When dead whales wash up on dry land they provide a vital food source for many species, but fewer whales means fewer carcasses and that's bad news.
It may seem strange to talk about the benefit of dead whales, but even in death whales are a vital part of healthy ecosystems, and not just marine ecosystems, but coastal ones too.
When whale bodies sink to the sea floor, as a ‘whale fall’, they provide food and a habitat for hundreds of species, from sharks to bone-eating (or zombie) worms, some of which are only found on whale carcasses. What fascinates me is that recent studies are showing that dead whales, dolphins, and porpoises that wash up on the shore are also an integral part of coastal ecosystems, and for scavenging species in particular.
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The nutrients from their bodies provide an important food source to animals including crabs, mammals and birds, which come from a wide area just to feed on a whale carcass.
Polar bears scavenge on stranded whale carcasses as they provide fat and protein-rich food to help them cope with extensive periods of fasting. Amazingly, one stranded whale carcass can provide food for up to a year, and a bowhead whale carcass is the nutritional equivalent to around 1,300 ringed seals.
Polar bears need sea ice to hunt their main prey of seals. But as our planet warms, impacting how much sea ice there is, how far it extends and how long it stays frozen before it thaws, stranded whale carcasses provide an alternative food source for hungry polar bears adapting to climate change.
The massive reduction in whale populations due to commercial whaling, combined with the removal of whale carcasses when they wash up on shores, has led to a significant reduction in the abundance of dead whales on beaches. This has a direct impact on the species that depend on them, such as Californian and Andean condors. Populations of these condors have dramatically declined, and their foraging behaviour has changed because of the loss of whale carcasses.
Andean condors in Patagonia, used to feed extensively on stranded whale carcasses. However, the current scarcity of washed-up dead whales has meant they have had to switch their diets to land mammals. They are now forced to travel huge distances from their nesting sites close to the sea, sometimes across mountain ranges, to find food.
It is not just the fat from a dead whale as a direct food source that is important for coastal scavengers. Just as with dead whales on the ocean floor, whale carcasses on land increase the nutrients in the soil and sediment where they lie, and there are host of terrestrial species that specialise in consuming meat and bones. A study of a stranded minke whale carcass documented 57 different beetle species as specialists in eating meat and bones, and 12 of these were new species to the area.
Whale carcasses are usually removed over concerns of odour and safety and transported to landfill or incinerated or buried. Where possible it would be beneficial to consider leaving a carcass where it washes up, especially in more remote areas, or moving a carcass or closing an area of beach where the abundance of scavengers can be left to quickly strip the carcass.
The more we learn about whales and dolphins, the more we understand how these awesome beings are integral to life on Earth. We must protect them because they have the right to live free from human harm, but also because we need them.
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