Introduction of Alien Species
More than 250 marine species have been
introduced into Australian waters from around
the world. Many of these species remain
inconspicuous, but a few have established large
populations and become pests. It is estimated
that one in each six to 10 introduced marine
species will become a pest.
Pests are defined as species that are likely to
have a major impact in a new environment
on economy, environment, human health or
amenity. Species that have been invasive
elsewhere are often considered a high risk
of becoming pests in Australia.
Alien species can be introduce into Australian waters in many ways:
The growth of marine organisms on artificial
surfaces, including vessels’ hulls and internal
spaces, is called ‘fouling’.
Ballast water - Modern steel ships now carry water rather than rocks as ballast. Every day, it is estimated that around 7,000 different marine species including viruses, bacteria, and small marine invertebrates, are transported around the world in ballast water.
Unintentional release from public or
Deliberate Introduction for aquaculture, e.g. , in 1947, the Pacific oyster Crassostrea
gigas was imported into Tasmania and Western
Australia for aquaculture. It was later introduced
deliberately into Victoria and South Australia.
The Pacific oyster is a highly invasive species and
competes for space occupied by native oysters.
It has spread into New South Wales where it is
listed as a noxious species in all state waters
except Port Stephens (where it is cultured). In
Tasmania, the Pacific oyster is cultured and is not
considered a pest.
A National Taskforce has established guidelines
to ensure that fish and fish products imported
for aquaculture are not likely to present a risk
to coastal environments.AQIS also assesses the
risk of importing live aquaculture and
In order to rapidly and cost-effectively develop and diversify aquaculture interests, commercial enterprises in several countries have turned to pre-existing aquaculture species from other regions, such as the Japanese Oyster, Crassostrea gigas, the Atlantic Salmon, Salmo salar, and the California abalone, Haliotis rufescens.
By using these species, research and development costs are minimised through use of overseas research and development outputs. Similarly, these new enterprises can utilise pre-existing markets with well established brand identity to create a more rapid profit. This use of potentially invasive Alien Species in new and different locations and with farming practices that rarely provide a zero-risk of accidental release is problematic from biodiversity protection and transboundary perspectives.
A number of international, regional and national instruments exist to manage alien species use in aquaculture systems; however an analysis of the gaps in ese systems and the extent to which they are applied has yet to be undertaken. As the demand for novel aquaculture production increases, government authorities will increasingly have a key role to play in enhancing effective collaboration with and among many players, in order to promote sustainable development of aquaculture.
Responsibilities for sustainable aquaculture development will need to be shared among government authorities, aquafarmers, manufacturers and suppliers of aquaculture inputs, processors and traders of aquaculture products, financing institutions, researchers, special interest groups, professional associations, non-governmental
organizations, and others.