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In Tasmania, farmed Atlantic salmon may be vulnerable to attack by seals and sea birds.
Maintaining good fish welfare by protecting farmed Atlantic salmon from predators, such as seals and sea birds is critical to the RSPCA Approved Farming Scheme standards. Fish are vulnerable to stress, injuries and mortalities as a result of interactions with predators.
The RSPCA believes that exclusion measures, both above and below the water, must be the primary method of preventing seals and sea birds from attacking salmon. Over recent years pen net technology has become very sophisticated and is more effective in keeping predators out and fish safe.
With these improvements in pen security, seals usually only get access to the salmon pen if there has been damage to the netting, most often caused by storms. Birds, often cormorants, sometimes find their way through holes or become ensnared in the netting. Birds that get inside the pen have places they can perch and sometimes find their own way out through specially placed ‘bird escape holes’.
At the same time, safeguarding the welfare of seals and other predators is important. The use of seal deterrent devices must meet the requirements set out by the Tasmanian Government.
The RSPCA Approved Farming Scheme Standards – Farmed Atlantic Salmon, prohibits the use of bean bags, scare caps, electronic seal scarers and pingers.
Where seals have been able to breach a pen’s outer netting and are causing harm or distress to fish, seals must be given the opportunity to swim out of the pen on their own accord. This is done by lowering outer nets.
In instances where seals don’t swim out of pens on their own and as a last resort, in order to protect fish welfare, the RSPCA Approved Farming Scheme will permit the limited use of crackers in accordance with Tasmanian Government requirements. If a seal or seals inside the pen do not voluntarily swim out after lowering of the nets, crackers can be dropped in the water nearby so that the seal swims away from the flash/noise and out of the pen. Based on existing research, crackers appear to have the least potential to cause harm to seals as a deterrent device.
There is very limited research available on the immediate and longer-term effects of deterrent devices on seal welfare. The RSPCA urges the Tasmanian Government and the salmon farming industry to invest in this area.