The links between marine animals killed by heatwaves and those killed by industrial fishing
More than a billion marine animals - mainly mussels, but also clams, starfish, and sea snails - have cooked to death due to the intense heatwave that battered western Canada at the end of June and killed more than 700 people. A marine biologist at the University of British Columbia recorded temperatures exceeding 50 degrees Celsius along the coastline - unsurvivable heat even for hardy bivalves.
There are likely to be ongoing impacts from this and future heatwaves fuelled by the climate crisis. "The craziest thing is that it's just the tip of the iceberg," marine biologist Malin Pinksy told NPR. "We can see the mussels because they're on the shoreline, but to a large extent, oceans are out of sight, out of mind, so we're likely to learn the magnitude of what's happening only much later." Beyond specific extreme weather events, warming ocean temperatures in general are also taking a toll on marine animals and harming marine biodiversity around the equator.
For every sea creature lost to the effects of climate change, there are many more that are lost to industrial fishing, which in turn is helping to make the planet hotter.
The huge trawl vessels that catch millions of fish are known to trash the ocean floor, but recently it’s also become apparent that they are releasing significant amounts of carbon too. Burning fossil fuels to power fishing vessels was responsible for 207 million tonnes of carbon dioxide emissions in 2016 - almost as much as that emitted by 51 coal-fired power plants in the same timeframe. But greenhouse gases are also released from seabed sediment into the water when it is disturbed by industrial bottom trawlers, according to a study published in Nature in April 2021. Using satellite-inferred information, the researchers estimated that a staggering 4.9 million km2 (1.3 per cent) of the global ocean is trawled each year.
The release of carbon dioxide from the ocean floor also contributes to ocean acidification, which reduces the prevalence of carbonate ions that can be used as building blocks of corals and of seashells, like those belonging to the mussels killed by Canada’s heatwave, making it harder for these organisms to build and maintain their structure.
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“Marine sediments are the largest pool of organic carbon on the planet and a crucial reservoir for long-term storage,” the researchers write, and “protecting the carbon-rich seabed is a potentially important nature-based solution to climate change.” That means greatly expanding marine protected areas (currently only about seven per cent of the oceans have any protection) and banning trawling and other extractive activities from them.
Banning trawlers from more of the ocean would also save a lot of fish from a lot of pain. Up to 2.3 trillion fish are estimated to be caught from the wild every year, injuring and killing around 300,000 whales and dolphins that are accidentally caught in the process. And the numbers just keep rising; according to the Food and Agriculture Organization, in 2018 there was a 5.4 per cent increase in the total global volume of fish caught through capture fisheries compared to the average of the previous three years. That amounted to 96.4 million tonnes of fish - the highest level ever recorded.
The scale of suffering is difficult to grasp - because the fish do suffer. There is clear scientific evidence showing not only that fish feel pain but that they actually seek out positive experiences and avoid negative ones. When caught in the wild, they can die from decompression as they are pulled up through the water, causing their internal organs to explode. They can die from suffocation out of the water, or from injuries sustained during capture. They can die from being crushed under the weight of other fish in the nets. Distressed and desperate to escape, they thrash about, sometimes sustaining further injuries.
If they’re discarded, they still experience stress and injury due to being lifted onto the vessel deck, being handled and exposed to the air, and through the discarding process itself, which not all fish survive.
The loss of so much life from a single heatwave is frightening and tragic. But far worse is that such events are allowed to happen as the seas continue to be plundered, despite all the evidence that it is to the detriment of all life on Earth.
Claire Hamlett is a freelance journalist, writer and regular contributor at Surge. Based in Oxford, UK, Claire tells stories that challenge systemic exploitation of and disregard for animals and the environment and that point to a better way of doing things.
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