Fishing is the largest human impact on the fish stocks in the Barents Sea, and thereby on the functioning of the whole ecosystem. However, the observed variation in both fish species and ecosystem is also strongly affected by as climate and trophic interactions. During the last decade catches of most important commercial species in the Barents Sea and adjacent waters of Norwegian and Greenland Sea varied around 1.5–3 mill. tonnes and has decrease in the last years (Figure 220.127.116.11.).
Variation of catches in the region depends both on stock dynamics of species and management considerations. For all main species harvesting strategies are applied when setting TACs and also actual catches are very close to the agreed TACs.
Figure 18.104.22.168. Total catches of the most important stocks in the Barents Sea and adjacent waters of Norwegian and Greenland Sea (including catches in all of ICES area 2a, i.e. along the Norwegian coast south to 62N) from 1965 to 2016. Catches of Norwegian spring-spawning herring outside ICES area 2a are also included. Also minor catches of other stocks are taken in the Barents Sea (see ICES website).
* 2016 preliminary data.
Fishing mortalities and harvesting strategies
Fisheries influence the ecosystem by removing sustainable quantities of fish as food for humans and other purposes. The fishery is not considered sustainable if it impairs the recruitment of the fish stocks. Single species management often focuses on measuring the status of the fishery in relation to benchmarks called biological reference points (BRPs). BRPs for single species management are usually defined in terms of fishing mortality rate (F) and total or spawning-stock biomass (TSB or SSB) and in terms of target and limit reference points. Limit BRPs suggest maximum levels of F and minimum levels of B that should not be exceeded. These BRPs are then compared to estimates of F and B from stock assessments to determine the state of the fishery and suggest management actions.
The limit reference point for fishing mortality, Flim, will eventually bring the spawning stock down to Blim, below which the recruitment will be impaired. Flim may hence be used as an indicator for unsustainable exploitation and negative influence on the stock and the ecosystem. Keeping F below Flim and the stock above Blim may, however, not be considered as sufficient protection. Smaller and younger adults resulting from high fishing pressure have a lower reproductive potential than adults of a wider range of sizes and ages. The harvest rate and fishing pattern should hence fit with these biological requirements.
Recently the Maximum Sustainable Yield (MSY) concept was implemented in ICES work. The ICES approach to fisheries advice integrates the precautionary approach, maximum sustainable yield, and an ecosystem approach into one advisory framework. The aim is, in accordance with the aggregate of international guidelines, to inform policies on yields that can be taken out in the fisheries while maintaining productive fish stocks within healthy marine ecosystems. Maximum sustainable yield is a broad conceptual objective aimed at achieving the highest possible yield in the long term (an infinitely long period of time). For several stocks, MSY reference points have been identified and implemented in fishery management strategy.
Furthermore, a fishery may not be considered optimal if the fish are caught too early, i.e. if the net natural growth potential is not utilized. This is called growth overfishing and makes the total yield less than it would be if the fish were allowed to grow to a reasonable size. Introduction of minimum catch size and selective gears are the most common management measures to avoid growth overfishing.
Larvae and juveniles of all groundfish species are important predators on zooplankton. It is hence important for a sound ecosystem that there are sufficient plankton eaters present to utilize the plankton production and convert this into production of fish, both as food for humans, but also as food for other fish, marine mammals and seabirds that depend on fish prey. It is therefore not sufficient to manage the fish stocks to the extent that the recruitment is not impaired as seen from a single species point of view, but rather to maximize the larvae production as a valuable food contribution to the ecosystem as a whole.
Cod, haddock, and saithe
These stocks have F-based management plans which are largely followed by managers when setting TACs. All of these stocks are currently harvested close to or below MSY (Figure 22.214.171.124), and all of them are above Bpa at present. Several variants of harvest control rules for cod and haddock were tested by ICES in 2016. A new harvest control rule for cod, with increasing F at high stock sizes, was adopted by the joint Russian-Norwegian Fisheries commission in autumn 2016. The HCR for haddock was not changed. The current HCR for saithe was set by Norway in 2013.
Figure 126.96.36.199. Annual fishing mortalities of the northeast Arctic cod, haddock and saithe stocks relative to fisheries management plan (FMP), i.e. the level used in the management plans for these stocks when SSB > Bpa (ICES 2016). Note that saithe is mainly found along the Norwegian coast and off the coast south of the Barents Sea – little in the Barents Sea itself.
The exploitation rate has in some periods been critically high. Because of the harvest control rule and better control and enforcement, this problem seems to have been reduced in recent years. The recent increased exploitation rate of cod needs careful monitoring. Although the exploitation rate may have been too high to fully utilize the production potential in the stocks, it may be concluded that the exploitation of these three stocks since 2005 have been sustainable.
The current large cod stock has caused some concerns about it being ’too large’ as compared to food availability / carrying capacity. So far the cod population dynamics has been little affected by the stock size, but the question is certainly valid, and the introduction of a harvest control rule with increased fishing mortality at high stock sizes is a step towards taking such concerns into account. However, the concept of a stock being ’too large’ is not at present incorporated in the ICES advice framework, although such issues are well known e.g. in management of freshwater fisheries and wildlife.
Capelin is managed by a target escapement strategy. MSY for capelin will depend strongly on the cod stock and gives little meaning in a single-species context. There was no fishery for capelin in the area during 2004–2008 due to poor stock condition. During 2009–2013 the stock was sufficiently sound to support a quota between 200 000 and 400 000 metric tonnes. After that, the stock collapsed again, and there was no fishery in 2016, and an agreement of no fishery for 2017. Since 1979, the capelin fishery has been regulated through quotas set using a harvest control rule enforced by the Norwegian-Russian Fishery Commission. The harvest control rule is considered by ICES to be in accordance with the precautionary and ecosystem approaches to fisheries management. Being a forage fish in an ecosystem where two of its predators, cod and haddock, are currently at high levels, the capelin stock is now under heavy predation pressure. The fishery is restricted to the prespawning period (mainly February-March) and the exploitation level is regulated based on a model that incorporates natural mortality, including predation from cod. A minimum landing size of 11 cm has been in force since 1979. The management plan’s harvest control rule is designed to ensure that SSB remains above the proposed Blim of 200 000 metric tonnes (with 95% probability).
For Greenland halibut no limit reference points have been suggested or adopted. The assessment is still considered to be uncertain due to problems with the age-reading and input data quality. The exploratory assessment may nevertheless be accepted as indicative for stock trends. Although many aspects of the assessment remain uncertain, fishery-independent indices of stock size from research surveys indicate positive trends in recent years. After many years of overexploitation of the stock, the recent exploitation rates at F = 0.027 (average over recent 5 or 10 years) have been consistent with a rise in fishable biomass (length ≥45 cm) over the same periods, and hence seems to be sustainable and will not influence the ecosystem negatively (Figure 3.6.14). Reconstruction of historical (pre-1992) stock and exploitation levels is needed to provide a better basis for reference points and evaluation of harvest control rules.
Beaked redfish (Sebastes mentella)
The analytical assessment and advice are provided for ICES Areas 1 and 2 combined. The fishery for S. mentella operates in national and international waters, which are managed under different schemes and by different management organizations. A pelagic fishery for S. mentella developed in the Norwegian Sea outside EEZs since 2004. This fishery is managed by the Northeast Atlantic Fisheries Commission (NEAFC). A new directed demersal and pelagic fishery has been permitted in the Norwegian Economic Zone, since 2014. In 2015 all catches of S. mentella from the Russian and Norwegian fisheries (Figure 188.8.131.52) were taken in the Norwegian Exclusive Economic Zone or as bycatch in the Fisheries Protection Zone around Svalbard, while catches in international waters have mostly been taken by EU countries.
At present, no fishing mortality or biomass reference points are defined for this stock. F0.1 = 0.039 is considered as a good candidate for FMSY proxy when the stock has been re-built. A biomass trigger of 600 kt is a good starting point for management.
The current estimate of fishing mortality is below the assumed natural mortality (0.05) and FMSY proxy (F0.1 = 0.039). Fishing at F0.1, which is close to the assumed value of natural mortality is not considered to be detrimental to the stock, but the historical (1996– 2003) failure in recruitment indicates that catches based on the long-term average FMSY may be inappropriate in the short term.
The Joint Norwegian-Russian Fisheries Commission has not yet decided on a management plan for this stock, nor the elements that should be incorporated in such a future management plan. Until then, ICES only advises on the basis of precautionary considerations that an annual catch in 2015, 2016, and 2017 should be set at no more than 30 000 t (below the catch level corresponding to MSY), and that the measures currently in place to protect juveniles should be maintained. Accordingly, Norway and Russia set a quota of 30 000 t for those years.
Golden redfish (Sebastes norvegicus)
For golden redfish no limit reference points have been suggested or adopted. Golden redfish SSB has been decreasing since the 1990s and is currently at the lowest level in the time-series. Fishing mortality has been increasing since 2005 and is currently at the highest level in the time-series (Figure 184.108.40.206). Recruitment is very low. ICES advises that there should be no fishing on this stock, given the very low SSB (below any possible reference points) and poor recruitment.
Figure 220.127.116.11. Annual fishing mortalities of Golden redfish (Sebastes norvegicus) and Beaked redfish (S. mentella) relative to the target levels (F0.1) as a precautious proxy to FMSY at which the stocks are supposed to give the highest long-term sustainable yields (ICES 2016c).
Experience from other Sebastes stocks, e.g. in the Pacific and in the Irminger Sea, suggests that annual harvest rates of such slow growing and long-lived species should not exceed 5% if the stock is recruiting normally. At a time when this stock is not recruiting normally, even an annual exploitation rate of 5% may be too high. It can thus be concluded that the current fishery of golden redfish is too intensive and may have a negative influence on the stock itself. F0.1 (a typical precautionary proxy for FMSY) is around F0.1 = 0.08. For F0.1 = 0.08 the sustainable yield at current recruitment is 1400 tonnes per year.
Even if the regulations have succeeded in reducing the landings in recent years, if catches are maintained at the current level (3600 tonnes annually) and recruitment is similar to the average recruitment for recent years (2001–2015), the stock size is projected to be very low by 2020.
Polar cod (Boreogadus saida)
For economic reasons, there has been little interest in developing a fishery for polar cod. No fishery at all has been carried in recent years, and the stock size as measured in the Barents Sea in autumn, has also been at very low levels. The historical fishery which has taken place, mainly by Russia, was conducted in late autumn when concentrations of polar cod were targeted during southward spawning migrations along the coast of Novaya Zemlya.
Three species of wolffish: Atlantic wolffish (Anarhichas lupus), Spotted wolffish (Anarhichas minor), and Northern wolffish (Anarhichas denticulatus) are taken mostly as bycatch in fisheries for gadoids in the Barents Sea, but also in a directed longline fishery. From 1905 to 1950, international catches of wolffish in the Barents Sea and along the northern Norwegian coast increased from 100 to 14 000 tonnes. Until 1998 the annual landings were between 6000 and 44 500 tonnes. The high quantity in 1997–2001 was primarily caused by an intensive fishing for northern wolffish because of the bycatch regulations of other valuable species (e.g. Greenland halibut) and a growing Russian market. After 2001, the total wolffish catches north of 62°N decreased, but have improved slightly again in recent years (24 567 tonnes in 2016). The Russian catches increased from a stable level of about 13 000 tonnes in several years, to 18 000 tonnes in the past two years, while Norwegian catches have been about 6000 tonnes in recent years (Figure 18.104.22.168). Northern and Spotted wolffish comprise more than 90% of the total wolffish catch in the Barents Sea region. The Atlantic wolffish are mainly caught in the coastal zone, also outside this region.
Other fish species
Information about the species composition in the Norwegian fisheries north of 67°N is available from the Norwegian Reference fleet (NRF), i.e. 15 high seas and 24 coastal fishing vessels contracted by the Institute of Marine Research. Such data are now routinely being collected from these vessels’ fishery every day or every second day. What affect the fishery may have on all the non-regulated species and the ecosystem will be a subject for further research.
Gullestad et al. (2017) presents the practical implementation of the Ecosystem Approach to Fisheries Management (EAFM) in Norway. This involves defining management objectives and developing simple and efficient tools to achieve an overview of management needs and prioritize among these, while integrating broader conservation issues and ensuring stakeholder involvement.
Species of economic interest not mentioned in this chapter are tusk and ling, and relatively small landings of grenadiers, Atlantic halibut, other flatfish, lumpsucker, hake, pollack, whiting, Norway pout, argentines, salmon, dogfish, skates, and molluscs.