Ecosystem overviews

Greater North Sea Ecoregion

Pressure: Selective extraction of species

The main contributing activity to selective extraction of species in the Greater North Sea is commercial fisheries, which peaked at 4 million tonnes in the 1970s but have since declined to about 2 million tonnes. In addition, recreational fisheries can be expected to significantly contribute to the pressure for at least some species. There has been a significant decline in the overall fishing effort in the ecoregion resulting in lower catches of both commercial (Figure 3) and non‑target species. The categories of landings of commercial species can be assumed to represent to some degree the magnitude of the pressure on different non-target ecosystem components. For example pelagics represent the risk from the pressure on marine mammals, while the demersal and specifically the benthic categories are indicative of the risk to the benthic habitats and associated biota. There have been shifts in fishing techniques towards gear types that require less fuel (e.g. pulse trawl, sum-wing, twin-rigging, and flyshooting) but also differ in terms of their catchabilities of both commercial species and bycatch of non-target species. Sustainable fisheries management aims to minimize long-term negative effects on ecosystem components (notably the commercial species) while seeking long-term economic and social viability of the fisheries. The impact of the EU/UK landing obligation on fishing behaviour, data gathering, and stock assessments remains under review.

Effects on commercial stocks

Most North Sea fish stocks for which ICES undertakes an assessment are now fished at rates at or below FMSY. Average fishing mortality (F) for shellfish (Norway lobster), demersal, and pelagic fish stocks has been reduced since the late 1990s (Figure 4). Even if the average fishing mortality is at or below MSY, there may still be several stocks with fishing mortality rates above FMSY such as cod (Gadus morhua), saithe (Pollachius virens), mackerel (Scomber scombrus), blue whiting (Micromesistius poutassou), and sole (Solea solea) in the English Channel, as well as some Norway lobster stocks. There are also fisheries on forage fish in the North Sea such as sandeel (Ammodytidae), sprat (Sprattus sprattus), Norway pout (Trisopterus esmarkii), and herring (Clupea harengus). These are primarily for fish meal and oil (except for herring, where most of the catch is for human consumption). Notably, the demersal fisheries in the ecoregion take bycatches of other commercial species even when targeting a particular species. Detailed information on fisheries is provided in ICES Greater North Sea ecoregion Fisheries Overview.

European eel migrates throughout the Greater North Sea ecoregion as a larval recruit and maturing adult, and its status remains critical. ICES has advised in 2022 that there should be zero eel catches of in all habitats. This includes catches in both recreational and commercial fisheries and catches of glass eels for restocking and aquaculture. In addition, all non-fisheries related anthropogenic mortalities of eel should be zero, and the quantity and quality of eel habitats should be restored.

Effects on non-target species

Fishing is known to extract many other species not specifically targeted including those of fish, cephalopods, benthic invertebrates, seabirds and marine mammals. Incidental bycatches of protected, endangered, and threatened species (PETS) occur in several North Sea fisheries. A list is available for the ecoregion of species of bycatch relevance (fish, marine mammals and seabirds; annexes 1 and 2 in ICES [2022c]). The fish species are mainly bycatch in demersal fisheries and may include several elasmobranchs such as spurdog (Squallus acanthias), the common skate complex (Dipturus spp.), angel shark (Squatina squatina), porbeagle (Lamna nasus), and some deep-water sharks. In 2021, most of the fish records were for tub gurnard (Chelidonichthys lucerna) in bottom trawls.

Bycatch in fisheries is probably the human activity that has the greatest effect on the population abundance of marine mammals in the ecoregion. The highest multiannual bycatch rates during 2017–2021 were recorded for common dolphin (Delphinus delphis) in purse seines and harbour porpoise (Phocoena phocoena) in set gillnets. Bycatch of seabirds in the ecoregion occurs but is not believed to be a large pressure on seabird populations. The highest seabird multiannual bycatch rate during 2017–2021 was recorded for northern fulmar (Fulmarus glacialis) in set longlines. For further bycatch information see the Greater North Sea ecoregion Fisheries Overview.

Discarding by commercial fisheries

Discarding as a fisheries-related practice linked to the extraction of species, is predominantly associated with other pressures such as 'Nutrient and organic enrichment' and 'physical seabed disturbance' (through smothering), potentially affecting several ecosystem components (e.g. known to attract seabirds) and foodweb functioning. In 2016–2020, discard rates were highest in the demersal (10–20%) and benthic (20–30%) fisheries, while discard rates of pelagic species were close to zero.

Recreational fishing

Recreational fishing is an increasingly important activity in parts of the ecoregion, with a diverse range of species exploited from a variety of platforms (e.g. shore and boat) using many gears (e.g. rod and line, speargun, nets, pots, and traps), along with hand collecting/harvesting from the shoreline. The relative contribution of recreational fishing is increasing as a proportion of the total catch of specific species in certain locations. Recreational fisheries in the ecoregion target a wide range of species, but few of these fisheries are monitored or evaluated. Recreational catches of sea bass (Dicentrarchus labrax) and salmon (Salmo salar; including freshwater catches) are significant and are included in ICES assessments of these species. A comparison of the recreational catches to the commercial catches of sea bass in the ecoregion and beyond (i.e. ICES divisions 4.b–c, 7.a, and 7.d–h) based on information from the main countries, estimates that the total retained catches by recreational fisheries of 2192 tonnes exceed those by the commercial fleet (1869 tonnes).