Finnish trout farmer finds Ace solution to seal problem
06 February 2024
A Finnish rainbow trout farmer plans to install Ace Aquatec’s acoustic startle response technology across its farms after trials last year proved successful in combating seal predation.
Laitakarin Kala currently operates two farm sites in the brackish waters of Bothnian Bay in northern Finland, where the winters are long, the growing season short – and the seals hungry.
Co-owner and Production Manager Timo Karjalainen said they were losing up to 20 tonnes of fish out of a total annual output of around 200 tonnes in the past years due to seal predation. In 2023, their total annual output was approximately 800 tonnes, which they expect will grow up to 2,500 tonnes in a few years.
The installation of eight A-ASR®(Acoustic Startle Response) US3 devices at the company’s Vatunki site from April to December 2023, as well as minor changes to the net pens, made a significant difference, with no fish lost to predation in that period.
‘We changed the whole farm, including putting in a sinker tube, which keeps the net tight, as well as the US3s,’ said Karjalainen. ‘Since then, we are certain that these devices are working, because although the seals still approach the wider area, they do not attack the pens.’
He highlighted the flexibility of the A-ASR® systems, which can be battery powered on more remote sites but can also be powered by energy grids. The devices on Laitakarin’s pens were predominantly battery powered before the upgrade, but now a new energy grid, supplied to the farm from a power cable running from the shore base to the pens, has enabled remote monitoring and control of the acoustic devices, cameras and feeding systems.
‘There are back-up batteries in the event of a power cut, but the staff no longer need to check battery levels daily in order for their site to perform optimally.
‘In 2024, we will have more pens and will need more A-ASR® devices. The fact that they are very easy to install and maintain is important because in the winter here we have to take them out of the water when the ice comes and then put them back in the spring.’
The ice came early in 2023, in November, and the fish were moved and all devices have been placed into storage, ready to be deployed again between May and December 2024, but the devices installed last summer kept the pens protected during what is typically the worst period for seal attacks.
Ace Aquatec will be back in Finland in May to help set up devices in six pens at Vatunki, where trout has been farmed since the 1970s. A further six units will be installed at the company’s Martinniemi site, which trialled two A-ASR® devices in 2023 and is now expanding. A third site, which is offshore, will come online in the coming years, with an application submitted for another 1,000 tonnes.
The mid-frequency A-ASR® device uses a triggered mechanism to produce low-volume noise, provoking a startle response. Its randomised computer-generated sound patterns avoid the hearing risks and habituation effects of single-frequency systems.
Ace Aquatec Marine Protection Products Business Manager Andrew Gillespie-McLean, who was in Finland last year to install the trial units, said: ‘The problem with traditional deterrents is that they deliver an acoustic wall of sound around a pen, which can cause deafness and habituation in seals and not a behaviour change. They also require long duty cycles to be effective.
‘Our systems work on creating conditioned avoidance. We use complex high rise time tonal bursts to create sensitisation sounds, which become more impactful at lower volumes. We can also randomise our output frequencies and break up the acoustic signal to include longer silences between sounds, which produce much shorter duty cycles. This approach stops seals becoming habituated and forces a change in their behaviour.’
‘Our A-ASR® device does not cause any harm to the seals, or any non-target species, as the sounds are well below acceptable thresholds.’
Timo Karjalainen’s grandfather was an early pioneer in Finnish trout farming and Laitakarin Kala’s Vatunki site is seen as a test bed for new technology and innovation. Last year, it hosted a visit by members of the Finnish fish farmers’ association to demonstrate how the A-ASR® devices work. The company also has a close relationship with Natural Resources Institute Finland (known as Luke), which has been researching Ace Aquatec’s A-ASR® systems at two coastal locations in conjunction with local fishermen.
‘The results of those trials provided strong scientific validation of the A-ASR® in these conditions above any competitor system, which will give the fishermen the confidence to use our acoustic startle response systems commercially,’ said Gillespie-McLean.
Having seen the positive effects of the A-ASR® systems, Laitakarin Kala is now also looking to install Ace Aquatec’s A-BIOMASS® camera for trout.
‘Timo’s company is a perfect fit for Ace Aquatec as they are an early adopter of technologies and share the forward-thinking mindset that we look for in our partnerships,’ said Gillespie-McLean.