Replace or repair damaged anti-predator nets around aquaculture systems
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Anti-predator nets may be placed around fish pens and cages to physically exclude marine or freshwater mammals to reduce predation and human-wildlife conflict. However, such nets may entangle mammals causing injury or death. Frequently replacing or repairing anti-predator nets may reduce the risk of mammals becoming entangled within holes or loose sections of damaged nets (Kemper et al. 2003). This may also prevent mammals from breaching the nets thereby reducing human-wildlife conflict.
For studies that involve modifying anti-predator nets, see Modify anti-predator nets around aquaculture systems.
Kemper C.M., Pemberton D., Cawthorn M., Heinrich S., Mann J., Würsig B., Shaughnessy P. & Gales R. (2003) Aquaculture and marine mammals: Co-existence or conflict? Pages 208–224 in: N. Gales, M. Hindell & R. Kirkwood (eds.) Marine mammals: Fisheries, tourism and management issues. CSIRO Publishing, Collingwood, Victoria, Australia.
Supporting evidence from individual studies
A site comparison study in 2001–2003 of 26 Atlantic salmon Salmo salar farms in the western North Atlantic Ocean, off the coast of Maine, USA (Nelson et al. 2006) found that farms that replaced anti-predator nets more frequently had fewer fish losses to Western Atlantic harbour seal Phoca vitulina concolor predation than those that replaced nets less frequently. Farms that replaced anti-predator nets more than once/year reported fewer losses of fish to seal predation than farms that replaced anti-predator nets once/year or less (data reported as statistical model results). Twenty-two farms replaced anti-predator nets more than once/year. Four farms replaced nets once/year or less. Farm managers were sent annual questionnaires in 2001–2003. Data were collected on methods used to deter predators and estimated numbers of fish lost or damaged due to seal predation.Study and other actions tested