Marine aquaculture facilities can suffer severe predation from seals. Underwater aversive audible acoustic devices known as Acoustic Deterrent Devices (ADDs) intended to provide protection by deterring seal approach are used commonly worldwide.
Ocean Science Consulting provides a range of ADDs in the form of low power pingers, or higher-powered seal scarers. If your facility is already equipped with ADDs, OSC can provide cost-effective advice to suit your budget, and/or experimental trials (including underwater acoustic measurements and propagation modelling) to test your devices’ efficacy (see below).
On behalf of clients, OSC has undertaken investigations into sounds made by active ADDs from fish farms. Typically, measurements of Source Level (SL) and power spectra are carried out on commercial ADDs used on salmonid fish farms. Signalling methods tend to differ considerably, and while fundamental acoustic frequencies (including harmonics) are usually similar, energy distribution often varies substantially.
Propagation and Transmission Loss (TL) models in different sea states can be used to estimate potential distances at which marine mammals, such as seals, or for impact assessments, harbour porpoises (Phocoena phocoena) can potentially detect ADDs. Other simulations can also be carried out to investigate sound propagation and TL at particular frequencies by submitting sound profiles measured under oceanographical/bathymetric conditions observed, which vary from location to location.
Marine aquaculture facilities can suffer also from damage to pens/cages or moorings, posing threats to facilities’ income and health of wild fish populations. OSC offers fish-cage and mooring-integrity inspections through its ROV survey wing, providing high-quality underwater inspections and professional post-survey analysis of footage.