French oceanographer Jacques Cousteau called the ocean ‘the silent world’, but Dr Craig Radford says it’s actually very noisy in the sea. Not only do marine mammals communicate with each other through sound – many fish species do, as well.
Craig been recording these sounds and studying just how and why fish make them. He talks with Jesse Mulligan.
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Jesse Mulligan: What are the effects of human-made noise [on fish sounds]?
Craig Radford: We’re just starting to understand the sound the fish is using and why they’re using it. It’s only now we’re coming to grips with ‘How is all this sound we’re putting into the ocean affecting the day to day life of these animals?’
A report came out of the US in the early 2000s saying that the ambient noise, the actual background noise of the ocean, has increased by 3DB per decade since the 1970s. 3DB equates to a doubling of sound intensity. This was mainly attributed to the low-frequency sound of ships.
The effects can be masking effects – they can mask the sounds that the fish are producing, they might not hear them. A bit like the ‘cocktail party’ effect, right? If they’re surrounded by a whole lot of noise, do the fish talk louder or do they have the ability to talk louder or do they just get drowned out?
Dr Craig Radford is a senior lecturer at Auckland University's Institute of Marine Science.