Aliens and Risk Assessment
The risks posed by aliens are a hot
topic for consideration in many international meetings.
The Convention on Biodiversity (signed by over 170 governments),
for instance, will have a special work program starting
this summer. But a lot of time will not be spent discussing
invaders from Mars but the movement of species (animals,
plants, bacteria, viruses etc.) around the world to places
where they would not occur naturally. As an industry we
possibly move more individuals of more species around the
world than any other. Thus potentially we may face greater
scrutiny than our economic size would otherwise dictate.
Aliens are any species that
is moved out of their natural range. When this happens there
are a number of possible outcomes.
- The individuals transferred just die.
This could be because of a number of reasons for instance
the habitat may be entirely unsuitable or the number of
specimens introduced are insufficient to create a successful
breeding colony.
- The species may colonise the area to
which it has been introduced but not spread any further.
- The species thrives and rapidly colonises
a wide area. It is then termed an invasive species. Examples
of invasive aliens include the zebra mussel in North America,
the common carp in Australia, koi in New Zealand and the
seaweed Caleurpa sps. in the Mediterranean.
Of most concern are the invasive
species. However predicting with absolute certainty species
which will become invasive is very difficult.
Much time is now
being spent by agencies in "Risk Analysis". That is trying
estimate the risk of an animal, plant, bacteria or virus causing
problems in areas to which it might be introduced.
It must be said at the outset
that the only way to ensure "no-risk" is ban the movement
of all materials. This would be impossible since materials
move around the world in the oddest of places e.g. ballast
water in ships, frogs in consignments of bananas, beetles
in the bark on timber, monkeys in the landing gear of planes
(that's not a joke), and substantial trade would be brought
to a halt.
Governments generally do
not operate a "no-risk" policy but adopt policies which limit
the practical risks associated with the movement of biological
material. A risk assessment cannot determine whether a risk
is acceptable just how great it is. Ultimately a political
decision on what level of risk is acceptable must be made
by elected governments - in line (hopefully) with internationally
recognised standards.
The risk of particular movements
will vary depending on many factors. Thus in the case of fish,
the chances of most tropical fish (and any associated pathogens)
becoming established in the wild in temperate north America
or Europe are virtually zero. Even if they survive in the
summer they couldn't survive the winter.
Since "risk analyses" will
be, or already are being undertaken, on the industry further
details of how and in what contexts they will be applied to
the industry will covered in later Newsletters.
