Biological Control / Natural Grazers

Other than the marketable stock species, an additional species can be cultured alongside the stock that consumes the undesirable fouling on stock or infra-structure. The CRAB project looked into the use of sea urchins as an example and more details can be found on the research pages or in the Best Practice Guidelines, which can be downloaded from the site. Preferably, this second species is also profitable in the form of a polyculture.

Applicable to:

- Stock and infrastructure.

- Infrastructure (nets, moorings etc).



- Grazing and omnivorous species that feed on the species which make up the fouling community are included within the aquaculture infrastructure. Through their actions fouling levels are reduced.

Key Factors Positive

- Environmentally friendly, no chemicals released and no large scale removal of fouling material necessary.
- Less frequent cleaning can help to reduce the levels of stress and mortality in stock species.

Key Factors Negative

- The levels of fouling reduction can be variable depending on the control species available.
- The selected control species often need shelter or refuge from extreme conditions.
- The choice of control species is important as there is a need to be sure it will be tolerated by stock species.

Cost Benefit

- As yet the benefits in fouling reduction do not translate into a saving from reduced cleaning costs associated with other strategies (see Best Practice Guidelines for more details).

Conclusions/ Discussion

- The experiments from the CRAB project suggest there is potential for this strategy in fouling management.
- However, strategy needs refinement and probably to be combined with other techniques to maximise the benefits and become viable from a cost perspective.

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