Capelin stock in the Barents Sea (Mallotus villosus)

Capelin on white background.
Photo: Institute of Marine Research

Capelin are an important food source for fish, seabirds and marine mammals and are accordingly considered to be a key species in the Barents Sea. The stock undergoes large natural fluctuations.

What is being monitored?

The capelin stock in the Barents Sea

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The graph shows calculated sizes of immature stock and mature stock (spawning stock) of capelin in the Barents Sea. Together, this constitutes the total population.

Status and trend

The capelin stock was measured at 1.72 million tonnes in September 2020, of which the mature stock comprised 0.55  million tonnes. This mature stock is estimated to amount to around 0.16 million tonnes at spawning time in the spring of 2021. This stock level does not justify opening the capelin fishery in 2021.

Causal factors

The capelin stock undergoes large fluctuations, even in the absence of human impact such as fishing. This may be explained by capelin being short-lived (typically 3-4 years) and normally subject to strong predation by other fish, sea birds and sea mammals. This applies to both capelin fry and adult fish.

In 2015, the stock was considered collapsed for the fourth time since 1983. In 2017, measurements showed that the stock was once again large enough to allow for fishing. During the 2018 winter, 195 000 tonnes were caught. The results from 2018 showed a slight stock decline, while the results from 2019 indicated a stock below the 2015 level. Capelin recruitment has been weak for the previous six years, but this year was the strongest since 2013. The Joint Norwegian-Russian Fisheries Commission, which determines the fishing quota for capelin stocks, made the recommendation for null quota in 2021.

Consequences

Fluctuations and collapses in the capelin stock have previously caused domino effects in the Barents Sea ecosystem.

Collapses of the capelin stock in the 1980s had major consequences for predators that feed on capelin, such as cod and harp seals. It was observed that cod had reduced growth, delayed maturation and individuals were leaner. Cod changed their diet and started to eat less nutritious foods such as crustaceans, and cannibalism became more widespread in that cod ate codlings. Food shortage caused Harp seals to embark on large feeding migrations both southwards and westwards, which among other things led to 77,000 harp seals drowning in nets along the Norwegian coast in 1987–1988. Collapses in the capelin stock in recent times have not had the same ecosystem consequences, possibly because predators have had access to better alternative food sources.

About the monitoring

The indicator describes the size of the mature part of the capelin stock and its changes over time. The Norwegian Institute of Marine Research and the Russian Institute of Marine Research update the time series every autumn, based on a joint cruise with several vessels. This has been going on since 1973.

The International Council for the Exploration of the Sea (ICES) uses these data series to provide its stock assessment.

The size of the mature part of the capelin stock is used in a well-established management system under the operation of the Joint Norwegian-Russian Fisheries Commission, following the advice of ICES.

It should be considered whether the total population of capelin should be used as an indicator for the future. The total population will better show the role of capelin as a key species in the ecosystem, both as grazing on zooplankton and as prey for fish and mammals.

Places and areas

Relations to other monitoring

Monitoring programme
International environmental agreements
Voluntary international cooperation
Related monitoring