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Research Document - 2010/025

Pathways of effects of noise associated with aquaculture on natural marine ecosystems in Canada

By Peter F. Olesiuk, Jack W. Lawson, and Edward A. Trippel


The purpose of this document is to examine the pathways of effects of noise associated with aquaculture on natural marine ecosystems in Canada. Aquaculture, like most maritime activities, generates sound as a by-product of ongoing operations, and sound may be associated with constructing, maintaining, and decommissioning aquaculture facilities. In some cases, intense sounds have been intentionally produced to deter predator (seal and sea lion) attacks. Water is an excellent medium for transmitting sound, which can propagate tens or even hundreds of kilometres from the sound source. Aquatic organisms utilize sound for communi­cation and foraging, and some species have their best hearing sensitivities within the dominant frequency ranges of sounds produced by aquaculture operations. The use of sound and hearing sensitivity is particularly advanced in marine mammals, which probably serve as good indicators of the potential effects of noise. Relatively loud sounds can potentially invoke behavioural responses and avoidance, interfere with or mask communication and echolocation signals, and cause temporary or permanent hearing loss. As a result, noise can displace animals from their habitat or interrupt normal movement or migration patterns, adversely affect foraging and reproductive behaviour, and increase the risk of predation. Acoustic Harassment Devices (AHDs) used to deter seal and sea lion attacks at salmon farms have been shown to have far-ranging effects on non-target cetaceans, such as harbour porpoise and killer whales, which can be displaced large distances from where AHDs have been deployed. In contrast, pinnipeds (seals and sea lions) appear to habituate to these devices and may experience hearing loss through prolonged exposure or very close approach, such that AHDs are largely ineffective as long-term predator deterrents. AHDs could potentially disrupt the behaviour patterns of some fish that have specialized hearing apparatus, particularly clupeids like herring, but these effects have not been documented. Given their ineffectiveness as deterrents and far-ranging impacts on non-target species, including SARA-listed species, it is recommended that AHD use at fish farms be prohibited. Sounds, particularly from vessels and their sonar, are also routinely produced during normal operation of aquaculture facilities, and may have localized or transitory effects on aquatic animals and are contributing to the chronic problem of increasing levels of anthropogenic noise in the oceans. It is recommended that the industry adopt practices to minimize noise and propagation, especially within or near Ecologically and Biologically Sensitive Areas (EBSAs), and near the important habitats of SARA-listed species. Aquaculture might, in a few circumstances, produce more intense sounds if underwater blasting or pile-driving is used during construction and demolition. These intense sounds were beyond the scope of this assessment, but could potentially harm aquatic animals and should be managed the same as other industrial maritime activity. Ocean noise and its effects on aquatic ecosystems are not yet well known, making it difficult to predict the impacts and fully appreciate the ecological consequences of far-ranging behavioural responses to aquaculture noise. We advocate the continued monitoring of sensitive ecosystem components, particularly cetaceans, in the vicinity of aquaculture operations and vessel traffic.

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