Human activities and their pressures
- Fishing continues to be the main threat to ecosystem health. This is despite a decrease in fishing pressure in recent decades as can be observed from two of its main pressures, i.e. species extraction and physical seabed disturbance. A further reduction in fishing pressure is likely to improve the status of the majority of the ecosystem components.
- Shipping is responsible for the majority (53%) of the introductions of non-indigenous-species, mainly through ballast water and hull fouling, and has clearly increased over the past two decades. Aquaculture is the next important activity, responsible for a further 18% of introductions. Effects of this pressure may include: the out-competing native species, the fouling of aquaculture and fishing gear, and fish kills through toxin production.
- Energy production activities such as oil and gas extraction industries are still among the main activities impacting the ecosystem through pressures like contaminants and physical habitat loss. Pressures from oil and gas industries are expected to decrease, while pressures caused by offshore windfarms are expected to increase with the ongoing energy transition.
State of the ecosystem
- Fishing-induced physical disturbance is estimated to have resulted in an overall decrease of invertebrate benthic biomass of approximately 20% in the ecoregion compared to an unfished state. This impact is patchy and may be as high as 90% in the most heavily fished areas.
- The stock sizes of most groups of commercial species are now overall above levels that can provide the maximum sustainable yield (MSY); however, some individual species within these groups may still be below MSY levels.
- Seabird abundance appears to be declining; reasons for this may include changes in migration patterns as well as reductions in breeding success and lower survival.
- The numbers of two main seal species in the ecoregion – grey seal (Halichoerus grypus) and harbour seal (Phoca vitulina) – have increased from an all-time low in the 1970s, with large population changes over the past decades caused by two major outbreaks of the phocine distemper virus. Trends in the abundance of cetaceans are less known.
Climate change
- Climate change is causing warming of surface water temperature. This has already changed spatial distribution of several plankton and fish species within the ecoregion and is likely to continue. Further cascading effects are likely to occur throughout the ecosystem with consequences on the spatial distribution of fisheries. Marine spatial planning should therefore consider this when planning infrastructure such as wind farms or implementing marine protected areas.
Environmental and socio-economic context
- Eutrophication was impacting the ecoregion in previous decades, peaking in the 1980s; however, the introduction of measures to reduce riverine input of nutrients since then has reduced this pressure to the point of no major concern.
- The current trend of increased fuel prices and resulting decrease of fishing with bottom‑towed gears is likely to result in a further reduction of the extraction of demersal fish and disturbance of seabed habitats. If this also results in a shift toward less fuel‑intensive fisheries, such as gillnets, than this is likely to result in increased bycatch risk of seabirds and marine mammals including longer-term effects from lost and abandoned fishing gear.
- In targeting specific fisheries with additional management interventions it is worth considering that small-scale coastal fisheries contribute 10% of value landed but have regional importance in terms of employment (18% FTE) and revenue (11%).
