Capelin

Capelin are small, elongated, and silvery marine fishes of the genus Mallotus (family Osmeridae, order Salmoniformes). Capelin play a key role in the North Atlantic Subarctic ecosystem as a food source for cod, haddock, redfishes, plaice, seabirds, and marine mammals. There is one species with two subspecies: Mallotus villosus villosus of the North Atlantic Ocean and Mallotus villosus catervarius of the North Pacific Ocean, both distributed in cool temperate and Subarctic waters. Capelin are practically absent along the Siberian coast, and present discontinuously in the Canadian Arctic; the Arctic populations are probably relicts from preceding warm periods.

M. v. villosus (the North Atlantic population) is distributed along the Norwegian coast, northward to Spitsbergen, Novaya Zemlya, White and Barents seas,

Masses of capelin dead on a beach after breeding, Newfoundland, Canada.

Copyright Bryan and Cherry Alexander Photography

Masses of capelin dead on a beach after breeding, Newfoundland, Canada.

Copyright Bryan and Cherry Alexander Photography also Jan Mayen Island, Faroe Islands, Iceland, and Greenland north to Ittoqqortoormiit (Scoresbysund), and in the western North Atlantic southward to Maine. Body length can be up to 22 cm, rarely to 25 cm. The habitat is littoral to neritic (water column over the continental shelf) and benthic (living on the ocean bottom) on fishing banks down to 300 m, and they feed on planktonic crustaceans. North Atlantic capelin form shoals and migrate to coastal spawning areas from spring to autumn. There are two different spawning populations, in two habitats: on intertidal beaches (in the western North Atlantic with the exception of the population on the Grand Banks) and on subtidal sediments offshore (mainly in the Barents Sea with some minor stocks in some Norwegian fjords, the White Sea, and around Iceland). In the western Atlantic, capelin are found on offshore banks and in coastal areas, occasionally spending the winter and early spring months in deep bays. The largest concentrations in Canadian waters are found off Newfoundland and the Labrador coast.

Mass spawning takes place from the age of three to four years. On the south and east coast of Newfoundland and Labrador, spawning begins around the first part of June and may continue through July and August depending on tides, winds, and water temperature.

Beach-spawning capelin spawn on coarse sand or fine gravel, where the eggs are buried by wave action and are presumably safe from flushing by tidal exchange and from predation while development takes place. Substrate characteristics of capelin-spawning beaches are specific, and pebble diameter varies from 5-15 mm (at Holyrood Beach, Newfoundland) to 1-4 mm (at Bryant's Cove, Newfoundland). The capelin spawn during an ebbing tide at or near the period of maximum tidal range. Surface water temperature ranges from 5.6°C to 10.8°C, average 6.2-7.3°C (east coast of Newfoundland). Usually two waves of spawning take place at the same spawning ground, with an interval of 12-15 days. Offshore spawning also occurs at a depth from 2-3 to 46-49 m. Here, bottom water temperatures are about 2.8-4.2°C. Capelin in spawning condition are found offshore on various banks at depths up to 80 m.

Mating on beaches is most intensive during a period of intermediate tide. Spawning takes place at night or during times of heavy overcast and ceases during sunlight hours. Rolling and swimming inshore near the crest of the waves, the gravid females and males are brought onto the beaches where the eggs are deposited and fertilized on the substrate. The male can be observed to press against the side of the female, and often a second male takes a position on the opposite side of the female. Eggs, which are spherical, demersal, adhesive, and with an average diameter of about 1 mm, can be buried 15 cm or more beneath the surface of the beach. They become attached to beach gravel or to the bottom substrate, where they develop and hatch. The number of eggs produced increases with the size of the female, and may be up to 50,000.

Spent fish appear immobile for a short period before reentering the water with the following waves, and may sometimes become stranded. Mass mortalities occur, leading to the mistaken belief that capelin may spawn only once. But there is evidence of repeated spawning by some females.

The specificity of beach spawning sites used by capelin results in dense concentrations of eggs (>800/cm2) in the beach gravel. Egg mortalities vary annually with changes in biological, meteorological, and hydrological conditions. Lack of oxygen resulting from high egg density, water and air temperature effects, substrate characteristics, amount of rainfall, and accumulation of excretory products are hypothesized to affect egg development and egg mortality.

Hatching occurs in the beach sediments after 9-11 days in the high-tide zone and 22-24 days in the low-tide zone, depending on incubation temperature. The emergence of capelin larvae from the beach gravel, and the onset of larval drift, is episodic and closely correlated with the occurrence of onshore winds. Onshore winds drive warmer, food-reach, predator-poor surface waters into the nearshore waters. Larvae emerge actively in response to the sharp temperature increases caused by this water mass exchange and thus become associated with a favorable predator/prey field. Onshore water mass exchange occurs synchronously over large areas of Newfoundland's east coast in response to large-scale atmospheric systems. Larval emergence is therefore synchronous over large geographical areas.

Dispersal of the larvae is initially passive, but is later moderated by active vertical migrations. The migratory pattern of this species in early life brings them inshore and near the surface in early summer and offshore into deeper waters in autumn.

At age 1+, the average length of capelin is about 87 mm. Males grow faster than females until they reach maturity, after which the rate of growth is approximately the same. There is a general north-south cline. Those from the Grand Bank and southern Newfoundland areas grow more quickly than those from the Labrador area until a similar maximum size is attained. Labrador capelin tend to mature one year later than those from the Grand Bank. The majority of capelin do not live longer than five years, but in Greenland, where the growth rate is slower, seven-year-old fish are known. The length of mature specimens is generally 13-20 cm. The largest capelin recorded was a five-year-old female, 25.2 cm in total length, weighing 59 g, captured in Trinity Bay, Newfoundland.

In the Barents Sea, the Pacific capelin (M. v. cater-varius) mature at ages of two to four years, mainly three years, at a length of 15-19 cm. During summer and autumn, the adult capelin feed in the northern part of the Barents Sea. The feeding area shifts in the east-west direction in response to climatic variations. The Barents Sea capelin make annual spawning migrations from northern areas of the Barents Sea to the coastal zone. Three waves occur: (1) spring-spawning capelin (majority of age three to four years) spawn in March-May mainly from Finnmark to West Murman, but also (in years of high density) eastward to Kharlov Island and Cap Svyatoy Nos; (2) summer-spawning (Murman) capelin (of age two to three years) spawn in June-July, with intervals to August, mainly along East Murman, in the entrance to the White Sea (Gorlo) and in Cheshskaya Bay, but also westward along the whole Murman coast and in the Voronka of the White Sea; (3) autumn-spawning (Novaya Zemlya) capelin spawn in August-September irregularly at the west coast of Novaya Zemlya and Cheshskaya Bay (eastern limits of spawning area). Spawning takes place on offshore sediments at a depth from 30 to 130 m, and a large number of capelin die after spawning.

Capelin is an important subsistence catch in some indigenous communities, and the Ammassalik area in East Greenland takes its name from "the place of the capelin," where large numbers of capelin have always spawned on the beach, leaving many stranded and easy to harvest each year. It is also an important commercial fish. The mean annual total capelin catch from 1965 to 1984 was 1,994,164 tons. The total catch of capelin peaked in 1977 at 4,000,000 tons and ranked second in world catch production. Capelin continue to play an important role in the North Atlantic fishery. In the Barents Sea, the catch was 1.6-2.3 million tons in 1977-1984; in the mid-1980s, the stock catastrophi-cally decreased and fishery was forbidden until 1990.

At present, the Barents Sea population of capelin is in a depressed state and fishery here is controlled and strictly limited.

Natalia V. Chernova

See also Fish

Further Reading

Stergiou, Konstantinos I., "Capelin Mallotus villosus (Pisces: Osmeridae), glaciation, and speciation: a nomothetic approach to fisheries ecology and reproductive biology." Marine Ecology Progress Series, 56 (1989): 211-224

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