Underwater noise
Water is an ideal medium for the propagation of sound: acoustic
waves travel four times faster than in air and sound attenuation is
considerably less.
Most marine mammals (whales, dolphins, porpoises and seals),
many marine fish and even some shellfish use sound to communicate,
to locate mates, to search for prey, to avoid predators and
hazards, and for short- and long-range navigation. Humans are
engaged in a number of activities that produce underwater sound
which can affect marine organisms in various ways. Anthropogenic underwater sound can mask
important signals such as echolocation clicks or communication
calls; it can lead to a variety of behavioural reactions; it can
result in hearing loss; and at very high received levels, sound can
injure or even kill marine life. The distribution and level of
sound generating activities is very difficult to quantify and
long-term data on trends in ocean noise is patchy. There are
considerable gaps in our understanding of the effects of noise on
marine life - for example on behavioural reactions - which make it
very difficult to assess effects conclusively.
We have a wide range of expertise on underwater noise.
We conduct playback studies to investigate behavioural effects on
fish, model ambient noise profiles based on field measurements
and are developing risk assessment frameworks for noisy
activities. Cefas also provides advice and undertakes research
on underwater noise for the UK government (DECC, Defra) national
organisations such as COWRIE (Collaborative Offshore Wind Research
Into the Environment) and the ALSF (Aggregate Levy Sustainability
Fund). Our international list of customers includes the
International Association for Oil and Gas Producers and the Danish
Government. Last but not least we provide leading input into
international policies dealing with noise such as ICES
and OSPAR.
