112-515: The Atlantic salmon ( Salmo salar ) is a species of ray-finned fish in the family Salmonidae . It is the third largest of the Salmonidae, behind Siberian taimen and Pacific Chinook salmon , growing up to a meter in length. Atlantic salmon are found in the northern Atlantic Ocean and in rivers that flow into it. Most populations are anadromous , hatching in streams and rivers but moving out to sea as they grow where they mature, after which
224-423: A mutation–selection balance . It is predicted that a viral quasispecies at a low but evolutionarily neutral and highly connected (that is, flat) region in the fitness landscape will outcompete a quasispecies located at a higher but narrower fitness peak in which the surrounding mutants are unfit, "the quasispecies effect" or the "survival of the flattest". There is no suggestion that a viral quasispecies resembles
336-515: A taxonomic rank of an organism, as well as a unit of biodiversity . Other ways of defining species include their karyotype , DNA sequence, morphology , behaviour, or ecological niche . In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. About 14% of these had been described by 2011. All species (except viruses ) are given
448-542: A two-part name , called a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature , also sometimes in zoological nomenclature ). For example, Boa constrictor is one of the species of the genus Boa , with constrictor being the species' epithet. While the definitions given above may seem adequate at first glance, when looked at more closely they represent problematic species concepts. For example,
560-400: A "classical" method of determining species, such as with Linnaeus, early in evolutionary theory. However, different phenotypes are not necessarily different species (e.g. a four-winged Drosophila born to a two-winged mother is not a different species). Species named in this manner are called morphospecies . In the 1970s, Robert R. Sokal , Theodore J. Crovello and Peter Sneath proposed
672-424: A 'smallest clade' idea" (a phylogenetic species concept). Mishler and Wilkins and others concur with this approach, even though this would raise difficulties in biological nomenclature. Wilkins cited the ichthyologist Charles Tate Regan 's early 20th century remark that "a species is whatever a suitably qualified biologist chooses to call a species". Wilkins noted that the philosopher Philip Kitcher called this
784-604: A common species with a conservation status of " least concern ", however it has been 25 years since the IUCN has released this status. A more recent regional assessment revealed that the European population of this species is vulnerable, and this might be the same or a similar status globally. Location-specific assessments have shown population declines across parts of the Atlantic Salmon's natural range, with populations along
896-428: A connected series of neighbouring populations, each of which can sexually interbreed with adjacent related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each "linked" population. Such non-breeding, though genetically connected, "end" populations may co-exist in the same region thus closing
1008-432: A different species from its ancestors. Viruses have enormous populations, are doubtfully living since they consist of little more than a string of DNA or RNA in a protein coat, and mutate rapidly. All of these factors make conventional species concepts largely inapplicable. A viral quasispecies is a group of genotypes related by similar mutations, competing within a highly mutagenic environment, and hence governed by
1120-630: A farm among the San Juan Islands in Puget Sound, Washington. Washington went on in 2019 to implement a gradual phase out of salmon farming to be completed by 2025. Despite being the source of considerable controversy, 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
1232-508: A genetic boundary suitable for defining a species concept is present. DNA barcoding has been proposed as a way to distinguish species suitable even for non-specialists to use. One of the barcodes is a region of mitochondrial DNA within the gene for cytochrome c oxidase . A database, Barcode of Life Data System , contains DNA barcode sequences from over 190,000 species. However, scientists such as Rob DeSalle have expressed concern that classical taxonomy and DNA barcoding, which they consider
SECTION 10
#17327721393151344-454: A higher price than some other fish. It has thus long been the target of recreational and commercial fishing , and this, as well as habitat destruction , has impacted the population in some areas. As a result, the species is the subject of conservation efforts in several countries, which appear to have been somewhat successful since the 2000s. Techniques to farm this species using aquacultural methods have also been developed, and at present it
1456-778: 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 for the Atlantic salmon are: bay salmon, black salmon, caplin-scull salmon, fiddler, sebago salmon, silver salmon, outside salmon and winnish. 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 [ fr ] in North America). Atlantic salmon are
1568-465: A lineage should be divided into multiple chronospecies , or when populations have diverged to have enough distinct character states to be described as cladistic species. Species and higher taxa were seen from the time of Aristotle until the 18th century as categories that could be arranged in a hierarchy, the great chain of being . In the 19th century, biologists grasped that species could evolve given sufficient time. Charles Darwin 's 1859 book On
1680-682: 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. 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
1792-492: A misnomer, need to be reconciled, as they delimit species differently. Genetic introgression mediated by endosymbionts and other vectors can further make barcodes ineffective in the identification of species. A phylogenetic or cladistic species is "the smallest aggregation of populations (sexual) or lineages (asexual) diagnosable by a unique combination of character states in comparable individuals (semaphoronts)". The empirical basis – observed character states – provides
1904-449: A particular species, including which genus (and higher taxa) it is placed in, is a hypothesis about the evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be corroborated or refuted. Sometimes, especially in the past when communication was more difficult, taxonomists working in isolation have given two distinct names to individual organisms later identified as
2016-505: A paucity of bone data in archaeological sites relative to other fish species, and the assertion that historical claims of abundance may have been exaggerated. This argument was later challenged in another paper which claimed that lack of archaeological bone fragments could be explained by salmon bones being rare at sites that still have large salmon runs and that salmonid bones in general are poorly recovered relative to other fish species. Atlantic salmon populations were significantly reduced in
2128-400: A perfect model of life, it is still a useful tool to scientists and conservationists for studying life on Earth, regardless of the theoretical difficulties. If species were fixed and clearly distinct from one another, there would be no problem, but evolutionary processes cause species to change. This obliges taxonomists to decide, for example, when enough change has occurred to declare that
2240-400: A short way of saying that something applies to many species within a genus, but not to all. If scientists mean that something applies to all species within a genus, they use the genus name without the specific name or epithet. The names of genera and species are usually printed in italics . However, abbreviations such as "sp." should not be italicised. When a species' identity is not clear,
2352-401: A slight green or red colouration. The salmon has a fusiform body, and well-developed teeth . All fins, except the adipose fin , are bordered with black. The natural breeding grounds of Atlantic salmon are rivers in Europe and the northeastern coast of North America. In Europe, Atlantic salmon are still found as far south as Spain, and as far north as Russia. Because of sport-fishing, some of
SECTION 20
#17327721393152464-404: A specialist may use "cf." before the epithet to indicate that confirmation is required. The abbreviations "nr." (near) or "aff." (affine) may be used when the identity is unclear but when the species appears to be similar to the species mentioned after. With the rise of online databases, codes have been devised to provide identifiers for species that are already defined, including: The naming of
2576-523: A species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups. It has been argued that this definition is a natural consequence of the effect of sexual reproduction on the dynamics of natural selection. Mayr's use of the adjective "potentially" has been a point of debate; some interpretations exclude unusual or artificial matings that occur only in captivity, or that involve animals capable of mating but that do not normally do so in
2688-400: A species as determined by a taxonomist. A typological species is a group of organisms in which individuals conform to certain fixed properties (a type), so that even pre-literate people often recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens (such as longer or shorter tails) would differentiate the species. This method was used as
2800-491: A species. All species definitions assume that an organism acquires its genes from one or two parents very like the "daughter" organism, but that is not what happens in HGT. There is strong evidence of HGT between very dissimilar groups of prokaryotes , and at least occasionally between dissimilar groups of eukaryotes , including some crustaceans and echinoderms . The evolutionary biologist James Mallet concludes that there
2912-685: A species. Generally the term includes the unknown element of a distinct act of creation. Many authors have argued that a simple textbook definition, following Mayr's concept, works well for most multi-celled organisms , but breaks down in several situations: Species identification is made difficult by discordance between molecular and morphological investigations; these can be categorised as two types: (i) one morphology, multiple lineages (e.g. morphological convergence , cryptic species ) and (ii) one lineage, multiple morphologies (e.g. phenotypic plasticity , multiple life-cycle stages). In addition, horizontal gene transfer (HGT) makes it difficult to define
3024-528: A taxonomic decision at the discretion of cognizant specialists, is not governed by the Codes of Zoological or Botanical Nomenclature, in contrast to the PhyloCode , and contrary to what is done in several other fields, in which the definitions of technical terms, like geochronological units and geopolitical entities, are explicitly delimited. The nomenclatural codes that guide the naming of species, including
3136-517: A traditional biological species. The International Committee on Taxonomy of Viruses has since 1962 developed a universal taxonomic scheme for viruses; this has stabilised viral taxonomy. Most modern textbooks make use of Ernst Mayr 's 1942 definition, known as the Biological Species Concept as a basis for further discussion on the definition of species. It is also called a reproductive or isolation concept. This defines
3248-447: A variation on the morphological species concept, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms. It differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species
3360-515: A variety of reasons. Viruses are a special case, driven by a balance of mutation and selection , and can be treated as quasispecies . Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics . Early taxonomists such as Linnaeus had no option but to describe what they saw: this was later formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts,
3472-427: 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 kilometres at sea; instead they surf through sea surface currents. It is possible they find their natal river by smell, although this is not confirmed; only 5% of Atlantic salmon go up the wrong river. The range of an individual Atlantic salmon can thus be
Atlantic salmon - Misplaced Pages Continue
3584-438: Is "an entity composed of organisms which maintains its identity from other such entities through time and over space, and which has its own independent evolutionary fate and historical tendencies". This differs from the biological species concept in embodying persistence over time. Wiley and Mayden stated that they see the evolutionary species concept as "identical" to Willi Hennig 's species-as-lineages concept, and asserted that
3696-529: Is a 1609 account by Henry Hudson that Atlantic salmon once ran up the Hudson River . In addition, fish scale evidence dating to 10,000 years BP places Atlantic salmon in a coastal New Jersey pond. Two publications from 1988 and 1996 questioned the notion that Atlantic salmon were prehistorically plentiful in New England, when the climate was warmer as it is now. This argument was primarily based on
3808-400: Is a group of sexually reproducing organisms that recognise one another as potential mates. Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms; no matter whether populations can hybridise successfully, they are still distinct cohesion species if
3920-458: Is a set of organisms adapted to a particular set of resources, called a niche, in the environment. According to this concept, populations form the discrete phenetic clusters that we recognise as species because the ecological and evolutionary processes controlling how resources are divided up tend to produce those clusters. A genetic species as defined by Robert Baker and Robert Bradley is a set of genetically isolated interbreeding populations. This
4032-414: Is called speciation . Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book The Origin of Species . Speciation depends on a measure of reproductive isolation , a reduced gene flow. This occurs most easily in allopatric speciation, where populations are separated geographically and can diverge gradually as mutations accumulate. Reproductive isolation
4144-463: Is commonly sold fresh, canned, or frozen. Wood and stone weirs along streams and ponds were used for millennia to harvest salmon in the rivers of New England. European fishermen gillnetted for Atlantic salmon in rivers using hand-made nets for many centuries and gillnetting was also used in early colonial America. In its natal streams, Atlantic salmon are considered prized recreational fish, pursued by fly anglers during its annual runs. At one time,
4256-481: 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
4368-403: Is described formally, in a publication that assigns it a unique scientific name. The description typically provides means for identifying the new species, which may not be based solely on morphology (see cryptic species ), differentiating it from other previously described and related or confusable species and provides a validly published name (in botany) or an available name (in zoology) when
4480-696: Is farmed in great numbers in many places around the world. Although this is now a viable alternative to wild-caught fish, farming methods have attracted criticism from environmentalists. The Atlantic salmon was given its scientific binomial name by Swedish 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, but more likely meaning "resident of salt water" . Lewis and Short's Latin Dictionary (Clarendon Press, Oxford, 1879) translates salar as
4592-671: Is further weakened by the existence of microspecies , groups of organisms, including many plants, with very little genetic variability, usually forming species aggregates . For example, the dandelion Taraxacum officinale and the blackberry Rubus fruticosus are aggregates with many microspecies—perhaps 400 in the case of the blackberry and over 200 in the dandelion, complicated by hybridisation , apomixis and polyploidy , making gene flow between populations difficult to determine, and their taxonomy debatable. Species complexes occur in insects such as Heliconius butterflies, vertebrates such as Hypsiboas treefrogs, and fungi such as
Atlantic salmon - Misplaced Pages Continue
4704-726: Is hard or even impossible to test. Later biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, and the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: (1) agamospecies for asexual organisms (2) biospecies for reproductively isolated sexual organisms (3) ecospecies based on ecological niches (4) evolutionary species based on lineage (5) genetic species based on gene pool (6) morphospecies based on form or phenotype and (7) taxonomic species,
4816-528: 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. Most Atlantic salmon follow an anadromous migration pattern, in that they undergo their greatest feeding and growth in saltwater; however, adults return to spawn in native freshwater streams where
4928-403: Is no easy way to tell whether related geographic or temporal forms belong to the same or different species. Species gaps can be verified only locally and at a point of time. One is forced to admit that Darwin's insight is correct: any local reality or integrity of species is greatly reduced over large geographic ranges and time periods. The botanist Brent Mishler argued that the species concept
5040-478: Is not valid, notably because gene flux decreases gradually rather than in discrete steps, which hampers objective delimitation of species. Indeed, complex and unstable patterns of gene flux have been observed in cichlid teleosts of the East African Great Lakes . Wilkins argued that "if we were being true to evolution and the consequent phylogenetic approach to taxa, we should replace it with
5152-586: Is similar to Mayr's Biological Species Concept, but stresses genetic rather than reproductive isolation. In the 21st century, a genetic species could be established by comparing DNA sequences. Earlier, other methods were available, such as comparing karyotypes (sets of chromosomes ) and allozymes ( enzyme variants). An evolutionarily significant unit (ESU) or "wildlife species" is a population of organisms considered distinct for purposes of conservation. In palaeontology , with only comparative anatomy (morphology) and histology from fossils as evidence,
5264-654: Is sometimes an important source of genetic variation. Viruses can transfer genes between species. Bacteria can exchange plasmids with bacteria of other species, including some apparently distantly related ones in different phylogenetic domains , making analysis of their relationships difficult, and weakening the concept of a bacterial species. fusiform Spindle-like shape [REDACTED] Spindle with yarn [REDACTED] A lemon in geometry [REDACTED] Look up fusiform or fusiformis in Wiktionary,
5376-437: 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
5488-412: 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
5600-594: Is threatened by hybridisation, but this can be selected against once a pair of populations have incompatible alleles of the same gene, as described in the Bateson–Dobzhansky–Muller model . A different mechanism, phyletic speciation, involves one lineage gradually changing over time into a new and distinct form (a chronospecies ), without increasing the number of resultant species. Horizontal gene transfer between organisms of different species, either through hybridisation , antigenic shift , or reassortment ,
5712-477: 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 dependent on habitat quality as Atlantic salmon are sensitive to ecological change. When parr develop into smolt , they begin
SECTION 50
#17327721393155824-530: The ICZN for animals and the ICN for plants, do not make rules for defining the boundaries of the species. Research can change the boundaries, also known as circumscription, based on new evidence. Species may then need to be distinguished by the boundary definitions used, and in such cases the names may be qualified with sensu stricto ("in the narrow sense") to denote usage in the exact meaning given by an author such as
5936-710: The extirpation of early-run fish in many watersheds. The inshore Atlantic salmon fishery became a major export of the New World, with major fishing operations establishing along the shores of major river systems. The southernmost populations were the first to disappear. 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
6048-399: The fly agaric . Natural hybridisation presents a challenge to the concept of a reproductively isolated species, as fertile hybrids permit gene flow between two populations. For example, the carrion crow Corvus corone and the hooded crow Corvus cornix appear and are classified as separate species, yet they can hybridise where their geographical ranges overlap. A ring species is
6160-507: The jaguar ( Panthera onca ) of Latin America or the leopard ( Panthera pardus ) of Africa and Asia. In contrast, the scientific names of species are chosen to be unique and universal (except for some inter-code homonyms ); they are in two parts used together : the genus as in Puma , and the specific epithet as in concolor . A species is given a taxonomic name when a type specimen
6272-695: The substrate and in the current. Some have been known to eat salmon eggs. Plankton such as euphausiids are important food for pre-grilse but amphipods and decapods are also consumed. The most commonly eaten foods include caddisflies , blackflies , mayflies , stoneflies , and chironomids , as well as terrestrial insects. As adults, the salmon prefer capelin as their meal of choice. Capelin are elongated silvery fish that grow up to 20–25 centimetres (8–10 in) long. Other fish consumed include herring , alewives , smelts , scomberids , sand lance , and small cod . Fry and parr have been said to be territorial, but evidence showing them to guard territories
6384-406: The "cynical species concept", and arguing that far from being cynical, it usefully leads to an empirical taxonomy for any given group, based on taxonomists' experience. Other biologists have gone further and argued that we should abandon species entirely, and refer to the "Least Inclusive Taxonomic Units" (LITUs), a view that would be coherent with current evolutionary theory. The species concept
6496-657: The 1980s. 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. A study of Næve et al. (2022) estimated the impact of 50 years of genetic selection and tried to predict
6608-668: The North Atlantic Salmon Fund to buy commercial quotas in the Atlantic from commercial fishermen in an effort to preserve wild Salmo salar stocks. Possibly because of improvements in ocean feeding grounds, returns in 2008 were very 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
6720-782: The Northwest Atlantic, showing that 27.1% of fish in 17 out of 18 rivers examined are artificially stocked or hybrids. Farming of Atlantic salmon in open cages at sea has also been linked, at least in part, to a decline in wild stocks attributed to the passing of parasites from farmed to wild individuals. 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. During one incident in 2017 , for example, up to 300,000 potentially invasive Atlantic salmon escaped
6832-496: The Norwegian salmon aquaculture production between 2016 and 2019 was used as a base case. The simulation of the expected growth until 2050 (generation 24) gave five different scenarios : Historical (H1), Forecast 1 (F1), Forecast 2 (F2), Forecast 3 (F3) and Forecast 4 (F4). Changes in thermal growth coefficient (TGC) per generation were used in the model to simulate the differences in the five scenarios. The genetic data, H1, and
SECTION 60
#17327721393156944-626: The Origin of Species explained how species could arise by natural selection . That understanding was greatly extended in the 20th century through genetics and population ecology . Genetic variability arises from mutations and recombination , while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures . Genes can sometimes be exchanged between species by horizontal gene transfer ; new species can arise rapidly through hybridisation and polyploidy ; and species may become extinct for
7056-532: The Penobscot, the most since 1986, and nearly 200 ascended the Narraguagus River , up from the low two digits just a decade before. Species A species ( pl. : species) is a population of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring , typically by sexual reproduction . It is the basic unit of classification and
7168-434: The United States following European settlement. The fur trade, timber harvesting, dams and mills and agriculture degraded freshwater habitats and lowered the carrying capacity of most North American streams. Beaver populations were trapped to near-extinction by 1800, and log drives and clear-cutting further exacerbated stream erosion and habitat loss. As timber and fur gave way to agriculture, freshwater Atlantic salmon habitat
7280-405: The abbreviation "sp." in the singular or "spp." (standing for species pluralis , Latin for "multiple species") in the plural in place of the specific name or epithet (e.g. Canis sp.). This commonly occurs when authors are confident that some individuals belong to a particular genus but are not sure to which exact species they belong, as is common in paleontology . Authors may also use "spp." as
7392-453: The adults seasonally move upstream again to spawn. When the mature fish re-enter rivers to spawn, they change in colour and appearance. Some populations of this fish only migrate to large lakes, and are "landlocked", spending their entire lives in freshwater. Such populations are found throughout the range of the species. Unlike Pacific species of salmon, S. salar is iteroparous , which means it can survive spawning and return to sea to repeat
7504-570: The amount of hybridisation is insufficient to completely mix their respective gene pools . A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology , genes can move freely even between distantly related bacteria, possibly extending to the whole bacterial domain. As a rule of thumb, microbiologists have assumed that members of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA–DNA hybridisation to decide if they belong to
7616-412: 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%. Atlantic salmon breed in the rivers of Western Europe from northern Portugal north to Norway , Iceland , and Greenland , and
7728-474: The biological species concept, "the several versions" of the phylogenetic species concept, and the idea that species are of the same kind as higher taxa are not suitable for biodiversity studies (with the intention of estimating the number of species accurately). They further suggested that the concept works for both asexual and sexually-reproducing species. A version of the concept is Kevin de Queiroz 's "General Lineage Concept of Species". An ecological species
7840-505: The biological species concept, a cladistic species does not rely on reproductive isolation – its criteria are independent of processes that are integral in other concepts. Therefore, it applies to asexual lineages. However, it does not always provide clear cut and intuitively satisfying boundaries between taxa, and may require multiple sources of evidence, such as more than one polymorphic locus, to give plausible results. An evolutionary species, suggested by George Gaylord Simpson in 1951,
7952-428: The boundaries between closely related species become unclear with hybridisation , in a species complex of hundreds of similar microspecies , and in a ring species . Also, among organisms that reproduce only asexually , the concept of a reproductive species breaks down, and each clone is potentially a microspecies. Although none of these are entirely satisfactory definitions, and while the concept of species may not be
8064-708: The coast of Maine and the Inner Bay of Fundy now listed as " endangered " under the Endangered Species Act, and the Canadian Species at Risk Act, respectively. Human activities have impacted salmon populations across parts of its range. The major threats are from overfishing and habitat change. 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,
8176-433: The concept of a chronospecies can be applied. During anagenesis (evolution, not necessarily involving branching), some palaeontologists seek to identify a sequence of species, each one derived from the phyletically extinct one before through continuous, slow and more or less uniform change. In such a time sequence, some palaeontologists assess how much change is required for a morphologically distinct form to be considered
8288-464: 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
8400-512: The effect in the industry when the full genetic potential is utilized. This assumes a further development of advanced techniques in the years to come. The authors of the article found that the daily yield of the biomass increased with increasing generations in the historic and forecast scenarios. Further, the production time in seawater to reach the harvest weight of 5100 g is expected to be reduced by 53% in 2050. When production time can be reduced, this will also reduce e.g. time at risk of diseases. In
8512-454: 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. Migration and spawning exact an enormous physiological toll on individuals, such that repeat spawners are
8624-487: 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 , including a now extinct population in Lake Ontario , which has been shown in recent studies to have spent its entire life cycle in the watershed of the lake. In North America,
8736-435: The evidence to support hypotheses about evolutionarily divergent lineages that have maintained their hereditary integrity through time and space. Molecular markers may be used to determine diagnostic genetic differences in the nuclear or mitochondrial DNA of various species. For example, in a study done on fungi , studying the nucleotide characters using cladistic species produced the most accurate results in recognising
8848-831: The exception rather than the norm. 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. When in shared breeding habitats, Atlantic salmon will hybridize with brown trout ( Salmo trutta ). 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 these proportions were not significantly homogeneous among locations, resulting in
8960-428: 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. Some researchers have even studied cryopreservation of their eggs. 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,
9072-714: The fish grow and mature in large cages off the coasts of Canada, the US, or parts of Europe. There are many different commercially available cage designs built to operate in a wide variety of aquatic conditions. High-density polyethylene (HDPE) cages are widely used, with HDPE pipes forming a floating collar ring onto which the fish net pen is secured and suspended in the water below. Advancements in cage technologies have allowed for reduction in fish escapes, improvement in growing conditions, and maximization of aquaculture production volume per unit area of growing space. Farmed Atlantic salmon are known to occasionally escape from cages and enter
9184-454: The free dictionary. Fusiform (from Latin fusus ‘spindle’) means having a spindle -like shape that is wide in the middle and tapers at both ends. It is similar to the lemon-shape , but often implies a focal broadening of a structure that continues from one or both ends, such as an aneurysm on a blood vessel . Examples [ edit ] Fusiform, a body shape common to many aquatic animals , characterized by being tapered at both
9296-631: 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". A study in 2000 demonstrated that the genes of farmed Atlantic salmon intrude wild populations mainly through wild males breeding with farmed females, though farmed specimens showed reduced capacity for breeding success overall compared to their wild counterparts. Further study in 2018 discovered extensive cross-breeding of wild and farmed Atlantic salmon in
9408-541: The head and the tail Fusiform, a classification of aneurysm Fusiform bacteria (spindled rods, that is, fusiform bacilli), such as the Fusobacteriota Fusiform cell (biology) Fusiform face area , a part of the human visual system which seems to specialize in facial recognition Fusiform gyrus , part of the temporal lobe of the brain Fusiform muscle , where the fibres run parallel along
9520-429: The impact it could have until 2050. In order to do this, a common garden experiment was used to model and simulate past and future effects for 11 generations of genetic selection of increased growth rate in Atlantic salmon. To model the contribution that breeding has made in the industry from generation 0 (harvested in 1975– 1978) to generation 11 (harvested in 2017 – 2019), and to simulate growth until 2050 (generation 24),
9632-645: The landlocked strains are frequently known as ouananiche . The freshwater phases of Atlantic salmon vary between two and eight years, according to river location. 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. The first phase
9744-632: 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. 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,
9856-417: The length of the muscle Fusiform neuron, a spindle-shaped neuron References [ edit ] ^ Ulanski, S.L. (2003). The Science of Fly-fishing . University of Virginia Press. p. 93. ISBN 978-0-8139-2210-2 . Retrieved 13 July 2021 . See also [ edit ] Streamliner , a fusiform hydro-/aero-dynamic vehicle. Historically, the adjective "streamlined"
9968-416: The longest Atlantic salmon on record. 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
10080-639: The most conservative forecast scenario, F1, simulate what can be expected in 2050 if the trend from generation 0 through 11 is maintained. The following forecast scenarios assume a greater increase in genetic growth with a larger increase in the TGC in the generations to come. In the next two generations, more advanced selection methods such as marker assisted selection (from generation 10) and genomic selection (from generation 11) were implemented. This resulted in increased gain in selection for growth and simulated F2 and F3. The most progressive scenario, F4, aimed at exploring
10192-457: The most progressive scenario, mortality in seawater was expected to be reduced by up to 50%. Further, the authors found that production per license can increase by up to 121%. Additionally, 77% of the new volume needed to achieve five million tonnes in 2050, may be provided by genomic selection. However, one should keep in mind that this article was published by the firm Aquagen, and can possibly be biased and too optimistic. The IUCN rates this as
10304-483: The numerous fungi species of all the concepts studied. Versions of the phylogenetic species concept that emphasise monophyly or diagnosability may lead to splitting of existing species, for example in Bovidae , by recognising old subspecies as species, despite the fact that there are no reproductive barriers, and populations may intergrade morphologically. Others have called this approach taxonomic inflation , diluting
10416-593: The paper is accepted for publication. The type material is usually held in a permanent repository, often the research collection of a major museum or university, that allows independent verification and the means to compare specimens. Describers of new species are asked to choose names that, in the words of the International Code of Zoological Nomenclature , are "appropriate, compact, euphonious, memorable, and do not cause offence". Books and articles sometimes intentionally do not identify species fully, using
10528-674: The person who named the species, while the antonym sensu lato ("in the broad sense") denotes a wider usage, for instance including other subspecies. Other abbreviations such as "auct." ("author"), and qualifiers such as "non" ("not") may be used to further clarify the sense in which the specified authors delineated or described the species. Species are subject to change, whether by evolving into new species, exchanging genes with other species, merging with other species or by becoming extinct. The evolutionary process by which biological populations of sexually-reproducing organisms evolve to become distinct or reproductively isolated as species
10640-594: The presence of juvenile salmon upstream of the dams suggests they are penetrated by parr . Downstream migration of Atlantic salmon smolts was similarly unaffected by beaver dams, even in periods of low flows. In a 2003 study, Atlantic salmon and sea-run brown trout spawning in the Numedalslågen River and 51 of its tributaries in southeastern Norway was unhindered by beavers. In a restored, third-order stream in northern Nova Scotia, beaver dams generally posed no barrier to Atlantic salmon migration except in
10752-524: The process again in another year with 5–10% returning to the sea to spawn again. Such individuals can grow to extremely large sizes, although they are rare. The different life stages of the fish are known by many different names in English: alevin , fry , parr and smolt . Atlantic salmon is considered a very healthy food and one of the fish with a more refined taste in many cultures. As such it features in numerous popular traditional cuisines and can fetch
10864-794: The rates of Atlantic salmon mortality at sea more than doubled in the western Atlantic. Rivers of the coast of Maine , southern New Brunswick and much of mainland Nova Scotia saw runs drop precipitously, and even disappear . An international effort to study the increased mortality rate was organized by the North Atlantic Salmon Conservation Organization . In 2000 the numbers of Atlantic salmon dropped to very low levels in Newfoundland , Canada. In 2007 at least one sport fishing organization from Iceland and Scandinavia blamed less fish caught by recreational anglers on overfishing at sea, and thus created
10976-615: The region were ultimately unsuccessful. 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
11088-487: The result of misclassification leading to questions on whether there really are any ring species. The commonly used names for kinds of organisms are often ambiguous: "cat" could mean the domestic cat, Felis catus , or the cat family, Felidae . Another problem with common names is that they often vary from place to place, so that puma, cougar, catamount, panther, painter and mountain lion all mean Puma concolor in various parts of America, while "panther" may also mean
11200-586: The ring. Ring species thus present a difficulty for any species concept that relies on reproductive isolation. However, ring species are at best rare. Proposed examples include the herring gull – lesser black-backed gull complex around the North pole, the Ensatina eschscholtzii group of 19 populations of salamanders in America, and the greenish warbler in Asia, but many so-called ring species have turned out to be
11312-493: The river where they are born and the sea surface currents that are connected to that river in a circular path. Wild salmon continued to disappear from many rivers during the twentieth century due to overfishing and habitat change. 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
11424-508: The same species. This concept was narrowed in 2006 to a similarity of 98.7%. The average nucleotide identity (ANI) method quantifies genetic distance between entire genomes , using regions of about 10,000 base pairs . With enough data from genomes of one genus, algorithms can be used to categorize species, as for Pseudomonas avellanae in 2013, and for all sequenced bacteria and archaea since 2020. Observed ANI values among sequences appear to have an "ANI gap" at 85–95%, suggesting that
11536-529: The same species. When two species names are discovered to apply to the same species, the older species name is given priority and usually retained, and the newer name considered as a junior synonym, a process called synonymy . Dividing a taxon into multiple, often new, taxa is called splitting . Taxonomists are often referred to as "lumpers" or "splitters" by their colleagues, depending on their personal approach to recognising differences or commonalities between organisms. The circumscription of taxa, considered
11648-426: 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. 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. In addition,
11760-506: The species concept and making taxonomy unstable. Yet others defend this approach, considering "taxonomic inflation" pejorative and labelling the opposing view as "taxonomic conservatism"; claiming it is politically expedient to split species and recognise smaller populations at the species level, because this means they can more easily be included as endangered in the IUCN red list and can attract conservation legislation and funding. Unlike
11872-541: The species supported an important commercial fishery, but having become endangered throughout its range globally, wild-caught Atlantic salmon are now virtually absent from the market. Instead, nearly all are from aquaculture farms, predominantly in Norway, Chile, Canada, the UK, Ireland, Faroe Islands , Russia and Tasmania in Australia. Adult male and female fish are anaesthetised ; their eggs and sperm are "stripped" after
11984-530: The species was declared extirpated from the lake. 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. Beginning around 1990,
12096-428: The species' southern populations in northern Spain are growing smaller. The species distribution is easily influenced by changes in freshwater habitat and climate. Atlantic salmon are a cold-water fish species and are particularly sensitive to changes in water temperature. The Housatonic River , and its Naugatuck River tributary, hosted the southernmost Atlantic salmon spawning runs in the United States. However, there
12208-616: 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
12320-435: 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. Atlantic salmon is a popular fish for human consumption and
12432-540: The wild. It is difficult to define a species in a way that applies to all organisms. The debate about species concepts is called the species problem. The problem was recognised even in 1859, when Darwin wrote in On the Origin of Species : I was much struck how entirely vague and arbitrary is the distinction between species and varieties. He went on to write: No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of
12544-694: Was further compromised. According to historian D.W. Dunfield (1985) "over half of the historical Atlantic salmon runs had been lost in North America by 1850". As early as 1798, a bill for the preservation of Atlantic Salmon was introduced in Canadian Parliament, to protect populations in Lake Ontario. In the Gulf Region of Nova Scotia it was reported that 31 of the 33 Atlantic salmon streams were blocked off by lumber dams, leading to
#314685