Pressures on fish stocks

Fish stocks around North East Scotland remain a mixed picture. Major pelagic stocks such as mackerel and herring still show strong biomass, but risks are rising due to international over-quota catches and climate-driven spatial shifts. Demersal stocks, particularly North Sea cod, remain under significant pressure from environmental change, which limits economic opportunities for fleets operating out of Peterhead and Fraserburgh. Increasing ecosystem variability and management fragmentation mean the NE Scotland fleet faces both biological and political pressures on the long-term stability of its key target species.

Fish stocks in north-east Scotland are increasingly shaped by environmental change in the North Sea, where warming waters, shifting plankton communities, and altered migration patterns are affecting the distribution and productivity of key species. ICES reports that mackerel and herring stocks have shown northward and westward shifts in recent years as sea temperatures rise, contributing to reduced availability in traditional Scottish fishing grounds despite an overall increase in stock biomass at the North Atlantic scale. For demersal species such as cod, haddock and whiting, warming waters have also contributed to lower recruitment and altered spawning behaviour, with ICES identifying persistent “poor” recruitment for North Sea cod since 2015 despite reduced fishing pressure (ICES Advice, 2025). These environmental changes mean that stocks may be biologically healthy at a wider scale but less accessible to the NE Scotland fleet.

While some key pelagic species fished by NE Scotland vessels, such as Northeast Atlantic mackerel, remain within safe biological limits, others continue to face pressure from historical overfishing and slow recovery. ICES notes that North Sea cod continues to be classed as “at risk” despite reductions in total allowable catch (TAC) since 2019. The species has not recovered as expected due to a combination of low recruitment, ecosystem change, and cumulative fishing pressure across EU and UK fleets, requiring repeated quota cuts that directly affect Scottish vessels landing into the NE (ICES Advice, 2025). Whiting and saithe are in comparatively better condition but still managed with precautionary TACs due to recruitment variability. Even for healthier pelagic stocks like mackerel, ICES warns that “fishing mortality has remained above Maximum Sustainable Yield in recent years” because unilateral quota increases by coastal states (UK, EU, Norway, Iceland, Faroe Islands) have pushed the combined catch above scientific advice. This introduces long-term pressure even where stock biomass remains high (UK Government, 2025).

Some stocks in NE Scotland waters experience indirect pressure from bycatch and ecosystem-level impacts. ICES highlights that North Sea cod, whiting and saithe are often caught together in mixed fisheries, making it difficult to manage each species precisely according to its biological limits. The “choke species” effect—where a low quota for one species (e.g., cod) can limit opportunities to fish healthier stocks (e.g., haddock)—can create incentives for discarding or effort shifts that unintentionally increase pressure on vulnerable species. Broader ecosystem pressures, including declining sandeel abundance and reduced zooplankton productivity in the North Sea, also affect the food web supporting pelagic and demersal fish (OAP, 2023).

The UK Marine Strategy (HM Government, 2010, 2019, 2025) strives to achieve Good Environmental Status in UK waters so that commercially exploited fish and shellfish stocks are within safe biological limits (Table 1 and Figure 1) (MOAT, 2024).