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Blue whales and the menace of microplastics – how we’ll solve this problem

Our love affair with plastic began in the 1950s when it revolutionised manufacturing. But what happens when you use a material that’s built to last for ever to mass produce products that are designed to be thrown away? Let’s explore.  

If you’ve seen a blue whale feed, you’ll know that they take enormous gulps of seawater and then filter their food – miniscule, shrimp-like creatures called krill, as well as tiny fish - from the water. Each mouthful can contain up to 80,000 litres of water … and a lot of microplastics.

Microplastics are pieces of plastic that measure less than five millimetres long, but they can be so small that we need a microscope to see them. They are either created purposely as small particles, called ‘nurdles’, used in manufacturing; or over time as plastic breaks down due to wear and tear (e.g., your polyester jumper shedding fibres during a wash) or exposure to sun, wind and waves (e.g., a piece of plastic litter on the beach).

microplastics on beach
Millions of nurdles ended up on Sri Lankan beaches after a container ship caught fire in 2021

Mind-boggling amounts

Microplastics accumulate through the food chain from the smallest organisms to the largest of the whales. Phytoplankton (microscopic plant-like organisms) and zooplankton (microscopic animals such as krill) seem to like eating microplastic, then they get eaten by fish that get eaten by bigger fish, and so forth. Microplastics occur at highest concentrations at depths of 50 to 250 metres, the depths at which some filter-feeding whales like to feed.

A study published in November 2022 showed that krill-eating blue whales could ingest up to 10 million microplastic pieces every day - that’s about 43.6 kilograms or the weight of an average 13-year-old human. Only about 1% of the swallowed plastics come directly from the seawater, the other 99% come prepackaged in the food the whales eat. This means that, because blue whales are so enormous and gulp such large quantities of krill whilst feeding, they are at much greater risk of ingesting mind-boggling amounts of microplastics. A mainly fish-eating humpback whale by comparison might consume up to 200,000 microplastic particles per day, that’s 50 times less than the blue whale, whilst a krill-eating humpback could consume up to four million microplastic particles.

blue whale
A blue whale can eat the weight of a 13-year-old human in microplastics every day

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Unknown impact

What the consumption of such enormous amounts of microplastics means for the health of the whales is still unclear. There is the unknown toxic risk that the chemical composition of the ingested particles poses, as well as the possibility that the microplastics will most likely break down into even smaller nanoplastics in the stomachs of the krill and the whales and be rereleased into the environment when the whales poo. At the very least, carrying around that indigestible extra weight could mean that the whales are burning up more energy.

Plastic in the ocean
Plastic litter breaks down into microplastics that never go away

Compounded pressures

Environmental crises like this do not exist in isolation – they are intricately interconnected and mutually reinforcing. The United Nations report Making Peace with Nature substantiates this and urges member states to better align goals, targets, commitments and mechanisms under environmental agreements to be more effective. A new global plastics treaty could hold the potential to radically reduce the human threats posed to whales and dolphins, not just from ingestion and entanglement, but from climate change, chemical pollution and biodiversity loss.

What we're doing

I work through various international bodies to reduce the impact of plastic pollution on the marine environment and on my beloved whales, dolphins and porpoises. One of these is the International Whaling Commission (IWC, the body that regulates whale hunting). As the forum where the governments of the world make decisions about the conservation and welfare of whales and dolphins, the IWC has a key role to play in understanding and addressing the impacts of plastic pollution on them.

So, at the most recent IWC meeting, we joined forces with Environmental Investigation Agency (EIA), OceanCare and Humane Society International (HSI) and asked the European Union to present the case for making plastic pollution a priority concern for the IWC and to push for regional and international cooperation to tackle its impacts on whales and dolphins.

We wrote a briefing for government delegates, and my WDC colleagues worked hard at the meeting itself to bring the issue to their attention.

Our WDC team at the IWC meeting 2022
Our WDC team at the IWC meeting 2022

Tremendous success

In the end, a slightly edited version of the draft text was adopted by consensus by the member nations of the IWC. This is an amazing achievement for us, because ‘by consensus’ means that all commission members voted for it unanimously, which doesn’t happen very often at IWC meetings.

By setting out a clear plan, including supporting and engaging with discussions on a new global agreement on plastic pollution, the IWC can have a massive, positive impact on global efforts to reduce plastic pollution and reduce the harm it’s doing to whales and dolphins.

It’s a huge problem, but we won’t be daunted by it – we can solve the problem if enough politicians want to. With your support, we’ll keep this largely unseen menace visible, and keep up the pressure on those who have the power to help.

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