Managing biodiversity in aquaculture

Aquaculture is the farming of fish and other aquatic organisms for food and other purposes. While only about 13% of the world's fish and other aquatic products come from aquaculture, it is growing rapidly (at 6-7% annually) and it is currently the fastest growing food production sector in the world. Aquaculture productivity depends on a wide diversity of other aquatic or-ganisms for food and for maintenance of water quality. In turn, it can have adverse impacts on the diversity of natural populations of aquatic organisms and the structure of ecosystems through the release of farmed organisms or conversion of one habitat to something else.

Most aquaculture produce comes from about 200 species. Aquatic biodiversity is being lost at alarming rates in natural systems, especially inland waters. The vast majority of this decline has been caused by pollution, human-induced structural changes in aquatic habitats, and the release of introduced species. These losses will constrain efforts to evaluate the aquaculture potential of aquatic organisms. It is already becoming difficult for fish breeders to locate and collect genetic materials from healthy or relatively undisturbed wild populations.

Documentation of wild genetic resources and threats to their survival is the first step toward implementing specific measures to protect the wild population sand their environments. The International Centre for Living Aquatic Resources Management (ICLARM) and FAO have developed a database (FishBase) that now includes nearly half the world's finfish, including nearly all of those that are directly useful to humans.

UNEP recommendations to minimise the adverse impacts of aquaculture on wild stocks:

  • Closed culture: better containment to prevent escape of the organism.
  • Sterilisation: easily induced way of avoiding direct genetic effects.
  • Localisation: locating farms away from wild populations, and choosing locations for sea ranching that minimise straying so as to reduce gene flow to wild populations.
  • Coastal parks: providing totally protected areas for valuable wild populations.
  • Reduced or selective fishing: protecting native populations by reducing fishing pressure or by directing that pressure toward cultured fish.
  • Restrictions on transport: reducing the spread of exotic genes and diseases by restricting transport or live fish and eggs.
  • Gene banks: counteracting extinction of local populations by the establishment of gene banks.
  • Minimal genetic differences from native populations: reducing effects of gene flow by minimising the genetic differences between escaping or released fish and recipient wild popu-lations
  • Training of workers: basic training of aqua-culture workers (including non-specialists) to minimise the risk of accidental releases of organisms into aquatic ecosystems.