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Tiny pieces of plastic represent a huge problem for ocean giants

Posted by Willie Mackenzie - 7th March 2018

Recently humpback whales have been hanging around in the Firth of Forth, the tidal estuary in Scotland near Edinburgh where the river becomes the North Sea. These gentle giants have drawn gaping crowds locally, amazed to see such impressive beasts so close to shore. On the other side of Scotland, huge basking sharks, as much as 11metres long, coming to feed in clear Hebridean waters are both a conservation success story, and a welcome boost for local tourism. Yet the presence of these enigmatic ocean beasts belies an invisible problem they both face: their oceans, and stomachs, are filling up with our plastic rubbish.

Basking sharks and humpback whales are filter feeders. Both exist by eating lots of tiny plankton, but how they catch it varies:

Being fish, basking sharks filter mouthfuls of water, effectively straining it through their gills and swallowing what they catch. They can filter as much as 2.5 million litres of seawater in an hour – enough to fill a 50 metre Olympic swimming pool! Humpback whales are from the baleen whale family, instead of teeth they have plates of ‘baleen’ in their mouths that allow them to strain out food from sea water. They open their mouths wide, their throats ballooning open, and close down on a massive mouthful of prey. They then force the water back out through the baleen plates and swallow down the food they have caught.

Neither basking sharks, nor humpback whales have any way to distinguish between small prey animals and marauding morsels of plastic waste, so they are also now chowing down on plastic soup.

One rubbish truck’s worth of plastic gets into the ocean every single minute – that’s as much as 12 million tonnes each year. It doesn’t go away. It might sink, or float, or wash up on a beach, or break down into smaller pieces – but it doesn’t disappear.

Increasingly ocean wildlife is suffering because of plastic pollution, with large pieces of plastic entangling, injuring or choking endangered turtles, whales and seabirds around the globe.

But a new scientific study has drawn awareness to the impact on some of the world’s biggest creatures from some of the smallest pieces of plastic. The report draws attention to the possible impacts of toxins attached to the plastic particles. Basking sharks, their bigger tropical cousins the whale sharks, and graceful mobula and manta rays are all long-lived, slow growing filter-feeding fish. Humpbacks are just one of a whole family of long-lived filter-feeding whales that includes the arctic bowhead, minke whales and even the biggest of them all, the gigantic blue whale. Microplastics in sea water now represent a real threat to all of these animals.

A basking shark on the west coast of Scotland.

It’s not yet clear what the long-term impacts of eating plastics will be on these species, but given the evidence from mussels and oysters ingesting microplastics, and knowing that the toxic legacy of persistent pollutants is pushing species like orcas towards extinction – it certainly doesn’t look good.

Of course, this shouldn’t be happening, and we need to stop the flow of plastics into our ocean, which is why Greenpeace is campaigning to get Governments and plastic-producing companies to take urgent action on plastics to save our most precious marine life.

And this video taken in Bali this week shows the scale of what that marine life is up against:

Whilst we don’t yet know what the impact of whales, sharks or mantas eating this microplastic will be – and it may take decades for us to understand them, but this has to act as an alarm bell for all of us to demand action. Stopping so-called ‘single-use’ plastics, or excessive plastic packaging isn’t just a trend or cause celebre, it’s vital if we want to protect the gentle giants roaming our seas for generations to come.

Find out how you can do more to reduce your own plastic footprint and help us get governments and companies to tackle theirs too.