The application of the precautionary principle to an area of environme
ntal protection, such as nature conservation, requires commitment to t
he idea that full scientific proof of a causal link between a potentia
lly damaging operation and a long term environmental impact is not req
uired. Adoption of the principle in Government statements related to s
ustainable development should therefore be seen in this context. The p
aper addresses the particular case of marine fish farming in Scotland
where the principle was advocated but not upheld in practice. In the l
ight of this experience there is a need for educators and philosophers
, ethicists and concerned scientists to ensure that the principle is m
ore widely interpreted and understood.