Fishing mortality in the Barents Sea
Last updated 21 April 2023
Fishing mortality gives an estimate of how much of the population is caught. caught. It is caught large quantities of fish in the Barents Sea, and today, the stocks are managed sustainably. The Barents Sea is an important fishing area, where there is caught large quantities of primarily cod, haddock, capelin as well as some shrimp, Greenland halibut and beaked redfish.
What is being monitored?
Fishing mortality in the Barents Sea
The figure shows the development in fishing mortality for cod, haddock and beaked redfish in the Barents Sea. Fish mortality indicates what proportion of the fish stocks that are catched. Where the value in the diagram is lower than zero, the fish mortality is lower than the adopted limit and the stock is harvested sustainably.
(Cite these data: Institute of Marine Research (2023). Fishing mortality in the Barents Sea. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL: https://mosj.no/en/indikator/influence/fishery-and-freshwater-fishing/fishing-mortality-in-the-barents-sea/)
Details on these data
| Last updated | 21 April 2023 |
| Update interval | Yearly |
| Next update | August 2024 |
| Commissioning organization | Ministry of Trade, Industry and Fisheries |
| Executive organization | Norwegian Institute of Marine Research |
| Contact persons | Gro I. van der Meeren (The monitoring group’s secretariat) Bjarte Bogstad |
Method
Fishing mortality due to fisheries is one of several mortality factors for fish. The instantaneous total mortality rate (Z) is calculated from a clearly defined formula, where the mortality rate for a year class of fish one year is determined by the number of fish at the start of the year and the number of fish at the start of the following year. Total mortality is all the mortality in the stock and is therefore a measure of how many fish disappear from a given year class during the year.Total mortality can be divided into two:
1. Mortality (F) as a result of fishing
2. Natural mortality (M) as a result of predation, disease etc.
Fishing mortality for a species is thus a complicated measure for several year classes. For example, in the case of cod, an average of the annual classes from 5 to 10 years, designated as F5–10, is often used. However, it is not easy to select certain year classes over others as fishing mortality varies with age and size of fish. Young fish have the highest mortality rates, although they are not fished to any great extent and can thus have low fishing mortality, but high natural mortality.
The fishing mortality (F) is usually between 0 and 1, and is proportional to the catch effort. A doubling of F is almost a doubling of the catch effort.
The following factors are included in the measurements: Critical spawning stock level (Blim), the precautionary reference point for spawning stock biomass (Bpa) and B-target, the spawning stock level one are aiming for/ trying to achieve. Critical fishing mortality level (Flim), the precautionary reference point for fishing mortality (Fpa) and fishing mortality consistent with achieving Maximum Sustainable Yield (FMSY). “About the monitoring” gives more information on these terms.
Flim is the upper limit for F to ensure sustainable fisheries. When advice is offered, the F value is usually given as FMSY. If there is negative development in both the stock and recruitment, and the fishing mortality remains below the reference value over time, measures are taken to protect the stock and reduce the fishing mortality. For instance, quotas will be regulated.
| Fish stock | Survey | Method | ICES-working group |
|---|---|---|---|
| Northeast Arctic cod | Joint Barents Sea survey in August-September (ecosystem survey) and February (winter survey), Russian bottom trawl autumn survey in October-December. Lofoten survey. | Bottom trawl | AFWG |
| Northeast Arctic haddock | Joint Barents Sea survey, bottom trawl in August-September (ecosystem survey) and February (winter survey), Russian bottom trawl autumn survey in October-December. | Bottom trawl | AFWG |
| Beaked redfish | Joint Barents Sea survey, bottom trawl in August-September (ecosystem survey) and February (winter survey), and pelagic survey in the Barents Sea and the Norwegian Sea every third year. | Bottom trawl | AFWG |
Terms
- Blim = Limit reference point for spawning stock biomass
- Bpa = Precautionary reference point for spawning stock biomass
- Flim = Limit reference point for fishing mortality
- Fpa = Precautionary reference point for fishing mortality
- Fmp = Fishing mortality reference point as defined in management plans
- FMSY = Fishing mortality consistent with achieving maximum sustainable yield
- F = Instantaneous rate of fishing mortality
- Z = Total mortality
- M = Natural mortality
Quality
The monitoring is not certified, but the methods used are quality assured and to a large degree coordinated between Norway and Russia. Data are collected in several contexts, and data from the commercial fishery origins both from fishery reports and statistics from the Directorate of fisheries.
The indicator applies only to fishing mortality for cod, haddock and beaked redfish in the management plan area of the Barents Sea.
Other metadata
Reference level and action level
The stocks are managed mainly in accordance with agreed management plans, which include a harvesting regulation defining how fishing mortality must be reduced when the spawning stock biomass falls below a certain level.
To ensure sustainable fisheries, a critical limit for fishing mortality for many fish stocks (Flim) has been set. In recent years, however, the fishing mortality that is expected to produce the maximum sustainable yield of fisheries (Fmsy) has become governing when the International Council of the Sea (ICES) provide countries advice on sizes of fishing quotas. The indicator is based on the actual deviation in estimated fishing mortality (F) related to the recommended Flim.
Deviations between the calculated actual fishing mortality for the species, and critical fishing mortality level (Flim) recommended by ICES, is calculated with 95% uncertainty, but not presented here. For some species the precautionary value Fpa is recommended. This is used in variance calculation when Flim is not given.
Limit reference point – fishing mortality
| Fish species | Critical limit reference point for highest accetable fishing mortality | Last changed |
|---|---|---|
| Northeast Arctic cod (5-10 years) | Flim=0.74 | 2015 |
| Northeast Arctic haddock (4-7 years) | Flim=0.77 | 2015 |
| Beaked redfish | FMSY=0.039 | 2006 |
| Greenland halibut | Not defined | Not carried out |
| Capelin | Not defined | Not carried out |
Action level
The stocks included in this indicator are mainly managed by management plans. The harvest rule defines how fishing mortality must be reduced when the size of the spawning population goes below a certain level.
Status and trend
A review of catch statistics for Norwegian and foreing vessels in recent years shows that Norway accounts for approximatley 45 % of all catches in the Barents Sea, while Russia, Iceland, Greenland, Great Britain, the Faroe Islands and EU countries account for the remaing.
Throughout history, fisheries have had a clear impact on commercial stocks with following impacts on the ecosystems. Fishing mortality is a measure of the proportion of fish stocks that are fished. The extent of fishing mortality is included in the assessments made when determining fishing quotas and harvesting rules. The data is gathered from calculations by the International Council for the Exploration of the Sea (ICES).
The status for all the stocks is good, as they have been harvested sustainably in many years. In the last years, fishing mortality have increased for both cod and haddock, and is now above the precautionary level. However, the spawning population for those species is well above the precautionary level.
Causal factors
The fishing mortality is affected by the amount of fish landed by the fisheries and is thus related to the harvest rate. If the fishing mortality is calculated to be below the precautionary value (Fpa), the stock is harvested sustainably
Consequences
Fishing mortality is an important part of the quota agreements. In the case where a fish stock undergo low development rate, the fisheries will receive smaller quotas and it may also lead to extended time- and area restrictions for the fisheries.
The capelin stock is an exception and has greatly declined from 2013 to 2016. The capelin fishing was closed from 2016-2020 (except in 2018) but was opened again in 2022 and 2023. The capelin’s short life span and the fact that it is a one-time-spawner makes the calculation method for fishing mortality not suitable for this species.
The stocks of cod and capelin are managed in context, taking account of the cod grazing on capelin and the capelin’s importance as food for cod. Capelin fishing has also been stopped several times previously (1987-1990, 1994-1998, 2003-2007). Impact on capelin stocks from cod, herring and other species are believed to be greater than from fishing.
About the monitoring
This indicator is based on the deviation in calculated, actual yearly fishing mortality for each species, subtracted from the given absolute upper limit for fishing mortality (Flim), recommended by the International Council for the Exploration of the Sea (ICES). The precautionary reference point (Fpa) is used if Flim is not given.
Fishing mortality is used together with stock size and recruitment rates as a management tool to regulate fishing pressure on the commercial stocks.
The indicator includes fishing mortality for cod, haddock, and beaked redfish. Limit reference for fishing mortality is not calculated for other important commercial stocks and are therefore not presented here. Capelin, that only spawn once, is managed so that there is a 95% probability that the spawning population is above the limit reference point for spawning stock biomass (Blim). And since fishing mortality is not used in management of caplin, it is not presented in this indicator.
This indicator says something about the extent to which the commercial fish stocks in the Barents Sea are directly affected by the fisheries. And it is used in fisheries management.
The size of fishing mortality is included in the assessments that are made when fishing quotas and harvesting rules are determined. The data is collected from the International Council for the Exploration of the Sea (ICES).
Institute of Marine Research is collecting data from the Norwegian economic zone, the Fisheries Protection Zone around Svalbard, and to some extent from the Russian economic zone, to calculate population dynamics and recruitment in species such as cod, haddock, Greenland halibut and beaked redfish, capelin and partly polar cod. The data collection happens on yearly surveys, and many of these are in collaboration with Russia.
All participating countries goes together with fishery data and provides an overall assessment of population dynamics and fishing mortality, which gives the basis for the international quota advices from ICES. ICES gives advice on total quota based on fishing mortality and analysis on the size of the total stock, spawning stock, and year-class strength of all commercial fish stocks.
The stocks are jointly managed on advice from ICES through agreements between Norway and other countries. The total quota for cod, haddock, capelin, and Greenland halibut is decided by Norway and Russia. Norway and Russia have agreed upon harvesting rules for cod, haddock, and capelin.
Beaked redfish is fished both in the Barents Sea and the Norwegian Sea (international waters, the so-called “Banana Hole”), and separate quotas are set for these areas. There is no total quota set for shrimps, however, the catch has for many years been significantly below the recommendations from ICES.
Evaluation
A spawning stock which is calculated to be at a level that most likely will give good recruitment has good reproductive ability (the spawning stock is above Bpa). Good recruitment presupposes that environmental factors which influence fry survival are favourable.
When the level of the spawning stock is calculated to be such that there is increasing likelihood of it giving reduced recruitment, the stock is at risk of having reduced reproductive ability (the spawning stock is below Bpa, but above Blim). This, in turn, assumes that environmental factors are favourable for recruitment. Should the spawning stock be calculated to be at a level which in all probability will result in poor recruitment irrespective of environmental conditions, the stock is said to have an diminishing reproductive ability (the spawning stock is below Blim).
Fishing mortality is connected with the degree of harvesting. If the fishing mortality is calculated to be below the precautionary level (Fpa), the stock is said to be harvested sustainably. If the fishing mortality is calculated to be above the precautionary level (Fpa), but below what ICES has defined as the action limit for sustainability (Flim), there is a risk that the stock cannot be sustainably harvested. Then there is a greater likelihood that the fishing mortality is at a level which will lead the stock biomass below the precautionary level (Bpa). If the fishing mortality is calculated to be above the action limit for sustainability (Flim), the stock is not harvested sustainably.
Places and areas
Relations to other monitoring
Monitoring programme
- Norwegian Institute of Marine Research’s permanent monitoring programme for fish resources
Including the winter cruise, the spawning cod cruise, the 0-group cruise, the autumn capelin cruise and the larvae cruise.
International environmental agreements
- International Council for the Exploration of the Sea (ICES)
- Joint Fish – Joint Norwegian-Russian Fisheries Commission
Voluntary international cooperation
- None
Related monitoring
- None
Further reading
Links
- Fishing mortality in the Barents Sea on Environment.no (In Norwegian)
- Norwegian Institute of Marine Research (IMR) advice on quotas (in Norwegian)
Publications
- Bakketeig, I., Gjøsæter, H., Hauge, M., Sunnset, B. H., & Toft, K. Ø. (red.) (2015). Havforskningsrapporten 2015. Fisken og havet, særnummer 1-2015. Havforskningsinstituttet. https://doi.org/11250/280252.
- Ellingsen, K. E., Anderson, M. J., Shackell, N. L., Tveraa, T., Yoccoz, N. G., & Frank, K. T. (2015). The role of a dominant predator in shaping biodiversity over space and time in a marine ecosystem. Journal of Animal Ecology, 84(5), 1242-1252. https://doi.org/10.1111/1365-2656.12396
