Given the current predictions, 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). However, warmer waters may
provide opportunities to culture new species, or species that are
currently economically marginal in UK waters.
Diseases of cultured fish and shellfish including bacterial,
viral, parasitic and fungal diseases, will be affected by a
changing thermal regime, but in a largely unpredictable manner.
However, under conditions of thermal stress, cultured species are
likely to be more susceptible to disease and warmer conditions may
allow the establishment of exotic diseases, while diseases such as
cold water vibriosisA bacterial disease of migratory and
salt-water fish., 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 treatments. Increased storminess (higher
frequency of strong wind speeds) predicted for certain seasons in
some regions will increase the risk of escapes through equipment
failure and may necessitate site relocation or changes to 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 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. 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.
