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Fish
What is already happening?
  • There have been substantial changes in fish communities in UK waters, linked to the appearance of warm-water species (e.g. European anchovy) and local declines of some cold-water species (e.g. eelpout).
     
  • Warming temperatures have affected the timing of spawning among species. For example, warming has led to earlier spawning for sole, but for Raitt’s sandeel, warming delays reproductive development.
     
  • Warming and associated oxygen solubility appears to be affecting the age at maturation, growth rates, and the maximum size fish can attain.
     
CONFIDENCE LEVEL
MEDIUM

High evidence, medium agreement

There is generally high agreement on changes in composition and size of fish communities (increase in warm water species and a decrease in habitat for many cold-water species). There is less evidence for links between fish larvae and their prey, mean size and temperature and effects of ocean acidification, and observational record gaps for smaller plankton prey.

What could happen in the future?
  • By 2050, climate-driven changes in suitable available habitat could become a major constraint on some commercial species’ distributions in the North Sea.
     
  • Experiments suggest that Atlantic cod larvae may experience higher mortality rates due to ocean acidification compared with European seabass and herring larvae. 
     
CONFIDENCE LEVEL
MEDIUM

Medium evidence, medium agreement

There is substantial effort being made to combine and develop various modelling approaches to predict future distributions and abundances of fish species, including predicting species that may invade suitable habitat in future conditions. However, evidence for future change is low to medium as most insights come from modelling rather than empirical studies.

Key Challenges and Emerging Issues
  • Assessing the vulnerability of fisheries to changing storminess to direct adaptation.
     
  • Developing more robust projections of climate change impacts on productivity and distribution at a species level, through better integration of data on life trait characteristics.
     
  • Distinguishing the contribution of climate drivers to changes in fish distribution, productivity and size from other drivers.
     
  • Improving parameterisation of models through more validation and empirical studies, including habitat dependency, physiology and individual and population dynamics.