Maintaining high standards of fish welfare is a top priority for fish farmers, and for many farms operating in open waters, protecting fish from predators is an essential part of fish welfare. Often the most challenging balancing act is creating a safe environment for your fish while also minimising impact on other marine life. The Marine Mammal Protection Act (MMPA) has recently prompted renewed interest in how predator deterrent technology has evolved to be both effective and environmentally responsible.
How do predators impact fish health?
Discussions about fish welfare often focus on the interactions between fish and people, but there is also the interaction between fish and predators to consider. When predators like seals or sea lions are present at farm sites, they can cause high levels of fish stress and, also, a lot of mortalities if the right protections are not in place.
Fish mortalities from direct seal attacks are the most visible and gruesome consequence of predation but there are also other, less immediately obvious, impacts on the fish. Even with a physical barrier like anti-predator netting in place, a seal circling the pen can be stressful enough to put many fish off their feed and even cause some fish to fall to the bottom of the net out of exhaustion. And, in the case of exhaustion, these fish are then an easy target for the predating seals.
With upcoming MMPA regulatory changes, farms are looking more and more at environmental impact when assessing the methods they use to keep predators at bay.
What is changing and who is impacted?
When new import provisions of the MMPA come into play on January 1st, 2022, the USA will ban fish product imports from countries whose farming operations cause “mortality and serious injury of marine mammals”. NOAA Fisheries, the American organisation responsible for the MMPA, defines “serious injury” as “an injury that is more likely than not to lead to the death of the affected marine mammal”.
It’s important to understand the MMPA is not a ban on acoustic devices or any particular technology; the focus is on reducing mortalities and serious injury. One thing that will be impacted though in countries like Scotland is the last resort option, that currently allows farms to apply for a license to shoot seals.
Changing measures in Scotland
The Scottish salmon industry, with exports to the USA currently worth UK £179 million a year, is investing a lot of time investigating potential impacts of the MMPA. An industry wide drive to reduce seal mortalities has already led to large reductions in the number of seals being shot, but to be MMPA compliant this will no longer be an option at all in future. Farms have known about this change for several years and have been improving their technology and processes in preparation.
In the early 2000s, when farms were exploring more ethical approaches to deterring predators, many farms looked to either acoustic deterrents or reinforced netting. Technology in this area, particularly acoustic technology, has advanced a lot since those early days.
Read more, HERE.
The Aquaculturists
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