Whales in a Sea of Plastic: How Microplastic Pollution is Harming Whales

Brealin Maya

Whales are among the largest animals ever to live on Earth. They help regulate marine ecosystems, store enormous amounts of carbon, and in doing so, contribute to slowing climate change throughout their lifetimes (WWF). Despite their immense size, these ocean giants face a surprisingly tiny but growing threat: microplastics. These plastic particles, measuring less than five millimeters across, now pollute every ocean on Earth. Scientists are discovering that whales are swallowing millions of these particles every day, raising serious concerns about their long-term health (Stanford Report). Unlike larger pieces of plastic that can become lodged in a whale's stomach, microplastics are nearly impossible to avoid. Recent research reveals four major ways these tiny pollutants are harming whales.

The first major way in which microplastics are harming whales is while they are feeding. Filter-feeding whales are especially vulnerable because of how they eat. Blue, fin, and humpback whales take massive gulps of seawater filled with krill and small fish, then strain out their prey using baleen plates. Unfortunately, the same feeding strategy also captures microplastics. A Stanford University study estimated that blue whales may ingest up to 10 million microplastic particles every day, while fin whales consume between 3 and 10 million particles daily. Humpback whales feeding primarily on krill may ingest more than 1 million particles each day (Stanford Report). Surprisingly, researchers found that most of these plastics are not swallowed directly from seawater. Instead, whales ingest them through their prey, which has already accumulated microplastics. As krill and small fish consume plastic, those particles move up the food chain until they reach some of the ocean's largest predators (Stanford Report). This means whales are exposed to plastic pollution every time they feed, making avoidance nearly impossible.

The second concern regarding microplastics and whales is that microplastics may reduce the nutritional value of whales’ food. Scientists are also concerned that microplastics may indirectly harm whales by affecting the prey they depend on. Laboratory studies suggest that krill and small fish can mistake plastic particles for food, filling their stomachs without receiving adequate nutrition. Researchers speculate that prey containing microplastics may become less energy-rich, meaning whales must consume even greater quantities of food to meet their enormous energy demands (Stanford Report). As one Stanford researcher explained, it is similar to "training for a marathon and eating only jelly beans"—the stomach may feel full, but the body receives far less nourishment (Stanford Report). Because whales require tremendous amounts of energy for migration, reproduction, and raising calves, even small reductions in food quality could have significant long-term consequences for their health and survival.

The third cause for alarm is the recent discoveries that microplastics do not always pass harmlessly through a whale's digestive system. In 2023, researchers at Duke University found microscopic plastic particles embedded in the lungs, blubber, and other tissues of stranded whales and dolphins. This suggests that some plastics move beyond the digestive tract and become lodged inside the body (Duke Today). Scientists are still investigating exactly what these embedded plastics do, but they worry they may cause inflammation, physically damage tissues, or expose whales to chemicals associated with plastics. Some plastic compounds are known to interfere with hormones and act as endocrine disruptors in other animals (Duke Today). Although researchers emphasize that much remains unknown, the discovery demonstrates that plastic pollution is affecting whales on a deeper biological level than previously understood.

Finally, the last major concern regarding microplastics and whales is that microplastic pollution is no longer confined to heavily populated coastlines and has reached even the world's most remote whale populations. Researchers studying beluga whales in Canada's Eastern Beaufort Sea—a remote Arctic region—detected microplastics in the gastrointestinal tract of every whale examined (Moore et al.). Individual whales were estimated to contain between 18 and 147 microplastic particles, despite living thousands of miles from major urban centers (Moore et al.). This finding highlights how widespread plastic pollution has become. Ocean currents transport plastic across the globe, while tiny fibers shed from synthetic clothing and other consumer products circulate through marine food webs. Even whales living in relatively pristine environments can no longer escape exposure (Moore et al.).

While many questions remain about the long-term effects of microplastics, scientists agree that whales are serving as powerful indicators of the health of our oceans. Their enormous feeding requirements, long lifespans, and position at the top of marine food webs make them especially vulnerable to accumulating plastic pollution. Reducing single-use plastics, improving waste management systems, limiting microfiber pollution from textiles, and supporting international efforts to reduce plastic entering the oceans are all important steps toward protecting whales and the ecosystems they help sustain (WWF). Every piece of plastic prevented from entering the ocean is one less piece that can eventually make its way into the food chain—and into the bodies of these magnificent animals.

Citations

Bates, Karl. “Marine Lab Study Finds Microplastics Embedded in Tissues of Whales and Dolphins.” Duke Today, 10 Aug. 2023, today.duke.edu/2023/08/marine-lab-study-finds-microplastics-embedded-tissues- whales-and-dolphins.

Garthwaite, Josie. “Whales Eat Colossal Amounts of Microplastics | Stanford Report.” Stanford Report , 1 Nov. 2022, news.stanford.edu/stories/2022/11/whales-eat-colossal-amounts-microplastics.

Johnson, Chris. “Whales and the Plastics Problem | WWF.” WWF, 18 Feb. 2021, www.worldwildlife.org/news/stories/whales-and-the-plastics-problem/.

Moore, R.C., et al. “Microplastics in Beluga Whales (Delphinapterus Leucas) from the Eastern Beaufort Sea - Sciencedirect.” Science Direct , Jan. 2020, www.sciencedirect.com/science/article/abs/pii/S0025326X19308793.

Naddaf, Rachelle. “Five Animals Impacted by Plastic Pollution and How You Can Help Protect Them.” Oceana Canada, 6 July 2022, oceana.ca/en/blog/five-animals-impacted-plastic-pollution-and-how-you-can-help-protect -them/.