Capelin stock in the Barents Sea (Mallotus villosus)
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?
Cite these dataInstitute of Marine Research (2022). Capelin stock in the Barents Sea. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL: http://www.mosj.no/en/fauna/marine/capelin.html
|Recruits||109||Institute of Marine Research||529||305||190||211||360||84||12||270||403||528||515||155||39||6||38||21||189||700||402||351||2||20||7||82||99||179||156||449||114||60||82||51||27||60||222||313||124||248||209||146||324||105||40||32||86||59||17|
|Mature stock||109 kg||Institute of Marine Research||1.35||0.91||2.92||3.2||2.68||1.4||1.23||3.91||1.55||1.59||1.33||1.21||0.29||0.07||0.02||0.2||0.18||2.62||2.25||2.23||0.33||0.09||0.12||0.25||0.31||0.93||1.72||2.1||2.02||1.29||0.28||0.29||0.17||0.44||0.84||2.47||2.32||2.05||2.12||2||1.47||0.87||0.38||0.18||1.72||1.06||0.31||0.55|
|Immature stock||109 kg||Institute of Marine Research||3.79||4.83||4.89||3.22||2.21||2.85||2.94||2.8||2.34||2.19||2.9||1.76||0.58||0.06||0.08||0.23||0.69||3.21||5.04||2.92||0.47||0.11||0.08||0.26||0.6||1.12||1.06||2.18||1.61||0.92||0.25||0.33||0.15||0.35||1.28||1.96||1.44||1.45||1.59||1.59||2.49||1.08||0.47||0.15||0.78||0.54||0.11||1.17|
The indicator is based on international advice from ICES.
The stock assessment and development are based on the measurements made during the annual Norwegian-Russian ecosystem cruise in the Barents Sea in September. This is an acoustic trawl that largely covers the entire capelin stock, and which provides an estimate of the amount of capelin and the composition of the stock.
The quantity estimate is made in the StoX software. In the stock assessment, the quantity estimate is used as an absolute estimate of the stock in the autumn, but since the fishing takes place the following winter and early spring, the stock is projected six months in time from the time the measurements take place. The projection is made using the Bifrost/ CapTool models, which use the quantity estimate from the cruise as input data, as well as calculations of maturation, growth and mortality (including grazing pressure of cod based on stock size, size composition and stomach samples). Assessment of uncertainty in cruise estimates and other input data are included in these model runs. In addition, FangstFisk is used to facilitate catch data.
Uncertainties related to the indicator depends on the accuracy and precision in the capelin stock assessment from the joint Norwegian- Russian cruise in September.
Reference level and action level
The reference level: None
The Norwegian-Russian Fisheries Commission has decided a management rule that states that there should be less than 5 percent probability that the spawning stock should be less than 200,000 tons at the time of spawning. ICES advices on capelin management based on this rule.
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.
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.
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