8 Externalities in Aquaculture
255
economic significance for aquaculture it seems appropriate to start our discussion
with these.
8.3.1 Impacts on Aquaculture of External Events
Some external events can be classed as either totally or partially anthropogenic
(e.g., acute or chronic pollution, ‘red tides’ linked with eutrophication), while others
are caused by natural hazards (e.g., storms). Our concern is mainly with the former,
since these correspond most closely with the definition of externalities given earlier; that is, unintended side effects of human activity which have an economic
impact on third parties. However, experience suggests that natural hazards may be
just as financially ruinous to individual fish farmers as those that are anthropogenic,
and within the DPSIR framework it seems sensible to consider both types of event.
The focus of discussion in this section is on specific examples of environmental
disturbance where a direct connection can be made with the operating performance
of fish farms. Changes which might impact indirectly on aquaculture, such as global warming, are not considered though their potential importance is recognised.
Pollution incidents have impacted on aquaculture in a number of documented
cases. The Amoco Cadiz oil spill tanker disaster in 1978 caused serious losses to
the Brittany oyster farming industry, estimated at 107 million FF (= US $26 million)
at 1978 equivalent values (Grigalunas et al. 1986), while the more recent Prestige
incident in 2002/3 is reckoned to have led to a drop in the annual production value
of Galician aquaculture (mussels and turbot) of approximately 9 million euros
(Garza-Gil et al. 2006). As well as acute pollution incidents such as oil spills,
chronic pollution has also been shown to be damaging to aquaculture. This is well
illustrated by the effects of organotins on shellfish, a particularly noteworthy case
being the culture of oyster (Crassostrea gigas) in Arcachon Bay (France) where
reproductive failure and shell deformation caused by the presence of TBT resulted
in very heavy financial losses by the shellfish industry in the early 1980s (Santillo
et al. 2001). Environmental disturbances not directly linked with pollution have also
been shown to have serious consequences for aquaculture, in some cases with wider
implications for society at large. In the US, harmful algal blooms (HABs) are estimated to have caused losses to commercial fisheries (capture and culture) of
between $14 m. and $26 m. annually for the period 1987–1992 (Anderson et al.
2000), with some notably severe incidents affecting farmed salmon in the state of
Washington. In one year alone, HABs led to massive kills of net pen salmon in
northern Puget Sound and caused losses in production value of approximately
$11 m. In the UK, the infectious salmon anaemia (ISA) virus was estimated to have
caused a drop in turnover for Scottish salmon growers in the late 1990s of some
14%, due to a combination of enforced slaughter of stock and depressed prices
(Scottish Parliament Information Centre 1999). Jobs in the industry were lost
directly as a result, with knock-on effects for employment in related sectors
upstream and downstream.
255
economic significance for aquaculture it seems appropriate to start our discussion
with these.
8.3.1 Impacts on Aquaculture of External Events
Some external events can be classed as either totally or partially anthropogenic
(e.g., acute or chronic pollution, ‘red tides’ linked with eutrophication), while others
are caused by natural hazards (e.g., storms). Our concern is mainly with the former,
since these correspond most closely with the definition of externalities given earlier; that is, unintended side effects of human activity which have an economic
impact on third parties. However, experience suggests that natural hazards may be
just as financially ruinous to individual fish farmers as those that are anthropogenic,
and within the DPSIR framework it seems sensible to consider both types of event.
The focus of discussion in this section is on specific examples of environmental
disturbance where a direct connection can be made with the operating performance
of fish farms. Changes which might impact indirectly on aquaculture, such as global warming, are not considered though their potential importance is recognised.
Pollution incidents have impacted on aquaculture in a number of documented
cases. The Amoco Cadiz oil spill tanker disaster in 1978 caused serious losses to
the Brittany oyster farming industry, estimated at 107 million FF (= US $26 million)
at 1978 equivalent values (Grigalunas et al. 1986), while the more recent Prestige
incident in 2002/3 is reckoned to have led to a drop in the annual production value
of Galician aquaculture (mussels and turbot) of approximately 9 million euros
(Garza-Gil et al. 2006). As well as acute pollution incidents such as oil spills,
chronic pollution has also been shown to be damaging to aquaculture. This is well
illustrated by the effects of organotins on shellfish, a particularly noteworthy case
being the culture of oyster (Crassostrea gigas) in Arcachon Bay (France) where
reproductive failure and shell deformation caused by the presence of TBT resulted
in very heavy financial losses by the shellfish industry in the early 1980s (Santillo
et al. 2001). Environmental disturbances not directly linked with pollution have also
been shown to have serious consequences for aquaculture, in some cases with wider
implications for society at large. In the US, harmful algal blooms (HABs) are estimated to have caused losses to commercial fisheries (capture and culture) of
between $14 m. and $26 m. annually for the period 1987–1992 (Anderson et al.
2000), with some notably severe incidents affecting farmed salmon in the state of
Washington. In one year alone, HABs led to massive kills of net pen salmon in
northern Puget Sound and caused losses in production value of approximately
$11 m. In the UK, the infectious salmon anaemia (ISA) virus was estimated to have
caused a drop in turnover for Scottish salmon growers in the late 1990s of some
14%, due to a combination of enforced slaughter of stock and depressed prices
(Scottish Parliament Information Centre 1999). Jobs in the industry were lost
directly as a result, with knock-on effects for employment in related sectors
upstream and downstream.