Adaptation Actions for a Changing Arctic: Perspectives from the Barents Area

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Chapter 6 · Impact analysis and consequences of change

ecosystem to future climate change and ocean acidification (Section 6.2.2.1). Non-climatic impacts can be physical (e.g. construction, dredging), chemical (e.g. direct waste discharges, oil spills) or biological (e.g. invasions of non- indigenous species, reef effect around platforms and pipelines). The greatest human impact on the Barents Sea fish stocks, and thus on the functioning of the ecosystem as a whole is from commercial fisheries. Fishing occurs in most of the Barents Sea except the far north. Declining sea ice is opening new grounds for trawling and for transport routes, with potential for impacts (see also Section 6.3.1.4; ICES, 2016). The influence of land-based industrial activities and river outflow within the Barents area are greatest in the coastal zone. Coastal areas of Russia in the Barents Sea are sub-divided into 16 impact zones and ‘hot spots’ with elevated levels of environmental risk due to river runoff, air pollution and economic activities in the coastal zone (Evseev et al., 2000). There is extensive international cooperation on protecting the marine environment and managing maritime activity, including maritime transport, and the use of living resources and petroleum resources. The management regimes, technologies and standards are constantly being developed, to ensure integrated, ecosystem-based management, reduced pollution risk and protection of biodiversity. Overfishing (i.e. removal of commercial species above allowable limits) results not only in unstable fish populations and a corresponding fall in catches, but also in a change in trophic structure at the sub-regional and regional level. Under the current ecosystem-based management regime most commercial stocks are in good shape and fished sustainably, although there are some examples of overfishing from the past in the Barents and Norwegian Seas (Matishov, 2007; WWF, 2007; McBride et al., 2014). Despite national and international regulations, the discard of non-target species is widespread in many marine areas and can account for as much as 20–80% of the total catch. It is estimated that discard of the main commercial species in the Barents Sea can represent 10–30% of catches (UNEP, 2004; WWF, 2005). Discards may lead to local organic pollution and can affect the natural balance of the marine food web. Concern also extends to non-commercial and protected species, when bycatch endangers those with vulnerable life histories and protected species at low population levels. Even low levels of bycatch mortality may pose a threat to Red List species such as common guillemot ( Uria aalge ), white-billed diver ( Gavia adamsii ), and Steller’s eider ( Polysticta stelleri ).There is particular concern about the skates of the Arctic and northern European seas, as their abundance has declined dramatically through incidental by-catch over the past 100 years (Kaiser and de Groot, 2000). The destructive impact of bottom trawling operations on benthic habitats and communities is a particular concern (see Figure 6.6). In areas of traditional trawl fishing, including the Barents Sea, such operations can cover up to half the sea area and can result in the death of 20–40% of benthic organisms. Trawling impacts are greatest on hard bottom habitat dominated by large sessile fauna (Jørgensen et al.,

Figure 6.6 Impact of bottom trawling on the benthic community in the Barents Sea: before trawling (upper) and after trawling (lower) (photos Mareano/Institute of Marine Research, Norway).

2015). Direct visual observations in the Barents Sea show vast areas of the seabed exhibit traces of trawling in the form of a trench 2.3 m wide and 0.8 m deep, where the benthic fauna has been virtually eliminated (Aibulatov, 2005). The most vulnerable species include corals, sponges and other components of benthic communities. Such species can take tens to hundreds of years to recover from trawling pressure. The long-term impacts of bottom trawling are now the focus of detailed studies in relation to the development of ‘sustainable fisheries’ (Lyubin et al., 2011; WWF, 2013). Aquaculture is increasing along the coasts and in the fjords of northern Norway and Russia, with several commercial fish farms producing salmonids (salmon Salmo salar , trout Oncorhynchus mykiss ) and shellfish. Red king crabs ( Paralithodes camtschaticus ) were released in the past to provide a resource for fishing, but these releases are now regarded as the introduction of an invasive species and the long-term effects on the ecosystem are unknown (ICES, 2016). Oil and gas activities affect large areas of the sea, the seabed and land (see Figure 6.7).They affect the environment through emissions to air, noise from seismic surveys, and their physical footprint on the seabed. Further development of oil and gas activity will depend on market prices and climate policy, where reductions in oil and gas activity may play a major role in countries’ mitigation commitments (see Sections 6.3.3.1 and 6.3.3.2 and Box 6.3). The biological effects of impulsive noise from seismic surveys on fish and other marine organisms may vary widely – from effects on the orientation and food searching systems (eyesight, hearing,olfaction) to physical damage of organs and tissues,and ultimately death.Zooplankton and fish at early life stages (larvae, fry, and possibly eggs) are particularly vulnerable. Mortality in