- In the UK, there have been no major changes to the types or locations of species farmed due to climate change.
- At salmon farms, a strong link between milder winter temperatures, disease and increased fish mortality has been identified, and marine heatwaves can contribute to mass mortality events.
- In Scotland, some shellfish areas have experienced poor spat settlement and mortality, but the link to climate change is not fully established.
Moderate evidence, low consensus
There have been no major shifts in species farmed or evidence for climate-driven changes in production. Any climate effects are low compared to changes associated with economic and technological developments in the industry. There is some evidence for temperature-related effects on salmon mortality, emergence of amoebic gill disease, Harmful Algal Blooms, jellyfish, invasive species, and shellfish infections, although there are no trends for storm damage.
Overall confidence remains ‘low’ (evidence and consensus) as only a few factors link directly to climate change, as opposed to seasonality. However, the evidence has increased since Murray et al. (2022) leading to an increase from low to moderate for this axis.
- Temperatures are expected to remain suitable for salmon growth until the end of the century, when aquaculture in Northern Ireland and the southwest of Scotland may experience seasonal declines due to warming.
- Ocean acidification may reduce shellfish spat settlement, although it is unlikely to affect finfish farming.
- Warming conditions will lead to a rise in outbreaks including sea lice, fish diseases and shellfish pathogens, with subsequent increased mortality.
- The risk of mortality due to more frequent and intense heatwave events will increase in the future, highlighting the need for adaptive management.
- Facilities in sheltered coastal areas may experience more fluctuation in temperatures, salinity and OA, but be less exposed to structural damage due to potential changes in storm events, creating different challenges for farming in different areas.
Medium evidence, low consensus
Salmon growth rates are likely to increase but UK waters are expected to remain suboptimal for new species such as sea bass. Existing impacts from gill disease, and effects of sea lice are likely to continue. Similarly, shellfish aquaculture may benefit from increased growth rates in warmer waters, although diseases may become more prevalent and ocean acidification may reduce mussel smolt settlement. New species of shellfish such as abalone might be farmed in southern UK waters. Future impacts from HABs and jellyfish could increase in warmer seas but there is low confidence as blooms depend on complex ecosystem behaviour.
Seaweed aquaculture has considerable potential to expand, but this potential might be reduced under a warming climate. There is a need for more research on increasing resilience of seaweed in response to climate change, with an eye on future cultivation.
Overall, there is moderate confidence in impacts from climate change. Disease impacts will be negative, but some negative impacts may be mitigated by adaptation strategies and technological fixes, particularly in the salmon sector which has a high level of innovation, and growth rates are likely to increase. So net impacts of climate change may be low.
- Understanding synergies between different pathogens and environmental drivers in fish health response to climate change, such as complex gill disorder (CGD).
- Understanding the synergistic effects of climate change and ocean acidification (and the effect of fluctuating, compared to continuous, exposure to these impacts) on settlement, growth and shellfish aquaculture species.
- Identifying the potential impacts of climate change on environmental conditions at aquaculture sites, such as the assimilative capacity of receiving water bodies, including those offshore.
- Identifying climate change impacts favour the establishment and spread of invasive non-native species and their potential impacts on the sector.
Image credit: Joshua Gray, Crown Copyright