A new study, published today in Nature Communications confirms what researchers have long suspected: Whales transport their urine, placentas and skin – a potent tonic loaded with nutrients – the longest known distances and thereby help keep the ocean and its diverse ecosystems healthy.

This incredible tonic for the ocean consists of deposits of whale urine, placentas, carcasses, and sloughing skin. While it is generated in the whales’ summer feeding habitats, it is then transported through the ocean as the whales travel on their long journeys to winter breeding grounds.

The new study, partly funded by the marine charity Whale and Dolphin Conservation with an international research team, highlights that this process of moving essential nutrients like nitrogen from high-latitude polar areas like Alaska and Antarctica to low-nutrient tropical grounds like Hawaii and the Caribbean is the longest known transport of nourishment by mammals on the planet.

The researchers found that humpback, gray, and right whales transport more than 4,000 tonnes of nutrients such as nitrogen to low-nutrient coastal areas in the tropics and subtropics, many of which have coral reef ecosystems each year – a number roughly comparable to gardeners spreading about 2 million bags of fertiliser on their roses. They also bring more than 45,000 tonnes of biomass.

The study further established that whales bring more nitrogen from their feeding grounds than the ocean’s natural processes such as ocean currents and upwellings provide, significantly boosting marine life. This nutrient input helps fuel phytoplankton growth which is critical for the marine food web.

Ed Goodall, from the policy team at Whale and Dolphin Conservation who worked with the study author, told Oceanographic: “The reduction in whale numbers by commercial whaling and multiple pressures that they suffer from today means the ocean has lost is delivery drivers, moving things from one place to another.

“By moving nutrients around the planet – just as bees pick up and move pollen – whales help keep the ocean functioning just like pollinators do on land. If we restore their numbers and the processes which they deliver, like the great whale conveyor belt, the ocean will be healthier, more abundant and importantly, resilient in the face of climate change.”

“If plants and phytoplankton are the planet’s lungs, taking in carbon dioxide and expelling oxygen, then whales and other animals are like the circulatory system,” added report author and whale expert, Joe Roman. “Known as the great whale conveyer belt, this movement of nutrients through the ocean can have a big impact on marine ecosystems.”

To showcase the scale of this large ‘conveyor belt’, the study highlights an incredible example: While pregnant North Pacific humpback whales gain about 14kg per day eating herring and krill in summer, they burn almost 100kg per day while they are nursing on the breeding grounds. As they burn up their energy reserves, they release nitrogen and other elements in their urine. Previous research in Iceland suggests that fin whales produce more than 250 gallons – about 974 litres of urine – per day when they are feeding, whilst humans pee about 2 litres per day (less than half a gallon).

As whale populations were greatly reduced by commercial whaling in the past centuries, this ‘conveyor belt’ is much smaller than it was historically, though it has recovered in some areas thanks to the banning of the commercial hunt throughout much of the world’s oceans.

While the study argues that these numbers might have been three times higher before commercial whaling, it further strengthens the argument for the protection of these remarkable species. 

Click here for more from the Oceanographic Newsroom.