Slowing down to save the whales

If we find a marine area full of life that needs protecting, how do we reconcile the need to protect vulnerable marine species against inevitable human presence? Because it is an inescapable fact that much of the ocean is encroached on by humans: cargo ships transport 80% of the world’s goods. Oil and gas rigs use huge drills to get into the Earth’s inner layers. All of this activity leads to a lot of marine noise, which is a big problem for a lot of marine species. What if you’re a whale who wants to chat to a mate, but can’t even hear yourself think? What can we do? The University of Aarhus’ Charlotte Findlay has a proposal which is perhaps the most simple of all: just slow down.

Charlotte - Yes, slowing down is a really effective way of reducing a lot of these impacts from shipping noise to animals. And what we found was that if you slow down even by a small percentage, you can substantially reduce the loudness of your boat. So that's what we call the source level of your boat. And you can also shrink the area around your boat that's being exposed to noise. And as such, that reduces the number of animals that are being exposed to noise. So we found that if you reduce your speed by 20% from the maximum, you can actually reduce the loudness of your boat by six decibels and six decibels doesn't sound like a lot, but that's actually a halving of the noise pressure, which in terms of acoustics underwater is a lot. And then you can reduce the area around the boat that's being exposed to noise by 75%. So it's a real win-win situation. In terms of reducing impacts to animals.

Will - I suppose what appears to be the big issue is that most of these boats will be carrying goods and by slowing them down, are you somewhat disrupting the supply chain?

Charlotte - So of course if you slow down your boats, it's going to take you longer to transport goods. But the really interesting thing is that a lot of these shipping companies that are transporting goods are already slowing down. So they do slow downs when they're trying to save fuel. They slow down when there's over capacity in the market, so there's too many of certain goods. And they also slow down if they know they're going to be sitting outside a port for an extended period of time. And that happens quite a lot actually. So by slowing down, you can actually in some ways save money because you can save money on fuel and you can save money on time that you're spending on the boat. And I think it's important for me just to say that I'm not asking shipping companies to slow down for the entire route between two ports, which you know, could be an entire ocean, but perhaps considering slowing down in areas which we know are important to animals like marine protected areas or coastal areas where we have high densities of animals could have really big impacts on reducing impacts to a number of different species. So the marine mammals that we studied, but also all the other wildlife that's living in those habitats.

Will - And you mentioned earlier about how slowing downwards improve your fuel efficiency, but would it help in the emissions side of things as well?

Charlotte - Yeah, so that's the great thing about slowing down boats. It doesn't just reduce noise, it doesn't just reduce fuel efficiency, but it also reduces greenhouse gas emissions. So it means less carbon dioxide, less sulphur dioxide, less particulate matter. And this is especially important given the climate crisis that's going on and the International Maritime Organization has actually just put into place a law that asks the shipping industry to reduce their greenhouse gas emissions by 70% by 2050 when we compare it to levels measured in 2008. To achieve that, we can potentially use this slowdown approach. And so we are getting a multitude of different benefits from slowing down our big commercial vessels.

Will -
Sounds like a win-win-win here for everyone involved. So it seems extraordinary that perhaps it hasn't been implemented as much as it should be up until this point.

Charlotte - So we're starting to see slowdowns being implemented. So for example, in the port of Vancouver, there is a project to slow vessels down voluntarily and they've actually seen quite good uptake from the shipping companies. They're very keen to be involved and to help to reduce impacts to southern resident killer whales that are living in that habitat, which are also endangered species. So I think it's just a matter of time and I think potentially this could be a really useful tool to the shipping industry if they now know that doing a slowdown could help marine mammals. And they might be able to think about, 'okay, well we could slow down on our transits in certain areas and we'll still save some money and get to port on time, but we can also help the environment.'