, are bordered with black.

Distribution and habitat

Ocean migration of Altantic salmon
Ocean migration of Atlantic salmon[7]

The distribution of Atlantic salmon depends on water temperature. Because of climate change, some of the species' southern populations, in Spain and other warm countries, are growing smaller[8][9] and are expected to be extirpated soon. Before human influence, the natural breeding grounds of Atlantic salmon were rivers in Europe and the eastern coast of North America. When North America was settled by Europeans, eggs were brought on trains to the west coast and introduced into the rivers there. Other attempts to bring Atlantic salmon to new settlements were made; e.g. New Zealand. But since there are no suitable ocean currents on New Zealand, most of these introductions failed. There is at least one landlocked population of Atlantic salmon on New Zealand, where the fish never go out to sea.

Young salmon spend one to four years in their natal river. When they are large enough (c. 15 centimetres (5.9 in)), they smoltify, changing camouflage from stream-adapted with large, gray spots to sea-adapted with shiny sides. They also undergo some endocrinological changes to adapt to osmotic differences between fresh water and seawater habitat. When smoltification is complete, the parr (young fish) now begin to swim with the current instead of against it. With this behavioral change, the fish are now referred to as smolt. When the smolt reach the sea, they follow sea surface currents and feed on plankton or fry from other fish species such as herring. During their time at sea, they can sense the change in the Earth magnetic field through iron in their lateral line.

When they have had a year of good growth, they will move to the sea surface currents that transport them back to their natal river. It is a major misconception that salmon swim thousands of kilometers at sea; instead they surf through sea surface currents. When they reach their natal river they find it by smell; only 5% of Atlantic salmon go up the wrong river. Thus, the habitat of Atlantic salmon is the river where they are born and the sea surface currents that are connected to that river in a circular path.

Wild salmon disappeared from many rivers during the twentieth century due to overfishing and habitat change.[2] By 2000, the numbers of Atlantic salmon had dropped to critically low levels.[10]

Diet

Young salmon begin a feeding response within a few days. After the yolk sac is absorbed by the body, they begin to hunt. Juveniles start with tiny invertebrates, but as they mature, they may occasionally eat small fish. During this time, they hunt both in the substrate and in the current. Some have been known to eat salmon eggs. The most commonly eaten foods include caddisflies, blackflies, mayflies, and stoneflies.[2]

As adults, the salmon prefer capelin as their meal of choice. Capelin are elongated silvery baitfish that grow up to 8-10 inches long.[11]

Behavior

Fry and parr have been said to be territorial, but evidence showing them to guard territories is inconclusive. While they may occasionally be aggressive towards each other, the social hierarchy is still unclear. Many have been found to school, especially when leaving the estuary.

Adult Atlantic salmon are considered much more aggressive than other salmon, and are more likely to attack other fish than others. A matter of concern is where they have become an invasive threat, attacking native salmon, such as Chinook salmon and coho salmon.[2]

Life stages

Life cycle of the Atlantic salmon
Life cycle of the Atlantic salmon

Most Atlantic salmon follow an anadromous fish migration pattern,[3] in that they undergo their greatest feeding and growth in saltwater; however, adults return to spawn in native freshwater streams where the eggs hatch and juveniles grow through several distinct stages.

Atlantic salmon do not require saltwater. Numerous examples of fully freshwater (i.e., "landlocked") populations of the species exist throughout the Northern Hemisphere,[3] including a now extinct population in Lake Ontario, which have been shown in recent studies to have spent their entire life cycle in watershed of the lake.[12] In North America, the landlocked strains are frequently known as ouananiche.

Freshwater phase

The freshwater phases of Atlantic salmon vary between two and eight years, according to river location.[13] While the young in southern rivers, such as those to the English Channel, are only one year old when they leave, those further north, such as in Scottish rivers, can be over four years old, and in Ungava Bay, northern Quebec, smolts as old as eight years have been encountered.[13] The average age correlates to temperature exceeding 7 °C (45 °F).[2]

The first phase is the alevin stage, when the fish stay in the breeding ground and use the remaining nutrients in their yolk sacs. During this developmental stage, their young gills develop and they become active hunters. Next is the fry stage, where the fish grow and subsequently leave the breeding ground in search of food. During this time, they move to areas with higher prey concentration. The final freshwater stage is when they develop into parr, in which they prepare for the trek to the Atlantic Ocean.

During these times, the Atlantic salmon are very susceptible to predation. Nearly 40% are eaten by trout alone. Other predators include other fish and birds.. Egg and juvenile survival is highly dependent on habitat quality as Atlantic salmon are sensitive to ecological change.

Saltwater phases

When parr develop into smolt, they begin the trip to the ocean, which predominantly happens between March and June. Migration allows acclimation to the changing salinity. Once ready, young smolt leave, preferring an ebb tide.

Having left their natal streams, they experience a period of rapid growth during the one to four years they live in the ocean. Typically, Atlantic salmon migrate from their home streams to an area on the continental plate off West Greenland. During this time, they face predation from humans, seals, Greenland sharks, skate, cod, and halibut. Some dolphins have been noticed playing with dead salmon, but it is still unclear whether they consume them.

Once large enough, Atlantic salmon change into the grilse phase, when they become ready to return to the same freshwater tributary they departed from as smolts. After returning to their natal streams, the salmon will cease eating altogether prior to spawning. Although largely unknown, odor – the exact chemical signature of that stream – may play an important role in how salmon return to the area where they hatched. Once heavier than about 250 g, the fish no longer become prey for birds and many fish, although seals do prey upon them. Grey and common seals commonly eat Atlantic salmon. Survivability to this stage has been estimated at between 14 and 53%.[2]

Salmoneggskils

Very young fertilized salmon eggs, notice the developing eyes and neural tube

Salmonlarvakils

Newly hatched alevin feed on their yolk sacs

Atlantic salmon redd

When the alevin or sac fry have depleted their yolk sac or "lunch box", they emerge from the gravel habitat of their redd (nest) to look for food as fry.

Atlantic salmon parr

The fry become parr, and pick home rocks or plants in the streambed from which they dart out to capture insect larvae and other passing food

Salmo salar smolts

When the parr are ready for migration to the ocean, they become smolt

Breeding

The cauld by the Philiphaugh Salmon Viewing Centre - geograph.org.uk - 618657
Fish ladder for Atlantic salmon constructed in the middle of a large weir

Atlantic salmon breed in the rivers of Western Europe from northern Portugal north to Norway, Iceland, and Greenland, and the east coast of North America from Connecticut in the United States north to northern Labrador and Arctic Canada.

The species constructs a nest or "redd" in the gravel bed of a stream. The female creates a powerful downdraught of water with her tail near the gravel to excavate a depression. After she and a male fish have eggs and milt (sperm), respectively, upstream of the depression, the female again uses her tail, this time to shift gravel to cover the eggs and milt which have lodged in the depression.

Unlike the various Pacific salmon species which die after spawning (semelparous), the Atlantic salmon is iteroparous, which means the fish may recondition themselves and return to the sea to repeat the migration and spawning pattern several times, although most spawn only once or twice.[3][14] Migration and spawning exact an enormous physiological toll on individuals, such that repeat spawners are the exception rather than the norm.[14] Atlantic salmon show high diversity in age of maturity and may mature as parr, one- to five-sea-winter fish, and in rare instances, at older sea ages. This variety of ages can occur in the same population, constituting a 'bet hedging' strategy against variation in stream flows. So in a drought year, some fish of a given age will not return to spawn, allowing that generation other, wetter years in which to spawn.[13]

Hybridization

When in shared breeding habitats, Atlantic salmon will hybridize with brown trout (Salmo trutta).[15][16][17] Hybrids between Atlantic salmon and brown trout were detected in two of four watersheds studied in northern Spain. The proportions of hybrids in samples of 'salmon' ranged from 0 to 7-7% but they were not significantly heterogeneous among locations, resulting in a mean hybridization rate of 2-3%. This is the highest rate of natural hybridization so far reported and is significantly greater than rates observed elsewhere in Europe.[18] A recent study discovered extensive hybridization of domesticated Atlantic salmon in the Northwest Atlantic by showing that 27.1% of fish in 17 out of 18 rivers examined are hybrids or feral.[19]

Aquaculture

Færøsk havbrug.1
Atlantic salmon marine cages in the Faroe Islands

In its natal streams, Atlantic salmon are considered prized recreational fish, pursued by fly anglers during its annual runs. At one time, the species supported an important commercial fishery and a supplemental food fishery. However, the wild Atlantic salmon fishery is commercially dead; after extensive habitat damage and overfishing, wild fish make up only 0.5% of the Atlantic salmon available in world fish markets. The rest are farmed, predominantly from aquaculture in Norway, Chile, Canada, the UK, Ireland, Faroe Islands, Russia and Tasmania in Australia. Sport fishing communities, mainly from Iceland and Scandinavia, have joined in the North Atlantic Salmon Fund to buy away commercial quotas in an effort to save the wild species of Salmo salar.[14]

Process

Adult male and female fish are anaesthetised; their eggs and sperm are "stripped" after the fish are cleaned and cloth dried. Sperm and eggs are mixed, washed, and placed into freshwater. Adults recover in flowing, clean, well-aerated water.[20] Some researchers have even studied cryopreservation of their eggs.[21]

Fry are generally reared in large freshwater tanks for 12 to 20 months. Once the fish have reached the smolt phase, they are taken out to sea, where they are held for up to two years. During this time, the fish grow and mature in large cages off the coasts of Canada, the US, or parts of Europe.[14]

Generally, cages are made of two nets. Inner nets, which wrap around the cages, hold the salmon. Outer nets, which are held by floats, keep predators out.[20]

Controversy

Farmed Atlantic salmon are known to occasionally escape from cages and enter the habitat of wild populations. Interbreeding between escaped farm fish and wild fish decreases genetic diversity and introduces "the potential to genetically alter native populations, reduce local adaptation and negatively affect population viability and character."[22]

On the west coast of the United States and Canada, aquaculturists are generally under scrutiny to ensure that non-native Atlantic salmon cannot escape from their open-net pens, however occasional incidents of escape have been documented.[23] During one incident in 2017, for example, up to 300,000 potentially invasive Atlantic salmon escaped a farm among the San Juan Islands in Puget Sound, Washington.[24]

Despite being the source of considerable controversy,[25] the likelihood of escaped Atlantic salmon establishing an invasive presence in the Pacific Northwest is considered minimal, largely because a number of 20th century efforts aimed at deliberately introducing them to the region were ultimately unsuccessful.[26] From 1905 until 1935, for example, in excess of 8.6 million Atlantic salmon of various life stages (predominantly advanced fry) were intentionally introduced to more than 60 individual British Columbia lakes and streams. Historical records indicate, in a few instances, mature sea-run Atlantic salmon were captured in the Cowichan River; however, a self-sustaining population never materialized. Similarly unsuccessful results were realized after deliberate attempts at introduction by Washington as late as the 1980s.[27] Consequently, environmental assessments by the US National Marine Fisheries Service (NMFS), the Washington Department of Fish and Wildlife and the BC Environmental Assessment Office have concluded the potential risk of Atlantic salmon colonization in the Pacific Northwest is low.[28]

Farming of Atlantic Salmon at sea in open cages has been linked to the decline in wild stocks. On exposure to farmed salmon, abundance of all wild migratory salmonid (e.g. Atlantic Salmon, sea trout, pink, chum, and coho Salmon) has been observed to decline; in some case by as much as 50% per generation. It has been shown that this decline can be attributed to both the interbreeding of farmed and wild salmon and the passing of parasites from farmed to wild salmon.[29]

Human impact

Wenceslas Hollar - Salmon fishing (State 1)
Seine fishing for salmon – Wenzel Hollar, 1607–1677

Atlantic salmon were once abundant throughout the North Atlantic. European fishermen gillnetted for Atlantic salmon in rivers using hand-made nets for at least several centuries.[30] Wood and stone weirs along streams and ponds were used for millennia to harvest salmon in the rivers of Maine and New England,[31] and gillnetting was an early fishing technology in colonial America.[32]

Human activities have heavily damaged salmon populations across their range. The major impacts were from overfishing and habitat change, and the new threat from competitive farmed fish. Salmon decline in Lake Ontario goes back to the 18th–19th centuries, due to logging and soil erosion, as well as dam and mill construction. By 1896, the species was declared extirpated from the lake.[33][12] When dams were constructed on the Oswego River, their spawning areas were cut off and they went extinct locally.

In the 1950s, salmon from rivers in the United States and Canada, as well as from Europe, were discovered to gather in the sea around Greenland and the Faroe Islands. A commercial fishing industry was established, taking salmon using drift nets. After an initial series of record annual catches, the numbers crashed; between 1979 and 1990, catches fell from four million to 700,000.[34] Overfishing at sea is generally considered the primary factor.

Pabos Ouest
An Atlantic Salmon Recreational Fishermen in the Pabos River of Quebec.

Beginning around 1990, the rates of Atlantic salmon mortality at sea more than doubled. In the western Atlantic, fewer than 100,000 of the important multiple sea-winter salmon were returning. Rivers of the coast of Maine, southern New Brunswick and much of mainland Nova Scotia saw runs drop precipitously, and even disappear. To find out more about the increased mortality rate, a concerted international effort has been organized by the North Atlantic Salmon Conservation Organization.[35]

Possibly because of improvements in ocean feeding grounds, returns in 2008 were positive. On the Penobscot River in Maine, returns were about 940 in 2007, and by mid-July 2008, the return was 1,938. Similar stories were reported in rivers from Newfoundland to Quebec. In 2011, more than 3,100 salmon returned to the Penobscot, the most since 1986, and nearly 200 ascended the Narraguagus River, up from the low two digits just a decade before.[36]

Recreational fishing of atlantic salmon is now authorized in almost every country with a large atlantic salmon population, but it is subject to many States/Provinces regulations that are designed not to disturb the continuity of the species. Strict catch limits, catch and release practices and forced fly fishing are examples of those regulations.

Recovery

Fishmonger in ICA Fish stall holding a salmon
A fishmonger in Lysekil, Sweden shows a Norwegian salmon.

Around the North Atlantic, efforts to restore salmon to their native habitats are underway, with slow progress. Habitat restoration and protection are key to this process, but issues of excessive harvest and competition with farmed and escaped salmon are also primary considerations. In the Great Lakes, Atlantic salmon have been introduced successfully, but the percentage of salmon reproducing naturally is very low. Most are stocked annually. Atlantic salmon were native to Lake Ontario, but were extirpated by habitat loss and overfishing in the late 19th century. The state of New York has since stocked its adjoining rivers and tributaries, and in many cases does not allow active fishing.[3][37]

Historically, the Housatonic River, and its Naugatuck River tributary, hosted the southernmost Atlantic salmon spawning runs in the United States.[38][39] However, there are historical accounts as early as 1609 from Henry Hudson that Atlantic salmon once ran up the Hudson River.[40]

In the early 1990s, Carlson challenged the notion that Atlantic salmon were prehistorically abundant in New England, when the climate was warmer as it is now. This idea was based on a paucity of bone data in archaeological sites relative to other fish species and claimed that historical observer records were exaggerated.[41][42] However, arguments that lack of archaeological bone fragments rule out historic abundance are more recently disputed because salmon bones are rare at sites that still have large salmon runs, salmonid bones in general are poorly recovered relative to other fish species, and that salmon remains may have been diluted by the large numbers of other anadromous fishes using northeastern streams.[43][44] In addition, fish scale evidence dating to 10,000 years BP places Atlantic salmon in a coastal New Jersey pond.[45]

In New England, many efforts are underway to restore salmon to the region by knocking down obsolete dams and updating others with fish ladders and other techniques that have proven effective in the West with Pacific salmon. There is some success thus far, with populations growing in the Penobscot and Connecticut Rivers. Lake Champlain now has Atlantic salmon. In Ontario, the Atlantic Salmon Restoration Program[46] was started in 2006, and is one of the largest freshwater conservation programs in North America. It has stocked Lake Ontario with over 700,000 young Atlantic salmon. Recent documented successes in the reintroduction of Atlantic salmon include the following:

  • In October 2007, salmon were video-recorded running in Toronto's Humber River by the Old Mill.[33]
  • A migrating salmon was observed in Ontario's Credit River in November 2007.[33]
  • As of 2013, there has been some success in establishing Atlantic salmon in Fish Creek, a tributary of Oneida Lake in central New York.[47]
  • In November 2015, salmon nests were observed in Connecticut in the Farmington River, a tributary of the Connecticut River where Atlantic salmon had not been observed spawning since "probably the Revolutionary War".[48] A 45-year, $25 million federal government effort to restore wild Atlantic salmon to the Connecticut River watershed was discontinued in 2012, but now appears to have been successful.[49]

Atlantic salmon still remains a popular fish for human consumption.[3] It is commonly sold fresh, canned, or frozen.

Beaver impact

The decline in anadromous salmonid species over the last two to three centuries is correlated with the decline in the North American beaver and European beaver, although some fish and game departments continue to advocate removal of beaver dams as potential barriers to spawning runs. Migration of adult Atlantic salmon may be limited by beaver dams during periods of low stream flows, but the presence of juvenile Salmo salar upstream from the dams suggests the dams are penetrated by parr.[50] Downstream migration of Atlantic salmon smolts was similarly unaffected by beaver dams, even in periods of low flows.[50]

In a 2003 study, Atlantic salmon and sea-run brown trout/sea trout spawning in the Numedalslågen River and 51 of its tributaries in southeastern Norway was unhindered by beavers.[51] In a restored, third-order stream in northern Nova Scotia, beaver dams generally posed no barrier to Atlantic salmon migration except in the smallest upstream reaches in years of low flow where pools were not deep enough to enable the fish to leap the dam or without a column of water over-topping the dam for the fish to swim up.[52]

The importance of winter habitat to salmonids afforded by beaver ponds may be especially important in streams of northerly latitudes without deep pools where ice cover makes contact with the bottom of shallow streams.[50] In addition, the up to eight-year-long residence time of juveniles in freshwater may make beaver-created permanent summer pools a crucial success factor for Atlantic salmon populations. In fact, two-year-old Atlantic salmon parr in beaver ponds in eastern Canada showed faster summer growth in length and mass and were in better condition than parr upstream or downstream from the pond.[53]

Legislation

The first laws regarding the Atlantic salmon were started nearly 800 years ago.

England and Wales

Edward I instituted a penalty for collecting salmon during certain times of the year. His son Edward II continued, regulating the construction of weirs. Enforcement was overseen by those appointed by the justices of the peace. Because of confusing laws and the appointed conservators having little power, most laws were barely enforced.

Based on this, a royal commission was appointed in 1860 to thoroughly investigate the Atlantic salmon and the laws governing the species, resulting in the 1861 Salmon Fisheries Act. The act placed enforcement of the laws under the Home Office's control, but it was later transferred to the Board of Trade, and then later to the Board of Agriculture and Fisheries.

Another act passed in 1865 imposed charges to fish and catch limits. It also caused the formation of local boards having jurisdiction over a certain river. The next significant act, passed in 1907, allowed the board to charge 'duties' to catch other freshwater fish, including trout.

Despite legislation, board effects decreased until, in 1948, the River Boards Act gave authority of all freshwater fish and the prevention of pollution to one board per river. In total, it created 32 boards.

In 1974, the 32 boards were reduced to 10 regional water authorities (RWAs). Although only the Northumbrian, Welsh, northwest and southwest RWA's had considerable salmon populations, all ten also cared for trout and freshwater eels.

The Salmon and Freshwater Fisheries Act was passed in 1975. Among other things, it regulated fishing licences, seasons, and size limits, and banned obstructing the salmon's migratory paths.[2]

Scotland

Salmon was greatly valued in medieval Scotland, and various fishing methods, including the use of weirs, cruives, and nets, were used to catch the fish. Fishing for salmon was heavily regulated in order to conserve the resource.[54] In 1318, King Robert I enacted legislation setting a minimum size for cruives, "so that no fry of fish are impeded from ascending and descending..." Laws on catching fish upon royal lands were frequently updated, demonstrating their importance.[54] Because the fish were held in such high regard, poachers were severely punished; a person twice convicted of poaching salmon on a royal estate could be sentenced to death.[55] The export of salmon was economically important in Aberdeen; beginning in the 15th century, the fish could be preserved through salting and barreling, allowing it to be exported abroad, including as far away as the Baltic. The volume of the early Scottish salmon trade is impossible to determine, since surviving custom records date only from the 1420 onward, and since Aberdeen burgesses enjoyed an exemption on salmon customs until the 1530s.[56]

During the 15th century, many laws were passed; many regulated fishing times, and worked to ensure smolts could safely pass downstream. James III even closed a meal mill because of its history of killing fish attracted to the wheel.

More recent legislation has established commissioners who manage districts. Furthermore, the Salmon and Freshwater Fisheries Act in 1951 required the Secretary of State be given data about the catches of salmon and trout to help establish catch limits.[2][20]

United States

Several populations of Atlantic salmon are in serious decline, and are listed as endangered under the Endangered Species Act (ESA). Currently, runs of 11 rivers in Maine are on the list – Kennebec, Androscoggin, Penobscot, Sheepscot, Ducktrap, Cove Brook, Pleasant, Narraguagus, Machias, East Machias and Dennys. The Penobscot River is the "anchor river" for Atlantic salmon populations in the US. Returns in 2008 have been around 2,000, more than double the 2007 return of 940.

Section 9 of the ESA makes it illegal to take an endangered species of fish or wildlife. The definition of "take" is to "harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to attempt to engage in any such conduct".[57]

Canada

The federal government has prime responsibility for protecting the Atlantic salmon, but over the last generation, effort has continued to shift management as much as possible to provincial authorities through memoranda of understanding, for example. A new Atlantic salmon policy is in the works, and in the past three years, the government has attempted to pass a new version of the century-old Fisheries Act through Parliament.

Federal legislation regarding at-risk populations is weak. Inner Bay of Fundy Atlantic salmon runs were declared endangered in 2000. As of 2008, no recovery plan is in place.

It takes constant pressure from nongovernmental organizations, such as the Atlantic Salmon Federation, for improvements in management, and for initiatives to be considered. For example, the technology for mitigation of acid rain-affected rivers used in Norway is needed in 54 Nova Scotia rivers. Yet, an initiative of the ASF and the Nova Scotia Salmon Association raised the funds to get a project in place, in West River-Sheet Harbour.

In Quebec, the daily catch limit for Atlantic salmon is one fish over 63 cm (25 in), two fish under 63 cm (25 in) or one fish over and one under 63 cm (25 in), provided 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.

In Lake Ontario, the historic populations of Atlantic salmon became extinct, and cross-national efforts have been under way to reintroduce the species, with some areas already having restocked naturally reproducing populations.[58][59]

NASCO

The North Atlantic Salmon Conservation Organization is an international council made up of Canada, the European Union, Iceland, Norway, the Russian Federation, and the United States, with its headquarters in Edinburgh.[60] It was established in 1983 to help protect Atlantic salmon stocks, through the cooperation between nations. They work to restore habitat and promote conservation of the salmon.

Sustainable consumption

In 2010, Greenpeace International has added the Atlantic salmon to its seafood red list. "The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries".[61]

See also

Notes

  1. ^ Baillie, J.; Groombridge, B. (1996). "Salmo salar". IUCN Red List of Threatened Species. 1996: e.T14144A4408913. doi:10.2305/iucn.uk.1996.rlts.t19855a9026693.en. Retrieved 26 August 2016.
  2. ^ a b c d e f g h Shearer, W. (1992). The Atlantic Salmon. Halstead Press.
  3. ^ a b c d e f The Audubon Society Field Guide to North American Fishes, Whales & Dolphins. Chanticleer Press. 1983. p. 395.
  4. ^ Barton, M.: "Biology of Fishes.", pages 198–202 Thompson Brooks/Cole 2007
  5. ^ "Atlantic salmon (Salmo salar)". NOAA Fisheries - Office of Protected Resources. 2017-05-05.
  6. ^ "Buller F., The Domesday Book of Giant Salmon Volume 1 & 2. Constable (2007) & Constable (2010)
  7. ^ "Atlantic Salmon Life Cycle". Connecticut River Coordinator's Office. U.S. Fish and Wildlife Service. 13 September 2010. Archived from the original on 15 January 2014.
  8. ^ "Same number of fishermen, but less salmon in Spanish rivers". science daily. August 26, 2011. Retrieved April 30, 2016.
  9. ^ J. L. Horreo; G. Machado-Schiaffino; A. M. Griffiths; D. Bright; J. R. Stevens; E. Garcia-Vazquez. (2011). "Atlantic Salmon at Risk: Apparent Rapid Declines in Effective Population Size in Southern European Populations". Transactions of the American Fisheries Society. 140 (3): 605–610. doi:10.1080/00028487.2011.585574.
  10. ^ B. Dempson; C. J. Schwarz; D. G. Reddin; M. F. O'Connell; C. C. Mullins; C. E. Bourgeois (2001). "Estimation of marine exploitation rates on Atlantic salmon (Salmo salar L.) stocks in Newfoundland, Canada" (PDF). ICES Journal of Marine Science. 58: 331–341. doi:10.1006/jmsc.2000.1014. Retrieved 7 May 2011.
  11. ^ Fisheries, NOAA (2018-08-21). "Atlantic Salmon - Protected | NOAA Fisheries". www.fisheries.noaa.gov. Retrieved 2018-11-26.
  12. ^ a b "Study sheds light on extinct Lake Ontario salmon". Toronto Star, November 9, 2016, page GT1.
  13. ^ a b c Klemetsen A, Amundsen P-A, Dempson JB, Jonsson B, Jonsson N, O'Connell MF, Mortensen E (2003). "Atlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.): a review of aspects of their life histories". Ecology of Freshwater Fish. 12: 1–59. doi:10.1034/j.1600-0633.2003.00010.x.
  14. ^ a b c d Heen, K. (1993). Salmon Aquaculture. Halstead Press.
  15. ^ Youngson, A. F., Webb, J. H., Thompson, C. E., and Knox, D. 1993. Spawning of escaped farmed Atlantic salmon (Salmo salar): hybridization of females with brown trout (Salmo trutta). Canadian Journal of Fisheries and Aquatic Sciences, 50:1986-1990.
  16. ^ Matthews, M. A., Poole, W. R., Thompson, C. E., McKillen, J., Ferguson, A., Hindar, K., and Wheelan, K. F. 2000. Incidence of hybridization between Atlantic salmon, Salmo salar L., and brown trout, Salmo trutta L., in Ireland. Fisheries Management and Ecology, 7:337-347.
  17. ^ Seawater tolerance in Atlantic salmon, Salmo salar L., brown trout, Salmo trutta L., and S. salar × S. trutta hybrids smolt. Urke HA, Koksvik J, Arnekleiv JV, Hindar K, Kroglund F, Kristensen T. Source Norwegian Institute of Water Research, 7462, Trondheim, Norway. henning.urke(@)niva.no
  18. ^ Natural hybridization between Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in northern Spain by Carlos Garcia de Leaniz
  19. ^ Wringe, Brenden; et al. (2018). "Extensive hybridization following a large escape of domesticated Atlantic salmon in the Northwest Atlantic". Communications Biology. 1: 108. doi:10.1038/s42003-018-0112-9. PMC 6123692. PMID 30271988.
  20. ^ a b c Sedgwick, S. (1988). Salmon Farming Handbook. Fishing News Books LTD.
  21. ^ N. Bromage (1995). Broodstock Management and Egg and Larval Quality. Blackwell Science.
  22. ^ Thorstad, Eva B.; Fleming, Ian A.; McGinnity, Philip; Soto, Doris; Wennevik, Vidar; Whoriskey, Fred (2008). Incidence and impacts of escaped farmed Atlantic salmon Salmo salar in nature (PDF). World Wildlife Fund, Inc. p. 6. ISBN 978-82-426-1966-2. Retrieved 25 August 2017.
  23. ^ Barry, Tricia K.; VanderZwaag, David L. (2007). Preventing Salmon Escapes from Aquaculture in Canada and the USA: Limited International Coordinates, Divergent Regulatory Currents and Possible Future Courses (PDF). Oxford, UK: Blackwell Publishing Ltd. p. 58. Retrieved 25 August 2017.
  24. ^ Donaldson, Jim (August 22, 2017). "Fish farm fiasco: Why officials want you to catch as many salmon as you can". Bellingham Herald. Retrieved 23 August 2017.
  25. ^ Mapes, Linda V.; Bernton, Hal (August 22, 2017). "Please go fishing, Washington state says after farmed Atlantic salmon escape broken net". The Seattle Times. Retrieved 27 December 2017.
  26. ^ Amos, Kevin H.; Appleby, Andrew. "Atlantic Salmon in Washington State: A Fish Management Perspective" (PDF). Washington Department of Fish & Wildlife. State of Washington. Retrieved 27 December 2017.
  27. ^ Pechlaner, Gabriela; Rutherford, Murray B. (Summer 2006). "Common Future, Different Policy Paths? Managing the Escape of Farmed Atlantic Salmon in British Columbia and Washington State". BC Studies (150): 47. Retrieved 25 August 2017.
  28. ^ R. M. J. Ginetz (May 2002). "On the Risk of Colonization by Atlantic Salmon in BC waters" (PDF). B.C. Salmon Farmers Association.
  29. ^ Ford, Jennifer S.; Myers, Ransom A. (12 February 2008). "A Global Assessment of Salmon Aquaculture Impacts on Wild Salmonids". PLOS Biology. 6 (2): e33. doi:10.1371/journal.pbio.0060033. ISSN 1545-7885. PMC 2235905. PMID 18271629.
  30. ^ Jenkins, J. Geraint (1974). Nets and Coracles, p. 68. London, David and Charles.
  31. ^ "The River". The Penobscot River Restoration Trust. 2013-09-25. Retrieved 19 November 2013.
  32. ^ Netboy, Anthony (1973) The Salmon: Their Fight for Survival, pp. 181-182. Boston, Houghton Mifflin.
  33. ^ a b c Harb, M. "Upstream Battle", Canadian Geographic Magazine, June 2008, p. 24
  34. ^ "Salmon campaigner lands top award". BBC News. 22 April 2007.
  35. ^ "Atlantic Salmon". animallist.weebly.com. Retrieved 19 November 2013.
  36. ^ Carpenter, Murray (26 December 2011). "Shiny Patches in Maine's Streambeds Are Bright Sign for Salmon". The New York Times. Retrieved 11 February 2012.
  37. ^ Mills, D. (1989). Ecology and Management of Atlantic Salmon. Springer-Verlag.
  38. ^ Fay, C.; M. Bartron; S. Craig; A. Hecht; J. Pruden; R. Saunders; T. Sheehan; J. Trial (2006). Status Review for Anadromous Atlantic Salmon (Salmo salar) in the United States. Report to the National Marine Fisheries Service and U.S. Fish and Wildlife Service (Report). p. 294. Retrieved July 3, 2016.
  39. ^ Kendall, W. C. (1935). The fishes of New England: the salmon family. Part 2 - the salmons. Boston, Massachusetts: Memoirs of the Boston Society of Natural History: monographs on the natural history of New England. p. 90. Retrieved July 3, 2016.
  40. ^ W.C. Kendall (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. 9 (1): 1–166. Retrieved July 3, 2016.
  41. ^ Catherine C. Carlson (1988). GP Nicholas, ed. Where's the salmon? A reevaluation of the role of anadromous fisheries in aboriginal New England in Holocene human ecology in Northeastern North America. New York: Plenum Press. ISBN 978-0306428692.
  42. ^ Catherine C. Carlson (1996). "The [In]Significance of Atlantic Salmon". History Through a Pinhole. 8(3/4 (Fall/Winter). Retrieved July 3, 2016.
  43. ^ Stephen F. Jane; Keith H. Nislow; Andrew R. Whiteley (September 2014). "The use (and misuse) of archaeological salmon data to infer historical abundance in North America with a focus on New England". Reviews in Fish Biology and Fisheries. 24 (3): 943–954. doi:10.1007/s11160-013-9337-3.
  44. ^ Brian S. Robinson; George L. Jacobson; Martin G. Yates; Arthur E. Spiess; Ellen R. Cowie (October 2009). "Atlantic salmon, archaeology and climate change in New England". Journal of Archaeological Science. 36 (10): 2184–2191. doi:10.1016/j.jas.2009.06.001. Retrieved July 3, 2016.
  45. ^ Robert A. Daniels; Doroty Peteet (November 1998). "Fish scale evidence for rapid post-glacial colonization of an Atlantic coastal pond". Global Ecology & Biogeography Letters. 7 (6): 467–476. doi:10.2307/2997716. hdl:2060/19990023267. JSTOR 2997716. Retrieved July 3, 2016.
  46. ^ "Lake Ontario Atlantic Salmon Restoration Program".
  47. ^ Figura, David. "Cicero angler lands 27-inch Atlantic salmon in Oneida Lake". Syracuse.com. Syracuse Media Group. Retrieved 4 February 2016.
  48. ^ Hladky, Gregory B. (25 Dec 2015). "Salmon Found Spawning In Farmington River Watershed For First Time in Centuries". Hartford Courant. Tribune Company. Retrieved 4 February 2016.
  49. ^ Jaymi Heimbuch (March 11, 2016). "Wild Atlantic salmon are spawning in Connecticut River for the first time in 200 years". Mother Nature Network. Retrieved July 3, 2016.
  50. ^ a b c P. Collen & R. J. Gibson (2001). "The general ecology of beavers (Castor spp.), as related to their influence on stream ecosystems and riparian habitats, and the subsequent effects on fish – a review" (PDF). Reviews in Fish Biology and Fisheries. 10 (4): 439–461. doi:10.1023/A:1012262217012.
  51. ^ Howard Park & Øystein Cock Rønning (2007). "Low potential for restraint of anadromous salmonid reproduction by beaver Castor fiber in the Numedalslågen river catchment, Norway". River Research and Applications. 23 (7): 752–762. doi:10.1002/rra.1008.
  52. ^ Barry A. Taylor; Charles MacInnis; Trevor A. Floyd (2010). "Influence of Rainfall and Beaver Dams on Upstream Movement of Spawning Atlantic Salmon in a Restored Brook in Nova Scotia, Canada". River Research and Applications: 183–193. doi:10.1002/rra.1252.
  53. ^ Douglas B. Sigourney, Benjamin H. Letcher & Richard A. Cunjak (2006). "Influence of beaver activity on summer growth and condition of age-2 Atlantic salmon parr". Transactions of the American Fisheries Society. 135 (4): 1068–1075. doi:10.1577/T05-159.1.
  54. ^ a b Kate Buchanan, "Wheeles and Creels: The Physical Representation of the Right to Milling and Fishing in Sixteenth-Century Angus, Scotland" in Medieval and Early Modern Representations of Authority in Scotland and the British Isles (eds. Kate Buchanan & Lucinda H.S. Dean with Michael Penman: Routledge, 2016), pp. 59-60.
  55. ^ Jim Mac Laughlin,Troubled Waters: A Social and Cultural History of Ireland's Sea Fisheries (Four Courts Press, 2010), p. 77.
  56. ^ Katie Stevenson, Power and Propaganda: Scotland, 1306-1488 (Edinburgh University Press, 2014).
  57. ^ (16 U.S.C. 1532(19)) http://www.epa.gov/EPA-SPECIES/1998/May/Day-01/e11668.htm
  58. ^ "Frequently Asked Questions (FAQ)". Bring Back the Salmon Lake Ontario. Retrieved 17 September 2015.
  59. ^ "Endangered Populations". Atlantic Salmon Federation. Retrieved 17 September 2015.
  60. ^ "NASCO ~ The North Atlantic Salmon Conservation Organization". Nasco.int. Archived from the original on 21 January 2013. Retrieved 11 February 2012.
  61. ^ "Greenpeace International Seafood Red list". Greenpeace International. Archived from the original on 10 April 2010.

References

External links

Amoebic gill disease

Amoebic gill disease (AGD) is a potentially fatal disease of some marine fish. It is caused by Neoparamoeba perurans, the most important amoeba in cultured fish. It primarily affects farm raised fish of the Salmonidae family, most notably affecting the Tasmanian Atlantic Salmon (Salmo salar) industry, costing the A$20 million a year in treatments and lost productivity. Turbot, bass, bream, sea urchins and crabs have also been infected.

The disease has also been reported affecting the commercial salmon fisheries of the United States, Australia, New Zealand, France, Spain, Ireland and Chile. It was first diagnosed in the summer of 1984/1985 in populations of Atlantic Salmon off the east coast of Tasmania and was found to be caused by the Neoparamoeba perurans n.sp.

AquAdvantage salmon

AquAdvantage salmon is a genetically modified (GM) Atlantic salmon developed by AquaBounty Technologies in 1989. A growth hormone-regulating gene from Pacific Chinook salmon, with a promoter gene from ocean pout, were added to the Atlantic salmon's genes (Tillmann, 2016, Bondar 2010). These two genes enable the GM salmon to grow year-round instead of only during spring and summer. The stability of the new DNA construct was tested. It revealed no additional mutational effects during insertion other than the two desired genes. (Bondar 2010) These GM fish were back-crossed (a two generation breeding protocol that starts by generating a hybrid offspring between two inbred strains, one of them carrying the mutation of interest) to wild-type Atlantic salmon, and the genetically modified EO-1ɑ gene sequence was identical in the second through fourth generations, indicating that the insertion is stable. (Bondar 2010).

GM salmon are a commercially competitive alternative to wild-caught salmon and to fish farming of unmodified salmon. The purpose of the modifications is to increase the speed at which the fish grows without affecting its ultimate size or other qualities. GM fish grows to market size in 16 to 18 months rather than three years. The latter figure refers to fish-farmed Atlantic salmon whose growth rates had already been improved over wild fish as a result of traditional selective breeding practices.

Aquaculture of salmonids

The aquaculture of salmonids is the farming and harvesting of salmonids under controlled conditions for both commercial and recreational purposes. Salmonids (particularly salmon and rainbow trout), along with carp, and tilapia are the three most important fish species in aquaculture. The most commonly commercially farmed salmonid is the Atlantic salmon. In the U.S. Chinook salmon and rainbow trout are the most commonly farmed salmonids for recreational and subsistence fishing through the National Fish Hatchery System. In Europe, brown trout are the most commonly reared fish for recreational restocking. Commonly farmed nonsalmonid fish groups include tilapia, catfish, sea bass, and bream.

In 2007, the aquaculture of salmonids was worth US$10.7 billion globally. Salmonid aquaculture production grew over ten-fold during the 25 years from 1982 to 2007. In 2012, the leading producers of salmonids were Norway, Chile, Scotland and Canada.Much controversy exists about the ecological and health impacts of intensive salmonids aquaculture. Of particular concern are the impacts on wild salmon and other marine life. Some of this controversy is part of a major commercial competitive fight for market share and price between Alaska commercial salmonid fishermen and the rapidly evolving salmonid aquaculture industry.

Atlantic Salmon Federation

The Atlantic Salmon Federation (ASF) is an international conservation organization established in 1948.The Federation is dedicated to the conservation, protection and restoration of wild Atlantic salmon and the ecosystems on which their well being and survival depend.

ASF's headquarters are in St. Andrews, New Brunswick, Canada, with regional offices in each of the Atlantic provinces, Quebec, and Maine.

ASF has a network of seven regional councils (New Brunswick, Nova Scotia, Newfoundland and Labrador, Prince Edward Island, Quebec, Maine and Western New England), which cover the freshwater range of wild Atlantic salmon in Canada and the United States.

Campbellton, New Brunswick

Campbellton is a city with a population of 6,883 (2016) in Restigouche County, New Brunswick, Canada.Situated on the south bank of the Restigouche River opposite Pointe-à-la-Croix, Quebec, Campbellton was officially incorporated in 1889 and achieved city status in 1958.

Forestry and tourism are major industries in the regional economy, while a pulp mill in nearby Atholville is the largest single employer in the area. As part of the tourism "industry", wealthy sportfishermen seeking Atlantic salmon flock to the scenic Restigouche Valley every summer. The region sees extensive annual snowfall. Alpine and Nordic ski facilities at Sugarloaf Provincial Park provide winter recreation opportunities for both visitors and local residents.

Campbellton is also a retail and service centre for Restigouche County.

Fish counter

Automatic fish counters are automatic devices for measuring the number of fish passing along a particular river in a particular period of time. Usually one particular species is of interest.

One important species studied by fish counters are Atlantic salmon. This species is of interest owing to its ecologically vulnerable status and anadromous lifestyles.

Gyrodactylus salaris

Gyrodactylus salaris, commonly known as salmon fluke, is a tiny monogenean ectoparasite which lives on the body surface of freshwater fish. This leech-like parasite has been implicated in the reduction of Atlantic salmon populations in the Norwegian fjords. It also parasitises other species, including rainbow trout. G. salaris requires fresh water, but can survive in brackish water for up to 18 hours.The parasite is 0.5 mm (0.02 in) long, and cannot be seen with the naked eye, but it can be seen with a magnifying glass. On its posterior end is a haptor, a specialized organ for attaching to the host fish, which has sixteen hooks around its edge. The parasite is viviparous, that is, it produces live offspring.

The parasites give birth to live young nearly as big as themselves and at this time, a further generation is already growing inside the neonates.

Hammond River (New Brunswick)

The Hammond River is a tributary of the Kennebecasis River in New Brunswick, Canada.

The Hammond River runs approximately 40 kilometres in southern Kings County along the border of Saint John County.

One of southern New Brunswick's best Atlantic salmon rivers, the Hammond River rises in the Caledonia Highlands near the rural community of Hammondvale and runs in a westerly direction through a scenic river valley framed by high hills, passing through small farming communities to its junction with the Kennebecasis River.

Near the mouth of the Hammond River, several kilometres northeast of Quispamsis at the rural community of Nauwigewauk, the river is joined by a short tributary draining Darlings Lake. In the broad Kennebecasis River Valley, the Hammond River's flow rate is substantially reduced and it meanders through a large wetland before joining the Kennebecasis River flowage.

The Hammond River and Darlings Lake form the south and west water bodies surrounding Darlings Island, with the Kennebecasis River and the Hampton Marsh forming the north and easterly water bodies.

The Hammond River Angling association was formed to help protect the river, as it is one of the few rivers in the world that still has spawning Atlantic salmon.

Margaree River

The Margaree River (Abhainn Mhargaraidh) is a river on Cape Breton Island in Nova Scotia. The northeast branch of the river derives from the watershed of the Cape Breton Highlands, while the Southwest Margaree flows northeast from Lake Ainslie. The two branches join at Margaree Forks. The river then flows north to empty into the Gulf of Saint Lawrence at Margaree Harbour, Nova Scotia. The river is 120 km in length and drains an area of 1,375 km². The Margaree has been well known for a century for its trout and Atlantic salmon sport fishery, that draws anglers from near and far. Fishing is highly regulated now and is restricted to fly fishing only, with barbless hooks, in the main stem of the river. Famed American angler and Atlantic salmon conservationist Lee Wulff caught his first salmon on a fly on the Margaree in 1933.The gravel bars of the upper Northeast Margaree provide spawning grounds for Atlantic salmon; its steep valleys provide habitat for American marten and the rare Gaspé shrew. The Margaree Valley includes a mix of farms and woodlands.

During the 18th century, Acadians settled along the coast near the mouth of the river; the French name for this river was St. Marguerite. Scottish Highlanders began to settle in the Margaree Valley at the beginning of the 19th century.

Moses Coady, a noted son of the Margaree Valley, attended school in Margaree Forks and later, taught there before completing his education in Antigonish and Rome.The Margaree was designated a Canadian Heritage River in 1998.

HMCS Margaree, a World War II Canadian naval destroyer, was named after this river.

North Atlantic Salmon Conservation Organization

The North Atlantic Salmon Conservation Organization (NASCO) is an international organization established under the Convention for the Conservation of Salmon in the North Atlantic Ocean from 1 October 1983.

The organization's mission is to contribute through consultation and cooperation to the conservation, restoration, enhancement and rational management of salmon stocks.

Its headquarters are in Edinburgh, United Kingdom.

River Bush

The River Bush (from the Irish: an Bhuais) is a river in County Antrim, Northern Ireland. The River Bush is 33.5 miles (53.9 km) long. The river's source is in the Antrim Hills at 480m. From there the river flows northwest, with a bend at the town of Armoy. It then flows west, passing through Stranocum, and then bends north, passing through Bushmills before reaching the sea at Portballintrae on the North Antrim coast. It flows through a fertile valley devoted to grassland-based agriculture with limited arable cropping. The underlying geology is basalt and the water is slightly alkaline with magnesium making an unusually large contribution to total hardness. The river supports indigenous stocks of Atlantic salmon and brown trout. Saint Columb's Rill, which is a tributary of the river, is the source of water used for distilling Bushmills whiskey.

Salmo

Salmo is a genus of fish in the salmon family Salmonidae that includes the European species of salmon and trout, among them the familiar Atlantic salmon Salmo salar and the brown trout Salmo trutta. The natural distribution of Salmo also extends to Northern Africa and to Western Asia around the Black Sea basin. The single Salmo species naturally found in the Atlantic North America is the Atlantic salmon, whereas the salmon and trout of the Pacific basin belong to another genus, Oncorhynchus. The generic name Salmo derives from the Latin salmō (salmon). The number of distinct species and subspecies in Salmo is a debated issue. Atlantic salmon and brown trout are widespread species, while most of the other taxa are narrowly distributed forms endemic to single watersheds.

Salmon

Salmon is the common name for several species of ray-finned fish in the family Salmonidae. Other fish in the same family include trout, char, grayling and whitefish. Salmon are native to tributaries of the North Atlantic (genus Salmo) and Pacific Ocean (genus Oncorhynchus). Many species of salmon have been introduced into non-native environments such as the Great Lakes of North America and Patagonia in South America. Salmon are intensively farmed in many parts of the world.

Typically, salmon are anadromous: they hatch in fresh water, migrate to the ocean, then return to fresh water to reproduce. However, populations of several species are restricted to fresh water through their lives. Folklore has it that the fish return to the exact spot where they hatched to spawn. Tracking studies have shown this to be mostly true. A portion of a returning salmon run may stray and spawn in different freshwater systems; the percent of straying depends on the species of salmon. Homing behavior has been shown to depend on olfactory memory. Salmon date back to the Neogene.

Salmon isavirus

Infectious salmon anemia (ISA) is a viral disease of Atlantic salmon (Salmo salar) caused by Salmon isavirus. It affects fish farms in Canada, Norway, Scotland and Chile, causing severe losses to infected farms. ISA has been a World Organisation for Animal Health notifiable disease since 1990. In the EU, it is classified as a non-exotic disease, and is monitored by the European Community Reference Laboratory for Fish Diseases.

Salmon run

The salmon run is the time when salmon, which have migrated from the ocean, swim to the upper reaches of rivers where they spawn on gravel beds. After spawning, all Pacific salmon and most Atlantic salmon die, and the salmon life cycle starts over again. The annual run can be a major event for grizzly bears, bald eagles and sport fishermen. Most salmon species migrate during the fall (September through November).Salmon spend their early life in rivers, and then swim out to sea where they live their adult lives and gain most of their body mass. When they have matured, they return to the rivers to spawn. Usually they return with uncanny precision to the natal river where they were born, and even to the very spawning ground of their birth. It is thought that, when they are in the ocean, they use magnetoception to locate the general position of their natal river, and once close to the river, that they use their sense of smell to home in on the river entrance and even their natal spawning ground.

In northwest America, salmon is a keystone species, which means the impact they have on other life is greater than would be expected in relation to their biomass. The death of the salmon has important consequences, since it means significant nutrients in their carcasses, rich in nitrogen, sulfur, carbon and phosphorus, are transferred from the ocean to terrestrial wildlife such as bears and riparian woodlands adjacent to the rivers. This has knock-on effects not only for the next generation of salmon, but to every species living in the riparian zones the salmon reach. The nutrients can also be washed downstream into estuaries where they accumulate and provide much support for estuarine breeding birds.

Salmonidae

Salmonidae is a family of ray-finned fish, the only living family currently placed in the order Salmoniformes. It includes salmon, trout, chars, freshwater whitefishes, and graylings, which collectively are known as the salmonids. The Atlantic salmon and trout of the genus Salmo give the family and order their names.

Salmonids have a relatively primitive appearance among the teleost fish, with the pelvic fins being placed far back, and an adipose fin towards the rear of the back. They are slender fish, with rounded scales and forked tails. Their mouths contain a single row of sharp teeth. Although the smallest species is just 13 cm (5.1 in) long as an adult, most are much larger, with the largest reaching 2 m (6.6 ft).All salmonids spawn in fresh water, but in many cases, the fish spend most of their lives at sea, returning to the rivers only to reproduce. This lifecycle is described as anadromous. They are predators, feeding on small crustaceans, aquatic insects, and smaller fish.

Sea louse

A sea louse (plural sea lice), not to be confused with sea fleas, is a member of a family of copepods (small crustaceans) within the order Siphonostomatoida, family Caligidae. There are roughly 559 species in 37 genera include around 162 Lepeophtheirus and 268 Caligus species. Sea lice are marine ectoparasites (external parasites) that feed on the mucus, epidermal tissue, and blood of host marine fish.

The genera Lepeophtheirus and Caligus parasitize marine fish, in particular those species that have been recorded on farmed salmon. Lepeophtheirus salmonis and various Caligus species are adapted to salt water and are major ectoparasites of farmed and wild Atlantic salmon. Several antiparasitic drugs have been developed for control purposes. L. salmonis is the best understood in the areas of its biology and interactions with its salmon host.

Caligus rogercresseyi has become a major parasite of concern on salmon farms in Chile, and studies are under way to gain a better understanding of the parasite and the host-parasite interactions. Recent evidence is also emerging that L. salmonis in the Atlantic has sufficient genetic differences from L. salmonis from the Pacific to suggest that Atlantic and Pacific L. salmonis may have independently co-evolved with Atlantic and Pacific salmonids, respectively.

Shepards River

The Shepards River is a 13.6-mile-long (21.9 km) river in western Maine and eastern New Hampshire in the United States. It is part of the Saco River drainage basin.

The Shepards River rises in the town of Eaton, New Hampshire, among foothills of the White Mountains. The river flows northeast into Brownfield, Maine, passing the villages of West Brownfield, Brownfield, and East Brownfield before reaching the Saco River east of Frost Mountain.

Several species of game fish have been caught in Shepards River, including brook trout, rainbow trout, largemouth bass, and atlantic salmon.

Teleost leptins

Teleost leptins are a family of peptide hormones found in fish (teleostei) that are orthologs of the mammalian hormone leptin. The teleost and mammalian leptins appear to have similar functions, namely, regulation of energy intake and expenditure.

The leptin (LEP) hormone was long thought to be specific to mammals, but in recent years the gene (lep) has been found in amphibia such as the tiger salamander (Ambystoma tigrinum), and the African clawed frog (Xenopus laevi). The discovery of lep in puffer fish (Takifugu rubripes) demonstrates the ancient ancestry of this hormone.

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