Most people would easily agree that peeing in a swimming pool is unsanitary. But people think nothing of swimming in lakes, rivers, and oceans, where many animal species do that (and more). Pee (urine) is a bodily waste product, something the body doesn't need anymore and that can cause problems if retained. But it can also be useful in environmental settings.
Whales are the largest animal creature in the seas and world. The fin whale, second largest in the world at 18–27 m (60–90 ft) long, can put 946 liters (250 gallons) of pee into the ocean in a single day. The third largest whale, the sei whale (19.5 m or 64 ft long) excretes 522 liters (138 gallons) per day.
A fin whale and comparison to a human in size (Wikipedia)
A sei whale compared to human (Azores whale watching)
The ocean is far larger than any swimming pool, so you might think even this much urine is still a drop in the bucket. You'd be correct. Estimates put the population of sei whales at 50,000-80,000, and fin whales comprise about 100,000-119,000. Compare that volumetric contribution of urine to the 321 million cubic miles of ocean water.
Researchers from the UK and US have learned that gray, humpback, and right whales do not eat or defecate during their breeding season, but they still urinate. For example, in summer humpback whales feed along the shores of the Alaskan coast, but in winter they travel to warmer waters near Hawaii to breed. They have accumulated thick layers of fat (blubber) in summer, and as it is digested in the winter breeding season, the blubber is broken down into urine. A key chemical component of urine is the nitrogen-rich urea.
Location of humpbacks during feeding and breeding seasons (Science News Explores)
Professor Joe Roman (University of Vermont) and his colleagues from Arizona, California, Florida, New Jersey, the UK, Brazil, and Denmark published a study in March 2025 regarding how baleen whales transport nutrients from their feeding grounds to tropical and subtropical ecosystems where they breed. Ocean creatures like zooplankton float in the waters as the currents take them wherever they drift.
Types of zooplankton (Wikipedia):
copepods (1–5), gastropod larva (6) doliolids (7), fish eggs (8), and decapod larva (9)
Their wastes and dead bodies fall slowly from all levels of the ocean to the seafloor in what is called marine snow.
From YouTube
But whales feed mostly on the bottom, so the nutrients there get recycled only when whales come to the surface to pee or poop. It may have something to do with the different pressure and temperature causing the body to release its waste. This process of bringing such elements to the surface is called the whale pump.
The whale pump distribution of ocean bottom nutrients (Roman and McCarthy, 2010; Roman et al., 2014)
So, the nitrogen and phosphorus in whale wastes mix with the upper ocean layers and serve to feed zooplankton and other organisms. Roman and his colleagues studied baleen whales (gray, blue, humpback, and fin whales) to see how much they contribute to the ecosystem from their wastes, rotting carcasses, and ejected placenta. As mentioned earlier, they found that one fin whale alone can excrete 1,136 liters (250 gallons) of urine per day. “In a place like Hawaii, the whales are bringing in more nitrogen than is being transported by wind and currents,” Roman said. From urine, feces, rotting bodies, and placenta, those whales dump 3,784 tons of nitrogen and 46,512 tons of organic matter into their breeding grounds, and most of the nitrogen in it comes from the urine.
Humpback whale peeing (from YouTube)
Getting back to urea, the major component of urine, it looks like this chemically. It has 2 ammonia groups attached to carbon and oxygen.
From Wikipedia
While zooplankton are the animal portion of plankton, phytoplankton represent the microscopic plant portion. These absorb urea in ocean waters and break it down into ammonia and carbon dioxide, which are building blocks of amino acids and proteins. As phytoplankton and zooplankton feed and grow, they circulate in the ocean as marine snow, as well as serve as food sources for other sea creatures. So, whale urine fertilizes the ocean. And the blue-green algae component of phytoplankton is also important in absorbing carbon dioxide from the atmosphere, an element of climate change balance.
Phosphate ions are also in urine, and in greater amounts in feces, and the phosphorus in those ions are needed by the local plankton to make DNA, RNA, phospholipids in cell membranes, and ATP (an energy source for cells). Here are examples of just how much of each is excreted relatively in whale feces, as well as other macronutrients.
Data from Freitas, et al., 2025
Whales do not find food and breeding grounds in the same places in the world, which is a good thing for spreading around their pee nutrients. Here is a map of just 3 species showing where they live.
Figure adapted from Roman et al., 2025
A 2015 study by Professor Christopher Doughty and his team (including Joe Roman) from various countries investigated the contribution of body wastes by whales and other animals over time. With regard to whales, they found that since whaling became an industry, the "whale pump" effects have dropped by about 70%, so fewer nutrients are now spread in the oceans.
