Lindy Weilgart, a Californian living on the east coast of Canada, has spent her life chasing sperm whales, the species of whale immortalized in the novel Moby Dick. But Weilgart does not carry harpoons or weapons, but only instruments to add arguments to preserve cetaceans and to measure the effects of underwater noise pollution on marine species. Once, she even spent a year at sea, accompanied by her still young children, to follow the migration of whales from America to New Zealand.
One of the world's great specialists in underwater noise, Weilgart has spent a few days in Barcelona invited by Ocean Care to present her conclusions on how to achieve quieter waters for whales and dolphins, reduce the risk of ship collisions with cetaceans, and reduce the emissions of greenhouse gases and polluting gases in the sea and the atmosphere. And to shore up the scientific basis of the Mediterranean Cetacean Migration Corridor, an already approved Zepim (Specially Protected Area of Interest for the Mediterranean) for which the management plan is being prepared.
What would we hear in the sea if there were no noise?
We would still hear sounds but they would be natural... the waves, the fish, the whales... they would be biological sounds. Noise generated by human activity is more harmful because animals are adapted to natural sounds. And not everyone can adapt to the noise of now. Fish that live three years can't. Instead, the whales, which have long lives, up to 200 or 250 years, can adapt.
If they live that long, there will be whales that sailed the waters before the industrial revolution and propellers
Well yes, we know that bowhead whales live so long because ivory harpoon tips were found stuck into their skin and it was later verified by other means. So suddenly one day the industrial noise appeared in the seas they sailed.
Why is it important to reduce underwater noise in the oceans?
In a report I wrote that there are about 150 marine species that are affected by noise in different ways, some even serious that can endanger the health of the species. I'm not just talking about cetaceans, but also about fish and invertebrates, including plankton.
Can they even go deaf?
That is one of the serious consequences, but not the only one. It can kill plankton, for example. It causes high mortality rates in scallops, too. And it affects the ability to communicate, because fish communicate with sounds. Reproductive rates drop: the fish end up reproducing less and are unable to care for their spawn. We know that stress increases with the noise of the boats. And, very important, the masking effect, the noise erases the sound that cetaceans and other species need to communicate with other members of their group, or to hear the sound of their prey, or their predators, or the waves, they need to orient themselves. They are very important for the survival of the animals and the noise of the boats cancels them out.
What is the most important thing that you have explained these days at the Oceannoise2023 conference in Vilanova i la Geltrú?
I have presented the report that I have prepared for the UN convention on migratory species, which are a series of technical recommendations called Best Available Technologies (BAT, Best Available Technology) and Best Environmental Practices (BET, Best Environmental Practices) for mitigate noise sources. These sources are basically maritime navigation, seismic surveys and the construction of offshore wind farms, but what most concerns Spain is undoubtedly the noise generated by maritime traffic, and luckily that is the easiest cause of noise to deal with. because it is circumstantial. Everyone wins with quieter boats.
Is noise a problem common to all the seas and oceans on the planet? Or is it especially worse in the Mediterranean?
In the Mediterranean the situation is very bad. In the North Sea too, in Gibraltar, in the English Channel, around all lines of maritime traffic. In the northern hemisphere it is much worse than in the south
Is it a matter of the volume of boat traffic?
Yes, in the Mediterranean there are about 200,000 ship movements every year, it is one of the areas with the most intense traffic. On the other hand, in Spain there is no seismic activity linked to oil and gas exploration, although the noise travels very far, it can reach hundreds of kilometers. Even the noise that is generated in Libya or North Africa can be heard in this part of the Mediterranean.
What is the most worrying thing about noise?
In this case, the whistle of ships, which is produced by the ship's propellers, especially at high speeds. The faster the boat goes, the more cavitation occurs, that is, the bubbling and the wake. Most boats start to cavitate at twelve knots, so we know that one of the easiest ways to reduce noise is to reduce boat speed. We know that 95% of ship noise comes from cavitation.
Does making the boats sail slower fix the problem?
Measures can be taken in the design of the hull and the propeller, that can also reduce cavitation, but what we recommend is to go slower, it is a measure that can be implemented now, without the need to redesign the boat. I can cite eight advantages of the so-called low stemming: more efficiency and therefore spend less money, less greenhouse gas emissions, less nitrates, less toxic emissions, less suspended particles, less soot particles, and fewer collisions with cetaceans. Just a 10% reduction in speed reduces the area affected by noise by 40% and that's already a huge benefit. For a whale or a fish it means a lot.
Is it one of the great threats to whales?
I cannot categorize the threats, because the whales suffer from hunting, collisions, noise and more factors such as pollution, overfishing... But it is one of the most invisible dangers for whales. Noise is sometimes a silent killer. Because it is difficult for us to prove when the noise is the cause of some misfortune. For example, there have been many cases of whales stranded on the beaches of the Canary Islands in which it has been possible to establish a relationship with the sonar of ships. The stress caused by noise is invisible.
Are the big shipping companies aware and will they agree to reduce the speed of their ships?
I think so, really. The World Maritime Organization (WMO) considers it a big problem and has already published a guide for the reduction of marine noise and the European Union is preparing new maritime strategy directives. In fact, a study says that noise has doubled in all European waters between 2014 and 2019. And there are a series of binding objectives, such as that no more than 20% of the affected habitat can be lost, that shipping companies will have to respect. They will have no choice but to join. But, in addition, it is that the shipping companies will save money if their ships go more slowly.
Does it already happen in any country?
I know that in Spain agreements have been reached with MSC and other companies and they have agreed to change their routes to avoid collisions and reduce speed to mitigate noise in the ocean. Many measures are voluntary now but will be mandatory in the future. It is always better to go ahead. Like in Canada.
Does Canada serve as an example?
They are leaders in this matter. And the example of the killer whales of the Pacific Northwest, around Seattle and Vancouver, is very illustrative. There, cetaceans are greatly affected by noise, pollution and the scarcity of fish such as salmon. Orcas don't have enough food, they starve and must draw on their internal stores of fat, but this releases toxins into their blood and they also have difficulty using their biological sonar and this prevents them from hearing the echoes of their prey. It's like a big domino effect.
And have the authorities intervened?
The Port of Vancouver decided to protect the orcas and has decided that the quietest boats pay up to 75% less in port fees. Just as there are weighing stations for merchandise, they have installed stations to measure the noise of ships. So shipping companies save costs. We'd like to see that on many other sites. France prepares a slow steaming map. Spain also has to start drawing up a 'decarbonization' map of maritime traffic and the management plan for the Mediterranean Cetacean Migration Corridor. There are several technological measures available to reduce the speed of ships.
The news of sightings in Catalonia have recently skyrocketed
April and May are good months to be seen in the area of this Mediterranean corridor, but the sea is not a laboratory that you control, but it is so difficult to follow the trail to find out why things happen in cetacean communities that it is better to go to what sure, and that is to focus on noise reduction. Quieter is always better.
