Predator Control

Behaviour versus barrier

Ace Aquatec has pioneered new generation ASR (acoustic startle response) deterrents that work by changing behaviour rather than by building a barrier, like the old style ADDs.

Predators are first conditioned to avoid low volume noise, and then a conditioning signal across a wide range of frequencies provokes a startle response. Seals respond rather like cows touching an electric fence or being startled by unexpected noise.

Older ADDs that erect a temporary acoustic wall around a pen, similar to a constant burglar alarm, are vulnerable if there are holes in the ‘fence’. But because Ace Aquatec deterrents create a behaviour, not a barrier, breaks in the acoustic signal don’t lead to a window for predation.

Science behind the signal

The three key elements of the Ace conditioning signal are the low duty cycle (on/off periods); the low average volume (less output); and the low frequency (pitch).

Low duty cycle

The duty cycle is important because it affects temporary or permanent deafness (threshold shifts) in seals or non-target species. Our sound approach means we can run with a reduced duty cycle because we can create conditioned avoidance due to the quality, not the quantity, of the sound. Acoustic barrier systems require long duty cycles to be effective (like a fence they must have no holes).

This is a critical factor for NOAA (which regulates the US Marine Mammal Protection Act) and EPS (European Protected Species) licensing because low duty avoids injury to the hearing of co-existing wildlife around farms.

Low average volume

Ace’s signal involves far less acoustic output into the water than barrier systems. Just 10 milliseconds from the onset of the sound to its highest peak creates a visceral response in mammals that cannot be overcome.

Successive encounters with this noise create sensitisation (gets worse) rather than habituation (gets used to it) which means that sound is more impactful at lower volumes on successive encounters.

Our system keeps being effective because we randomise the frequency of the pulses, the volume of pulses and the duration of silences.

Low frequency

Ace Aquatec’s targeted frequencies ADDs are tailored to the sensitive hearing range of mammals; our randomised computer-generated sound patterns in the mid-frequency system are designed specifically to avoid the hearing risks and habituation effects associated with single frequency systems; and our low frequency system avoids the hearing ranges of non-target species.

Product

ACE ASR US3

Mid-frequency (8-11kHz) acoustic deterrent that offers proven long-term effectiveness; wide frequency spread that avoids threshold shift and habituation; and automatic duty cycle ramp down, which ensures the deterrents don’t stay on permanently after the initial automated activation (see AI Trigger below).
This removes the need for manual intervention by the farm staff.

Product

ACE Intelligent Portal

An advanced monitoring and activation platform for controlling deterrents remotely, the portal can adjust the performance of deterrents, receive automated alerts if a system goes offline, and easily mute systems for divers.

Compliance

NOAA and MMPA

The MMPA (Marine Mammal Protection Act) will ban fish product imports from countries whose farming operations cause mortality and serious injury of marine mammals. NOAA Fisheries, which is 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’.

Both the Ace US3 and RT1 acoustic deterrents have been certified through NOAA’s easy-to-use website deterrent tool, allowing all users of our equipment to continue exporting to the US under the MMPA when its new import provisions come into force on January 1, 2022.

Compliance

Marine Scotland and EPS

Since March 2021, the Scottish Salmon Producers Organisation (SSPO) announced that the sector is no longer using ADDs that may have been considered to cause disturbance to European Protected Species.

Only new generation acoustic deterrents that use a different range of frequencies and volumes to help deter seals, while better safeguarding cetaceans, and comply with both Marine Scotland and US MMPA requirements, will be allowed.

Operators have to provide evidence from suppliers of their devices’ compliance.

Sound profiles must be mapped to see the impact in terms of ‘injury’ and ‘disturbance’. Marine Scotland methods for calculating injury are well established but, currently, there is not an accepted sound threshold level for behavioural disturbance to marine mammals.

Ace Aquatec has zero injury using Marine Scotland’s deterrent tool, and the lowest disturbance of any acoustic system, which can be lowered further to zero.

We work with leading acoustic scientists like Alex Coram (Sea Mammal Research Unit (SMRU) and Jeff lines Silsoe Research Institute who compiled an automatic generator and mapping tool (based on Marine Scotland’s own parameters) to make EPS application as straightforward as NOAA’s online MMPA certification system.

Ace is requesting that frequency weighting be accounted for in the Marine Scotland model (currently it is not incorporated). But even without frequency input in this model, Ace’s US3 and RT1s cause no injury and the lowest disturbance of any systems, providing a path to continued acoustic use.

History of innovation

Ace Aquatec’s R&D journey, from acoustic startle innovation to AI triggers, has progressed over more than two decades and resulted in award winning, technological breakthroughs.

Inventor and company co-founder John Ace-Hopkins, together with Gavin Haywood, made a presentation on the Management of Seal Predation at the 1995 Scottish Aquaculture Conference, outlining their philosophy on the difference between the acoustic startle methodology of the Thomson Marconi, versus the Airmar barrier approach.

Then, from 2001 to 2004, Ace Aquatec developed a means of improving the startle response by using a fish motion detector trigger to elicit a 3-4khz training tone, before a louder startle noise.

With the subsequent development of the ASR US3 and ASR RT1, came academic validation that Ace’s acoustic signal was 50% more effective than alternative deterrents on the same farms (K. F. Whyte 2015, Investigating Seal Depredation at Scottish Salmon Farms), and the range was greater (Goetz 2008).

Ace focused on thermal imaging after tests on captive seals showed that short periods of targeted sound were more effective and less likely to result in habituation than operating deterrents continuously (Kastelein 2006).

And Ace developed the electric fish following tests on how electric fields prevented seals from taking a freely available food source (Sarf071: Behavioural Responses of Seals to Pulsed, Low Voltage Electric Fields in Sea Water; D Thomson et al).

Further research

Ace Aquatec has SAIC (Sustainable Aquaculture Innovation Centre) funding to further validate the fact that porpoises cannot hear the RT1 deterrent.

We have developed our systems with Scottish government backing and with the support of leading salmon farmers, including Scottish Sea Farms, the Scottish Salmon Company and Loch Duart, as well as with retailer Marks & Spencer.

Future proof

The recent advances in acoustic technology embraced by Ace Aquatec enable farms to take a blended approach to predator control. The most successful safeguards against predation will be a combination of new generation acoustics, reinforced anti-predator netting, and good farming practices. Taken together, such measures will ensure that farms, fish and other marine mammals all thrive within the new regulatory framework.