- When marine mammals wash ashore, government agencies often set about removing the carcass.
- Strategies include burying the body, transporting it to a landfill or incinerator, towing it out to sea, and in at least one misguided case, detonating it.
- But in removing dead, stranded cetaceans from beaches, we may be overlooking the environmental benefits they offer, according to a new study.
- The researchers recommend leaving carcasses to rot in place whenever possible, where the environmental benefits they offer include supporting communities of scavengers, such as threatened species like polar bears and California condors.
What happens when there’s a dead whale on the beach?
In many reported strandings, the next steps look quite similar: where possible, biologists and veterinarians examine the carcass and conduct a necropsy to try and figure out why the mammal may have died. Then, government agencies set about removing the carcass from the beach. In 1970, one infamous removal plan involved blowing up a 14-meter-long (45-foot) sperm whale (Physeter macrocephalus) in Oregon, U.S., with half a ton of dynamite because it was too big to be hauled away. The result: large chunks of whale flesh rained down on curious bystanders and crushed a car.
But in removing dead, stranded cetaceans like whales, dolphins and porpoises from beaches, we may be overlooking the several environmental benefits they offer, according to a study recently published in the journal Ecosystem Services.
Human societies historically viewed cetacean carcasses that washed ashore as important sources of food or as conduits for cultural and scientific knowledge — not as nuisances that must be removed, the study found. These benefits should prompt us to rethink how we manage beached carcasses today, Martina Quaggiotto, an ecologist at the University of Stirling, U.K., and lead author of the study, and her colleagues, argue.
“Whale strandings have been the focus of wonder and awe for hundreds of years,” Joe Roman, a conservation biologist at the University of Vermont and author of the book Whale, who was not involved in the study, said in an email. “Quaggiotto’s work helps recenter our view of these carcasses, looking at them as benefits and bounties rather than problems to be disposed of as quickly as possible.”
Benefits for our ancestors
Cetacean strandings are hardly a new phenomenon. “Strandings have always been there, and humans have always been in contact with strandings,” Quaggiotto said on a call. “And so we started thinking about what were the value of these strandings for humans in the past.”
The researchers reviewed available peer-reviewed literature on how humans historically interacted with stranded cetaceans, and found 27 studies describing a range of interactions. Archaeological evidence from Spain, for example, suggests that human ancestors consumed the meat of stranded whales in prehistoric times. Historically, Indigenous peoples, including the Inuit living in the Arctic, salvaged meat, bones and other parts from stranded carcasses. Certain groups, such as the Fuegians of the Patagonian coast, and the Māori in New Zealand, held cetacean strandings in high regard, viewing them as bounties offered by nature to be shared with the communities.
Other cultures evolved different views. Since the 11th century, stranded cetaceans on English coasts came to be called “royal fish,” their meat kept only for the wealthy and their bones used to make art, the study found. From the 18th century, stranded carcasses became more of a scientific fascination, with naturalists describing new species based on stranded individuals, and researchers today studying stranded cetaceans to understand ocean health and how human activities may be impacting the animals.
“So we moved from provisioning ecosystem services to cultural and scientific ones. These are the ones that are most visible in our literature research through time,” Quaggiotto said.
Ecological benefits
Benefits to people past and present aside, stranded marine carcasses are crucial for many wildlife communities, the study’s authors argue. In the ocean, “whale falls,” or carcasses of big whales that come to rest on the seafloor, support huge communities of scavengers including various fish, sharks and worms. These falls also provide generous offerings of nutrients for deep-sea communities. And they carry tons of carbon in their massive bodies, down to the depths and safely away from Earth’s atmosphere.
Like whale falls, decomposing stranded mammals can enrich the coastal environment with nutrients. Moreover, the study notes, threatened wildlife like polar bears (Ursus maritimus) often feast on stranded whales and other cetaceans, stockpiling the necessary fat and protein to endure extended periods of fasting. In warmer climes, animals like brown bears, wolves and foxes also feed on marine mammal remains.
In the past, stranded carcasses have been vital for obligate scavengers like the critically endangered California condor (Gymnogyps californianus), which subsisted largely on dead, washed-ashore marine mammals. But human activities like whaling reduced numbers of marine mammals and their strandings, and forced the condors to shift to terrestrial carcasses, the authors write. However, these were frequently riddled with bullets, poisoning the birds with lead.
If stranded cetaceans are important for human and ecosystem well-being, how should people manage a stranded carcass?
How to manage a carcass
Many countries have regulations that tell wildlife agencies or local governments and organizations what to do when there’s a dead cetacean on the beach. Quaggiotto and her colleagues dug into the carcass-management regulations of 23 countries and regions and found great variation.
For example, in New Zealand about 39% of carcasses are left on site to naturally decompose, while 38% are buried, according to the study. Indigenous people, such as the Māori, are often involved in the carcass-management process. In a stranding this month of more than 30 pilot whales in New Zealand, for example, members of a Māori organization blessed the dead cetaceans, which remained in a secured area to decompose naturally.
Similarly, in the U.S., some 28% of carcasses are left on site, while 21% are buried, the study found. The third most common method in the country is to transport the carcasses to landfills; there is also a move toward composting marine mammal bodies. In European countries, like Belgium and France, which have numerous strandings, regulations favor complete removal and destruction of carcasses, the study notes, usually at landfills or incineration plants.
The researchers compared all of the frequently used methods for managing stranded cetacean carcasses, and found that leaving a carcass where it lies to decompose naturally offers the greatest ecological benefits, from supporting scavengers to enhancing soil and water nutrients. It also costs the least. You don’t need big machinery, there’s no transportation involved, and the expenses are low, Quaggiotto said.
Burying a carcass is also a good strategy, the authors note, but it is laborious and expensive. Similarly, while composting can enhance soil nutrients and break down contaminants and pollutants, the transportation is costly. Towing the carcass out to sea is also a good method because it allows the corpse to decompose naturally in water. But it requires a towing boat, and risks the carcass floating back to the coast, Quaggiotto said.
Strategies like transporting the remains to landfills and incineration plants are the least beneficial and have the highest economic, logistical and environmental costs, according to the study.
“You need to lift the carcass and move it in a truck. In all this transport, we are actually releasing carbon dioxide,” Quaggiotto said. “In the incineration plant, too, there’s carbon dioxide emission.”
The researchers recommend leaving carcasses in place whenever possible, but they also acknowledge that this strategy could have undesirable social impacts. For example, rotting carcasses can attract sharks and feral dogs to the beach. Then there is the awful stench of rot. It can take from a few months to a few years for big carcasses to decompose completely on a beach; how long depends on factors such as the kinds of scavengers around and the temperature, rainfall and moisture, Quaggiotto said.
“So our paper is not saying that whenever there is a carcass, leave it there,” Quaggiotto said. “We are not saying close the beach for three years because there’s a whale carcass decomposing. What we are saying is try and find a compromise. If it’s in a remote beach and the locals are OK with it, let’s leave the carcass there to decompose. If it’s a small carcass on a busy beach, then maybe we can move it to a more remote beach where it can decompose and we can let nature play out.”
In certain situations, though, it’s better to remove the carcasses — such as when authorities use chemicals to euthanize beached animals, because these could threaten scavenging wildlife communities.
“In the future, [the] number of strandings could increase not only because of climate change but also because populations of whales are recovering after the whaling era,” Quaggiotto said. “So how much will you spend trying to get rid of these carcasses because of mass mortality events?”
Roman agreed with the study’s authors that whale carcasses should be left to naturally compose whenever possible. “Whales provide enormous impulses of marine resources to terrestrial systems when they strand,” he said. “Rather than simply disposing of them, Quaggiotto and colleagues make a good case for measuring and protecting the many services they provide.”
Banner image: A bloated humpback whale on a beach in California, U.S. Image by docentjoyce via Flickr (CC BY 2.0).
Citation:
Quaggiotto, M., Sánchez-Zapata, J. A., Bailey, D. M., Payo-Payo, A., Navarro, J., Brownlow, A., … Moleón, M. (2022). Past, present and future of the ecosystem services provided by cetacean carcasses. Ecosystem Services, 54, 101406. doi:10.1016/j.ecoser.2022.101406
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