What is whale fall?
When a whale's life ends, another story is just beginning.
When a whale’s life ends,
when their body descends
into the deep and dim abyss,
when the sunken life sinks
to the ocean's base brink,
there’s a bounty land-dwellers will miss.
A feast for sleepers, blind creatures, deep-eaters
and the like who emerge from the silt,
in vivid animation of aquatic creation,
welcoming all those who gorge to the hilt.
When a whale’s life ends,
when their body descends
and their final song has been sung.
It’s no sorry tale
to say goodbye to the whale,
as new life has just begun.
What is a whale fall?
Whales are the makers of a healthy ocean. Their poo fertilises the carbon-offsetting phytoplankton, which are key to fighting climate change. They spread essential nutrients on their migratory journeys around the world, feeding microorganisms and sustaining marine ecosystems as they go. Even in death whales remain fundamental.
Referred to as ‘whale fall’, when a whale dies and falls to the ocean floor, it provides a literal body of nutrients for the deep sea inhabitants. We don’t often think about what happens when a marine animal dies and why would we. I suspect, as they’re swimming along in the middle of the ocean one day, old age (hopefully, and not some larger fishy) swims up beside them and that’s that. A true whale fall only occurs when the carcass has sunk to the bathyal or abyssal zones. Bathyal, also known as the midnight zone, is somewhere between 1000 to 4000 metres below the ocean surface, and the abyssal zones, where life is lived in perpetual darkness, is anywhere between 4000 to 6000 metres below the ocean surface. I think I’ll stay floating on a Lilo at the surface, thank you.
The conditions of these deepwater regions are ideal for a slow decomposition process and there are usually fewer scavengers in the water column here. This means the carcass can reach the deep-sea intact. In coastal oceans, the high rate of predators in the warmer waters quickens the decomposition process, and if decompositional gases are keeping the carcass afloat then those higher up in the water column will have their feast before those on the ocean floor even know about it. Left with the scraps of the skeleton, which are still nutritious for some organisms, but a fully formed ecosystem has lost its opportunity to grow.
Fortunately, the cold temperatures significantly slow the rate of decomposition and high hydrostatic pressure increases gas solubility. Based on these perfect conditions, it’s no surprise that scientists have estimated a whopping 690,000 carcasses or skeletons of the nine largest whale species are in one of the four stages of decomposition at any one time.
The four stages of whale fall decomposition
Stage 1
Speedy scavengers are first in line at the buffet, consuming the soft tissue including the much sought after fat stores. Hagfish and sleeper sharks are among those who build the foundations of a blossoming blue ecosystem and though they’re quick off the mark, this stage can last for as long as 18 months.
Stage 2
Dubbed the “enrichment opportunists’”, those introduced in Act II Scene I prefer to seize the bones and the surrounding nutrient-rich sediment or any other remaining detritus that’s up for grabs. Worms, crustaceans, mollusks and other critters will gorge themselves for around five years in this second stage of decomposition. A long second course!
Stage 3
Whale bones are rich in lipids so when bacteria breaks down these fatty composites it nourishes deep sea shellfish like mussels, clams, limpets and sea snails. The lipids make up 4-6% of the whales body weight which means this stage can last for up to 100 years. The term ‘all you can eat’ was coined here in stage 3.
Stage 4
Research posits a fourth stage of decomposition from the whale fall, known as the ‘reef stage’. When only minerals remain in the bones and all other organic matter is gone, filter feeders find themselves with the perfect hard substrate to rest on for some fine dining. But we don’t know for sure if this dessert course is actually served.
How this benefits the ocean.
A whale’s carcass is a true harbinger of deepwater creatures as it creates, sustains, and connects ecosystems of over 200 species. This concentrated food source can support a rich community of life under the sea for almost a century – a biodiversity phenomenon. Whale falls keep the oceans flourishing by providing evolutionary stepping stones for multiple lineages to move and adapt to new environmentally-challenging habitats. By ‘environmentally-challenging’ I mean climate change of course. Although I’m certainly not suggesting we should take it lying down, it is important that those in the deep ocean figure out how to adapt to the coming change by witnessing and experiencing the effects occurring at the surface. The deep ocean will already be aware of the unnatural variance through the likes of whale fall. The intuition of animals and nature is unbelievable.
How it benefits us all.
The depletion of large whales (and therefore a reduction in whale falls) by the whaling industry is believed to have cost the deep ocean a total biomass loss of 30%. This means the massive amounts of carbon that would have otherwise been stored in the deep ocean in the event of a whale fall, is also at a loss. Whales help to sequester carbon throughout their lives, but in a single whale fall around two tonnes of carbon (in relation to a 40-tonne carcass) can be locked away for hundreds or thousands of years. By other means, this would take almost 200 years for the same amount of carbon to reach the abyssal zone, and it would take thousands of trees to reach an equivalent in carbon sequestering. In just one Californian marine sanctuary, whale fall accounts for 60% of their annual carbon sequestration.
This is the benefit of whale fall.
As I write Beached each week, I often wonder if there is anything that whales do which doesn’t benefit either us, or one of their oceanic acquaintances. Their innocent and oblivious acts; pooing at the surface, travelling vast distances with key nutrients on their back, or even just cordially waving to our tour boats and allowing their inquisitive babies to get a closer look, are all blessings. Whales do more good than they could ever know.
When a whale's life ends, another story begins. That is the wonder of the whale. Their natural behaviour which keeps the world turning.
Save the whales. Save the world.
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Amie 🐋