| Summary: | Marine climate change is having an impact on individual species and fish communities at local and global scales. Under continuing climate change, marine species and communities are predicted to change their distribution to follow preferred thermal conditions. However, availability of suitable habitats and depths will limit opportunities for many species, especially those with physiological and ecological dependence on benthic habitats and demersal communities. This thesis begins in Chapter 1 by exploring existing research recording how climate change has affected marine species, especially those in the Northeast Atlantic, followed by a summary of how future marine warming is predicted to change species distributions, abundances and associated harvesting opportunities. In Chapter 2, the influence of relatively fine-scale environmental variation on European plaice (Pleuronectes platessa) growth in the North Sea is analysed. Detailed analysis of spatially segregated plaice sub-groups shows that accepted growth responses to temperature variation are not always seen in heavily exploited fish that don’t reach their full age and size potential. Chapter 3 presents current, and predicts future, distribution of key commercial fish species in the North Sea. Standardised survey data are used to develop, test and predict species abundances using generalised additive models (GAMs) coupled with climate projections to 2050. The models predict that future distributions of demersal (bottom-dwelling) fish will be strongly constrained by availability of preferred habitat at suitable depth, unless species are able to acclimate or adapt to tolerate warmer conditions or move to previously uninhabitable locations. Chapter 4 presents analysis on a newly compiled fisheries survey dataset, spanning from the southern end of Spain to the northern coast of Norway, and standardises the data using least square mean estimates of abundance. Principal coordinate analysis suggests that surface temperature is the main driver of fish assemblages, ...
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