The capelin or caplin (Mallotus villosus) is a small forage fish of the smelt family found in the North Atlantic, North Pacific and Arctic oceans.[1] In summer, it grazes on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat a great deal of krill and other crustaceans. Among others, whales, seals, Atlantic cod, Atlantic mackerel, squid and seabirds prey on capelin, in particular during the spawning season while the capelin migrate south. Capelin spawn on sand and gravel bottoms or sandy beaches at the age of two to six years. When spawning on beaches, capelin have an extremely high post-spawning mortality rate which, for males, is close to 100%. Males reach 20cm (8in) in length, while females are up to 25.2cm (10in) long.[1] They are olive-coloured dorsally, shading to silver on sides. Males have a translucent ridge on both sides of their bodies. The ventral aspects of the males iridesce reddish at the time of spawn.
Migration of Icelandic capelin Green shade: Feeding area of adults Blue shade: Distribution of juveniles Green arrows: Feeding migrations Blue arrows: Return migrations Red shade and Red arrows: Spawning migrations, main spawning grounds and larval drift routesAtlantic puffin with capelin in its mouth
Capelin populations in the Barents Sea and around Iceland perform extensive seasonal migrations. Barents Sea capelin migrate during winter and early spring to the coast of northern Norway (Finnmark) and the Kola Peninsula (Russia) for spawning. During summer and autumn, capelin migrate north- and north-eastward for feeding.[2]
Icelandic capelin move inshore in large schools to spawn and migrate in spring and summer to feed in the plankton-rich oceanic area between Iceland, Greenland, and Jan Mayen. Capelin distribution and migration is linked with ocean currents and water masses. Around Iceland, maturing capelin usually undertake extensive northward feeding migrations in spring and summer, and the return migration takes place in September to November. The spawning migration starts from north of Iceland in December to January. In 2009, researchers from Iceland made an interacting particle model of the capelin stock around Iceland, successfully predicting the spawning migration route for the previous year.[3]
Reproduction
As an r-selected species, capelin have a high reproductive potential and an intrinsic population growth rate.[4] They reproduce by spawning and their main spawning season occurs in spring but can extend into the summer. The majority of capelin are three or four years old when they spawn.[2] The males migrate directly to the shallow water of fjords, where spawning will take place, while the females remain in deeper water until they are completely mature. Once the females are mature, they migrate to the spawning grounds and spawn.[5] This process usually takes place at night.[2] In the North European Atlantic spawning typically occurs over sand or gravel at depths of 2to 100m (7–328ft),[6] but in the North Pacific and waters off Newfoundland most spawn on beaches, jumping as far up land as possible, with some managing to strand themselves in the process.[4][7] Although some other fish species leave their eggs in locations that dry out (a few, such as plainfin midshipman, may even remain on land with the eggs during low tide) or on plants above the water (splash tetras), jumping onto land en masse to spawn is unique to the capelin, grunions, and grass puffer.[8][9] In beach-spawning capelin populations, after the female capelins have spawned, they immediately leave the spawning grounds and can spawn again in the following years if they survive. The males do not leave the spawning grounds and potentially spawn more than once throughout the season.[5] Beach-spawning male capelin are considered to be semelparous because they die soon after the spawning season is over.[2] In ocean spawning capelin populations, it has been observed that both male and female capelin are semelparous and die after spawning.[10] This difference observed between capelin populations shows that capelin are physiologically capable of an iteroparous or semelparous reproductive mode depending on spawning habitat.[10]
Studies on two populations of Newfoundland capelin which spawn in two distinct habitats found a lack of evidence of genetic variability between beach and deep-water spawners.[11] This provides support for the species being facultative spawners. Capelin may select optimal spawning location based on abiotic factors such as temperature range and sediment.[12] The optimal temperature range for capelin eggs that leads to greatest hatching success and offspring quality appears when eggs are incubated between 5°C and 10°C.[12] This optimal temperature range provides support that individual capelin are able to select spawning location based on temperature, as temperature is one of the most variable factors between beach and deep-water spawning habitats for capelin.[12] There is also evidence that shows that temperature is not the only factor at play when it comes to selection of spawning habitat. When both habitats are simultaneously experiencing temperatures in the optimal range, capelin are found to spawn in both habitats.[11] This may be an advantageous strategy that leads to increased fitness.[11] Capelin have been observed to spawn at beaches when deep-water or subtidal habitat is lower than 2°C and spawn in deep-water habitats when beach habitats temperature is consistently above 12°C.[12]
Diet
Capelin are planktivorous fishes that forage in the pelagic zone.[13] Studies analyzing diet in populations of Capelin in both the arctic marine environment as well as in west Greenland waters show that their diet consists upon primarily euphausiids, amphipods, and copepods.[14][13] As capelin individuals grow, the composition of their diet changes.[14] Smaller capelin primarily consume smaller prey (copepods) and shift their diet towards feeding on primarily larger euphausiids and amphipods as body and gape size increases.[14][13] The sufficient distribution and abundance of these zooplankton is necessary for capelin to meet energy requirements for progressing through many stages of their life cycle.[13] Capelin occupy a similar dietary niche as polar cod, which leads to a potential for interspecific competition between the two species.[13]
Fisheries
Global capture of capelin in tonnes reported by the FAO, 1950–2010
Capelin is an important forage fish, and is essential as the key food of the Atlantic cod. The northeast Atlantic cod and capelin fisheries, therefore, are managed by a multispecies approach developed by the main resource owners Norway and Russia.
In some years with large quantities of Atlantic herring in the Barents Sea, capelin seem to be heavily affected. Probably both food competition and herring feeding on capelin larvae lead to collapses in the capelin stock. In some years, though good recruitment of capelin despite a high herring biomass suggests that herring are only one factor influencing capelin dynamics.
In the provinces of Quebec (particularly in the Gaspé peninsula) and Newfoundland and Labrador in Canada, it is a regular summertime practice for locals to go to the beach and scoop the capelin up in nets or whatever is available, as the capelin "roll in" in the millions each year at the end of May or in early June.[16]
Commercially, capelin is used for fish meal and oil industry products, but is also appreciated as food. The flesh is agreeable in flavour, resembling herring. Capelin roe (masago) is considered a high-value product in Japan. It is also sometimes mixed with wasabi or green food colouring and wasabi flavour and sold as "wasabi caviar". Often, masago is commercialised as ebiko and used as a substitute for tobiko, flying fish roe,[17] owing to its similar appearance and taste, although the mouthfeel is different due to the individual eggs being smaller and less crunchy than tobiko.
1 2 3 4 Gjøsæter, H. (1998). "The population biology and exploitation of capelin (Mallotus villosus) in the Barents Sea". Sarsia. 83 (6): 453–496. doi:10.1080/00364827.1998.10420445.
The Norwegian Sea is a marginal sea, grouped with either the Atlantic Ocean or the Arctic Ocean, northwest of Norway between the North Sea and the Greenland Sea, adjoining the Barents Sea to the northeast. In the southwest, it is separated from the Atlantic Ocean by a submarine ridge running between Iceland and the Faroe Islands. To the north, the Jan Mayen Ridge separates it from the Greenland Sea.
Cod is the common name for the demersal fish genus Gadus, belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus Gadus is commonly not called cod.
The Atlantic cod is a fish of the family Gadidae, widely consumed by humans. It is also commercially known as cod or codling. Dry cod may be prepared as unsalted stockfish, and as cured salt cod or clipfish.
Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Such migrations are usually done for better feeding or to reproduce, but in other cases the reasons are unclear.
The haddock is a saltwater ray-finned fish from the family Gadidae, the true cods. It is the only species in the monotypic genus Melanogrammus. It is found in the North Atlantic Ocean and associated seas, where it is an important species for fisheries, especially in northern Europe, where it is marketed fresh, frozen and smoked; smoked varieties include the Finnan haddie and the Arbroath smokie. Other smoked version include long boneless, the fileted side of larger haddock smoked in oak chips with the skin left on the fillet.
The thick-billed murre or Brünnich's guillemot is a bird in the auk family (Alcidae). This bird is named after the Danish zoologist Morten Thrane Brünnich. The very deeply black North Pacific subspecies Uria lomvia arra is also called Pallas' murre after its describer. The genus name is from Ancient Greek ouria, a waterbird mentioned by Athenaeus. The species term lomvia is a Swedish word for an auk or diver. The English "guillemot" is from French guillemot probably derived from Guillaume, "William". "Murre" is of uncertain origins, but may imitate the call of the common guillemot.
Sebastes norvegicus, the rose fish, rock fish, ocean perch, Atlantic redfish, Norway haddock, golden redfish, pinkbelly rosefish or bergylt, is a species of marine ray-finned fish belonging to the subfamily Sebastinae, the rockfishes, part of the family Scorpaenidae. It is found in the North Atlantic Ocean. It is a large, slow-growing, late-maturing fish and the subject of a fishery.
The harp seal, also known as Saddleback Seal or Greenland Seal, is a species of earless seal, or true seal, native to the northernmost Atlantic Ocean and Arctic Ocean. Originally in the genus Phoca with a number of other species, it was reclassified into the monotypic genus Pagophilus in 1844. In Greek, its scientific name translates to "ice-lover from Greenland," and its taxonomic synonym, Phoca groenlandica translates to "Greenlandic seal." This is the only species in the genus Pagophilus.
Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that live on or near the bottom, and reef fish that are associated with coral reefs.
Cyclopterus is a genus of marine ray-finned fish belonging to the family Cyclopteridae, the lumpsuckers or lumpfish. Its only species is Cyclopterus lumpus, the lumpsucker or lumpfish. It is found in the North Atlantic and adjacent parts of the Arctic Ocean, ranging as far south as Chesapeake Bay on the North American coast and Spain on the European coast. The species has been reported twice in the Mediterranean Sea, off Croatia in 2004 and Cyprus in 2017.
The Atlantic halibut is a flatfish of the family Pleuronectidae. They are demersal fish living on or near sand, gravel or clay bottoms at depths of between 50 and 2,000 m. The halibut is among the largest teleost (bony) fish in the world, and is a threatened species owing to a slow rate of growth and overfishing. Halibut are strong swimmers and are able to migrate long distances. Halibut size is not age-specific, but rather tends to follow a cycle related to halibut abundance.
The Greenland halibut or Greenland turbot belongs to the family Pleuronectidae, and is the only species of the genus Reinhardtius. It is a predatory fish that mostly ranges at depths between 500 and 1,000 m (1,600–3,300 ft), and is found in the cold northern Atlantic, northern Pacific, and Arctic Oceans.
Animal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migration in ecology. It is found in all major animal groups, including birds, mammals, fish, reptiles, amphibians, insects, and crustaceans. The cause of migration may be local climate, local availability of food, the season of the year or for mating.
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, to spawn refers to the process of freely releasing eggs and sperm into a body of water ; the physical act is known as spawning. The vast majority of non-mammalian, non-avian and non-reptilian aquatic and/or amphibious lifeforms reproduce through this process, including the:
Forage fish, also called prey fish or bait fish, are small pelagic fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding. They include particularly fishes of the order Clupeiformes, but also other small fish, including halfbeaks, silversides, smelt such as capelin and goldband fusiliers.
Cod fisheries are fisheries for cod. Cod is the common name for fish of the genus Gadus, belonging to the family Gadidae, and this article is confined to three species that belong to this genus: the Atlantic cod, the Pacific cod and the Greenland cod. Although there is a fourth species of the cod genus Gadus, Alaska pollock, it is commonly not called cod and therefore currently not covered here.
In biology, any group of fish that stay together for social reasons are shoaling, and if the group is swimming in the same direction in a coordinated manner, they are schooling. In common usage, the terms are sometimes used rather loosely. About one quarter of fish species shoal all their lives, and about one half shoal for part of their lives.
Illex illecebrosus, commonly known as the northern shortfin squid, is a species of neritic squids in the family Ommastrephidae. Squids of the genus Illex account for 65% of the world's cephalopod captures. Illex is formed by four taxa distributed throughout the Atlantic Ocean, whose identification and phylogenetic relationships based on morphological characters remain controversial.They are found in the northwest Atlantic Ocean, from off the coast of eastern North America to Greenland, Iceland, and west of Ireland and the United Kingdom. They are a highly migratory and short-lived species, with lifespans of less than a year. They are commercially important and are fished extensively, mostly for the Canadian and Japanese markets.
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton. Planktivory can be an important mechanism of top-down control that contributes to trophic cascades in aquatic and marine systems. There is a tremendous diversity of feeding strategies and behaviors that planktivores utilize to capture prey. Some planktivores utilize tides and currents to migrate between estuaries and coastal waters; other aquatic planktivores reside in lakes or reservoirs where diverse assemblages of plankton are present, or migrate vertically in the water column searching for prey. Planktivore populations can impact the abundance and community composition of planktonic species through their predation pressure, and planktivore migrations facilitate nutrient transport between benthic and pelagic habitats.
The Iceland Sea is a small body of water delimited by the Jan Mayen fracture zone to the north, Greenland to the west, the Denmark Strait to the south, and the Jan Mayen Ridge to the east. Depths usually range from 500 to 2,000 meters but can be shallower on the Continental shelf of East Greenland. The Kolbeinsey Ridge crosses the Iceland Sea, dividing it into eastern and western parts.
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