IMPACTS OF CLIMATE CHANGE ON AQUACULTURE
Matt Gubbins
Fisheries Research Services, Victoria Road, Aberdeen
Executive Summary
The dominant species currently produced by marine aquaculture (mariculture) in Scotland are Atlantic salmon, mussels and oysters. To date, there has been little published research or consensus opinion on the effects of climate change on Scottish mariculture. However, much can be inferred from the published literature on the effects of environmental variables on cultured species.
Given the current predictions (Reddin et al., 2006), climate change is unlikely to have a significant effect on Scottish mariculture over the next decade. However, within the next 50 years or more, the forecast changes are likely to result in noticeable effects. Rising average water temperatures will result in faster growth rates for some species (e.g. Atlantic salmon, mussels and oysters) but prolonged periods of warmer summer temperatures may cause thermal stress, particularly for cold water species (e.g. cod and Atlantic halibut) and intertidal shellfish (oysters), possibly preventing their culture at some sites, causing welfare problems and necessitating temperature control for broodstock of some species (Cano and Nicieza 2006). However, warmer waters may provide opportunities to culture new species, or species that are currently economically marginal in Scotland (Tackle et al., 2006).
Diseases of cultured fish and shellfish (Goniea et al., 2006), including bacterial (Galbreath et al., 2006), viral (Larsson and Berglund 2006), parasitic (Levesque et al., 2005) and fungal (Claireaux et al., 1995) diseases, will be affected by a changing thermal regime, but in a largely unpredictable manner, due to the uncertainties in the temperature induced variations in the immune response of the cultured species. However, under conditions of thermal stress, cultured species are likely to be more susceptible to disease. Warmer conditions may also allow the establishment of exotic diseases, whereas diseases that occur under cool conditions, e.g. cold water vibriosis, may become much rarer. Sea lice are likely to remain a problem in salmon culture and rising temperatures will extend their season and may increase infective pressure, requiring more clinical interventions (Levesque et al., 2005). Increased storminess (higher frequency of strong wind speeds) (Hurst et al., 2005) predicted for certain seasons in some regions will increase the risk of escapes through equipment failure and may require relocation of some sites or changes in equipment design.
The forecast warmer waters with calmer, drier summer months will have an effect on planktonic communities, although this will be difficult to predict in detail. There may be an increase in the frequency of harmful algal (Imsland et al., 2000) and jellyfish blooms, potentially causing more fish kills and closures of shellfish harvesting areas, but the forecast reduction in summer precipitation may benefit classification of shellfish growing areas (Aune et al., 1997). Increased temperatures and more abundant plankton could also enhance early spawning success and spat fall of cultured shellfish species, to the benefit of the shellfish industry.
Level of Confidence
See supporting evidence (explanatory notes for each subject have individually assigned confidence levels)
Key sources of Information
Please acknowledge this document as: Gubbins, M (2006). Impacts of Climate Change on Aquaculture in Marine Climate Change Impacts Annual Report Card 2006 (Eds. Buckley, P.J, Dye, S.R. and Baxter, J.M), Online Summary Reports, MCCIP, Lowestoft, www.mccip.org.uk