Climate change, impacts and vulnerability in Europe ... - MemoFin.fr

Climate impacts on socio-economic systems and health4.3 Fisheries and aquacultureRelevanceIndustries related to the capture of wild fish as wellas marine aquaculture are sensitive to climate change.This section gives an overview of the observed andprojected impacts of climate change on fisheriesand aquaculture. Due to the scarcity of quantitativeinformation, this information is not presented as anindicator.The total fisheries catch of the EU, concentratedmainly in the north-east Atlantic, is the third largestfishery in the world. Commercially relevant wild fishstocks are subject to high levels of exploitation, inmany cases at levels that exceed their reproductivecapacity. In Europe's seas, overfishing is a problem,with 30 % of commercial stocks (those which areassessed) being fished outside safe biological limits.Recently, scientists have also brought attention to thelikely effects of climate change on fish stocks. Stocksare thought to respond to warming conditions bothphysiologically and ecologically. Warming watersare expected to affect fish distribution, migrationpatterns, phenology (timing), food availability(see Section 3.1) and recruitment. In response, thegeographical distribution and productivity of fishstocks could be changing (Simpson et al., 2011). It isfurthermore speculated, that ocean acidification (seeSection 3.1) may eventually impact on the lowestlevels of the food web which ensures availability offood for fish, and hence impact fish productivity. Thehigh levels of fish exploitation, however, mean that itis very difficult to distinguish between changes due tofisheries and those due to ocean warming.Although marine aquaculture depends criticallyon coastal habitats that will be affected by climatechange, it is still very difficult to distinguish betweenpossible climate change effects, natural variabilityin the environment around cages, and technologicalimprovements that generally support thedevelopment of the industry. The industry's concernsare related to changes in the frequency and strengthof storms which may pose a risk to infrastructuresuch as salmon cages and to sea-level rise-inducedchanges in shoreline morphology which may changethe location of habitats suitable for the industry.The emergence, spread and severity of diseases,parasites and pathogens, and the spread of nuisanceand non‐native species could also potentially bedamaging. In Ireland and the United Kingdom,rising temperatures may create the opportunity torear species adapted to warmer water. However,market forces are seen as the more important factorto determine whether existing farmed species will bedisplaced by new ones (Callaway et al., 2012).Past trendsClimate change has had a number of effects in thenorth-eastern Atlantic, where 72 % of commonlyobserved species have responded to warming watersby changing their abundance and/or distribution(see Figure 4.4). Traditionally, exploited fish such ascod have moved further northwards in the region,particularly in the North Sea most likely as a result ofa shift in the thermal regime of the North Sea.Furthermore, warming seas have allowed potentiallynew exploitable stocks to move into some areas.While warming can lead to an increase in fishbiodiversity in a region, there is often a concurrentdecrease in the size structure of the fish population.For example, in the North Sea the relatively smallspecies sprat, anchovy and horse mackerel haveincreased in recent decades, whereas the largerspecies cod and plaice have decreased at theirsouthern distribution limit (Perry, 2005). This changemay have important socio‐economic consequences asthe stocks moving out of the North Sea tend to have ahigher value than the stocks moving into it.As catch of wild fish species has been decreasingwhile the demand for fish and fish products hasincreased, a large increase in the total EuropeanKey messages: 4.3 Fisheries and aquaculture• The effects of climate change, in particular of ocean warming, on wild fish distributions and aquacultureare difficult to distinguish from those of high exploitation rates or technological developments.• Wild fish stocks seem to be responding to changing temperatures and food supply by changing theirgeographical distribution.• Future climate change is likely to lead to an increased catch potential in the Arctic, and to a decreasedor constant catch potential in other European seas.• Climate change can influence where aquaculture is possible, which species are raised, and the efficiencyof the production.Climate change, impacts and vulnerability in Europe 2012181