Review of climate change impacts on marine fish and shellfish around the UK and Ireland

Abstract

ABSTRACT1. Recent and projected future changes in the temperature and chemistry of marine waters around the UK and Ireland are having, and will in the future have, effects on the phenology, productivity and distribution of marine fish and shellfish. However, the overall consequences are still hard to predict because behaviour, genetic adaptation, habitat dependency and the impacts of fishing on species, result in complex species' responses that may be only partially explained by simple climate envelope predictions.2. There is a broad body of evidence that climatic fluctuations are playing an important role in changing fish distributions and abundances, which is discernible against the background of trends in abundance due to fishing. During warm periods, southern species have tended to become more prominent and northern species less abundant. However, the changes in distribution are often more complicated than might be expected from a simple climate envelope approach, partly due to ocean circulation patterns which create invasion routes for southern water species into the North Sea from the south and from the north via the continental shelf west of Britain and Ireland.3. The eventual population-scale impacts of ocean acidification on fish and shellfish are currently very difficult to predict. However, the scant evidence suggests that indirect food web effects arising from the enhanced sensitivity of calcifying planktonic organisms may be important, and the direct effect on fish sensory systems leading to subtle influences on behaviour with possible population-level implications are possible.4. In British waters, the lesser sandeel (Ammodytes marinus) is identified as being at particular risk from climate change. Owing to its strict association with coarse sandy sediments it is unable to adapt its distribution to compensate for warming sea temperatures. Sandeels are a key link in the food web, linking primary and zooplankton production to top predators.

Impacts of Climate Variability on Latin American Small-scale Fisheries

“…Owing to their strict association with sedimentological variables (Defeo and McLachlan 2011), several shellfishes are unable to adapt their distribution to compensate for warming temperatures and other climate change consequences, such as ocean acidification and sea level rise (Defeo et al 2009, Heath et al 2012, Narita et al 2012. These drivers could affect habitats and biophysical processes and thus could alter shellfish demography, dispersal patterns, life history traits, and interaction strength with other species (Stenseth et al 2002, Rouyer et al 2008, Mellin et al 2012.…”

Environmental Impacts—Marine Ecosystems

“…Species with northward-shifting distributions had faster life cycles and smaller body sizes than non-shifting species (Perry et al 2005). The shifts in latitude or into deeper water were correlated with variations in temperature estimated from measurements carried out during the same surveys and implied that shifting species remained within a constant temperature range (Beare et al 2004;Heath et al 2012). The landings distributions of cod, saithe Pollachius virens, haddock, European hake Merluccius merluccius, and European seabass all showed northward shifts of 25-50 km decade…”

“…Fish production in the North Sea is more strongly coupled to zooplankton production than is the case in the Celtic Sea and so it is likely that the effects of climate on North Sea fish are primarily via trophic links to the lower end of the food chain (Heath 2005). In this context the effects of climate change on lesser sandeel Ammodytes marinus may be particularly critical, since it is a non-migratory species that is very dependent on the availability of coarse sandy substrate (Heath et al 2012). …”

“…Poulsen et al 2007), archaeology (Enghoff et al 2007) and other sources. The wealth of sampling and scientific analysis that exists for the North Sea shows the need to look deeper than simple, direct effects and linear responses to one or two variables and to be wary of general conclusions from incomplete models (Heath et al 2012). It is salutary to find that even in a very well-studied species such as cod in the North Sea, the causes of changes in distribution, abundance and population structure over the past century are still not fully understood, but are undoubtedly complex.…”

Sustained Observation of Marine Biodiversity and Ecosystems

“…There is however, the potential for new fisheries to develop when warm-water species expand pole-wards [41,42]. Low biomass stocks that have been fished down can be less resilient to climate change.…”