2
P. Tett
the “ecosystem approach”, which is grounded not only in the scientific theory of
ecosystems but also in views about how we might or should try sustain our species’
existence on spaceship Earth. Unlike the planetary-scale problem of global warming, the fish farm–environment interaction is more tractable both to management
and to discussion within the space of this chapter: it largely takes place on space
and time scales that are easy to see. Nevertheless, the general principles are the
same, and if we cannot deal with the impacts of fish-farming – and I think we can
– we are unlikely to be able to deal with the bigger matters.
Because I am writing for regulators, policy makers, human health and nutrition
community, and coastal zone managers, as well as post graduate students in the
field of aquaculture, I include in this chapter some accounts of ecological principles
and attempt to explain them without assuming any prior ecological knowledge. And
so I start by explaining why there are concerns about the environmental impact of
marine aquaculture.
1.2 Humans and Pollution
Once upon a time there was (or may have been) an Edenic age in which small bands
of Eves and Adams and their children wandered through a unspoilt Mediterranean
landscape of small woods and pastures, trapping wild animals and tending wayside
gardens where grew the plants that later became fully domesticated (Mithen 2003).
These small bands stopped for the night or perhaps for a few weeks before moving
on, and, like all humans, they pissed and shat and threw away uneaten bones or
fruit. As human population density, and agricultural skills, increased, the settlements grew larger and less temporary: but never long-lasting, because human
wastes polluted water supplies, and wood cutting and agriculture damaged local
ecosystems. So villages rose and decayed, and populations moved on, or died from
disease and malnourishment, until humans began to learn how to regulate their
waste.
It became possible to live in cities, giving rise to another period of population
increase and environmental pollution. Classical Rome dealt with waste by piping it
down a “cloaca maxima” into the Tiber, where it was flushed out to sea; but elsewhere, Roman mining of metals such as copper and silver created toxic zones
where the soils were rich in heavy metals and streams ran red with acid water. By
the late 19th century most large European cities had recreated Roman sanitation,
and by the late 20th century most European countries were trying to decrease pollution by industrial poisons. But at the same time, the growing populations of these
cities required, and provided markets for, huge quantities of food, which increasingly tended to be produced by semi-industrial methods.
Some of this food came initially from the exploitation of populations of wild
fish: but the supply of this apparently free resource was often unpredictable because
the fish had to be caught far from land and in all weathers, and their imperfect
management led to overfishing. In consequence, aquaculture has grown to provide
P. Tett
the “ecosystem approach”, which is grounded not only in the scientific theory of
ecosystems but also in views about how we might or should try sustain our species’
existence on spaceship Earth. Unlike the planetary-scale problem of global warming, the fish farm–environment interaction is more tractable both to management
and to discussion within the space of this chapter: it largely takes place on space
and time scales that are easy to see. Nevertheless, the general principles are the
same, and if we cannot deal with the impacts of fish-farming – and I think we can
– we are unlikely to be able to deal with the bigger matters.
Because I am writing for regulators, policy makers, human health and nutrition
community, and coastal zone managers, as well as post graduate students in the
field of aquaculture, I include in this chapter some accounts of ecological principles
and attempt to explain them without assuming any prior ecological knowledge. And
so I start by explaining why there are concerns about the environmental impact of
marine aquaculture.
1.2 Humans and Pollution
Once upon a time there was (or may have been) an Edenic age in which small bands
of Eves and Adams and their children wandered through a unspoilt Mediterranean
landscape of small woods and pastures, trapping wild animals and tending wayside
gardens where grew the plants that later became fully domesticated (Mithen 2003).
These small bands stopped for the night or perhaps for a few weeks before moving
on, and, like all humans, they pissed and shat and threw away uneaten bones or
fruit. As human population density, and agricultural skills, increased, the settlements grew larger and less temporary: but never long-lasting, because human
wastes polluted water supplies, and wood cutting and agriculture damaged local
ecosystems. So villages rose and decayed, and populations moved on, or died from
disease and malnourishment, until humans began to learn how to regulate their
waste.
It became possible to live in cities, giving rise to another period of population
increase and environmental pollution. Classical Rome dealt with waste by piping it
down a “cloaca maxima” into the Tiber, where it was flushed out to sea; but elsewhere, Roman mining of metals such as copper and silver created toxic zones
where the soils were rich in heavy metals and streams ran red with acid water. By
the late 19th century most large European cities had recreated Roman sanitation,
and by the late 20th century most European countries were trying to decrease pollution by industrial poisons. But at the same time, the growing populations of these
cities required, and provided markets for, huge quantities of food, which increasingly tended to be produced by semi-industrial methods.
Some of this food came initially from the exploitation of populations of wild
fish: but the supply of this apparently free resource was often unpredictable because
the fish had to be caught far from land and in all weathers, and their imperfect
management led to overfishing. In consequence, aquaculture has grown to provide