Whale fall is the term used for a whale carcass that has fallen to the ocean floor. When a whale dies in shallow water, its carcass is typically devoured by scavengers over a relatively short period of time—within several months. The carcass can provide sustenance for a complex localized ecosystem over periods of decades. Many whales die when female whales or newborns, stressed by the process of birth, make their annual migration.
In 1987, a manned submersible called Alvin was making a routine dive along the muddy plains of the deep sea when its pilot spotted what he thought was the fossilized remains of a dinosaur. Instead of an exotic underwater beast, it turned out to be the 21-metre-long skeleton of a blue whale. Just as windfalls deliver a sudden bounty of ripened fruit, whale falls see the death of a whale bring a host of nutrients to the sea floor.
The falls are few and far between, and difficult to track and study, but researchers are learning ever more — sometimes through extreme measures — about the new species to be found among the remains.
Scientists now estimate that a whale-fall community can survive for up to a century by sucking the fats and sulphides from these bones. In fact, one cadaver offers the same amount of nutrients that normally sinks from the surface to the sea floor in 2000 years, and this is of great benefit to innumerable species.
Dr Craig Smith:
For almost 20 years, Craig Smith, a biological oceanographer at the University of Hawaii, has studied whale carcasses after they have sunk to the seafloor. Such research has unveiled a number of strange creatures. The prize find so far is a newly described worm genus, Osedax2 — Latin for 'bone-devourer'. With no mouth, stomach or eyes, Osedax has evolved a root system to excavate the fat out of whale bones. Osedax evolved roughly 40 million years ago, about the same time scientists believe many whale species arose.
Whaling is threatening newly-discovered deep-sea creatures with extinction, according to research by Craig Smith. He is sounding the alarm that whaling continues to be a threat to these ecosystems. His research, based on models and reported last week at the Deep-Sea Biology Symposium in England, suggests that extinctions may have already occurred in the North Atlantic where 13 species of great whales were decimated in the 1800s. Extinction may also be ongoing in the Southern Ocean, where intense whaling persisted until the 1970s.
One whale fall can provide up to 160 tons of organic material, as much as thousands of years of marine snow, the organic debris that drifts down from surface waters.
'The possibility that whaling has caused species extinctions at the remote deep-sea floor gives us new appreciation for the scale of human impacts on the ocean,' said Smith. 'We must recognise that the oceans consist of a group of tightly connected ecosystems – over-fishing or pollution in surface waters is bound to cause problems hundreds of metres below.'
Smith estimates that about one-third of whale fall specialists may have already been wiped out. “Removal of whales from the ocean will cause the extinction not only of whales, but likely dozens to possibly hundreds of deep-sea species that appear to rely on whale fall communities to complete their life cycle,” explains Smith.
As exotic and diverse as whale fall communities are proving to be, whaling in the 1800s and 1900s may have drastically reduced the number of carcasses that sank. “The decimation of whales during the last century also has consequences for an entire community of decomposer animals that live at the bottom of the ocean,” says Monterey Bay Aquarium evolutionary biologist Bob Vrijenhoek.
Whale populations and commercial whaling:
After many hundreds of years of unregulated commercial whaling some whale populations were so depleted - such as that of the blue whale, which has never recovered - that they were at serious risk of extinction. Whale populations have not sufficiently recovered enough to sustain hunting, especially given the other threats they currently face.
Threats to whales:
These threats include toxic pollutants such as DDT, dioxins, PCBs (organochlorines used in industry) and mercury. They suffer from deadly high intensity sounds produced by military sonar and air guns, and by-catch, with some 300,000 dolphins and whales drowned every year after they become entangled in fishing nets or other fishing gear.
There is also over-fishing of prey species, ship strikes, climate change affecting habitat, migration routes and prey species availability and habitat destruction. The threats on the oceans today are increasing.
Destruction of marine ecosystems:
“The systematic destruction of the great whales was a stupendous act of modern ecological folly...” Jeremy Jackson of Scripps Institution of Oceanography in San Diego writes in a recent paper in Whales, Whaling and Ocean Ecosystems. He argues that the new findings on the past profusion of whales show our conventional view of marine food chains is upside down. Modern oceans are dominated by small and lowly creatures. They comprise most of the biomass, with larger species further up the food chain comprising ever less biomass. Jackson offers a startling new picture of life on Earth, a world in which giants ruled, and ruled in huge numbers. And if Jackson is right, then even the most “recovered” of today’s whale populations are only a tiny fraction of their former numbers.
In 1998 a group of scientists published a study about the impact of whaling on the environment. The study showed that a 1% change in the diet of killer whales was enough to cause significant declines in marine mammal populations. In the last 30 years, the population of sea lions has decreased by over 80 percent.
Whales began to eat sea lions when the seal population declined. Once sea lions became rare, sea otters became a part of the whales' diet.
Whales the scapegoats:
The whaling countries, Japan, Iceland and Norway increasingly argue that whales need to be culled to protect fisheries. What is certain is that marine mammals like whales and seals make convenient and profitable scapegoats, when in fact; it is human over-fishing and other destructive fisheries practices, and their impact on commercial fish stocks, which need to be curtailed.
photo: Antarctic Krill - under threat.
There is growing evidence that global climate change has led to a reduction of ice algae, the main food source of krill. When the ice forms too late the production lessens impacting on zooplankton populations like krill that graze under the ice surface on ice algae. ”The ice edge is an absolutely critical habitat, a nursery for larval krill.” says Scott Gallager, a marine biologist at Woods Hole Oceanographic Institution (Woods Hole, Massachusetts, United States).
Krill is believed to be a key factor in the reproductive success rate of the whales but a deep understanding of their role and affect on predator populations when climate temperatures rise has yet to be understood.
The resumption of whaling may not necessarily be an option anymore. Recent scientific researches have revealed that whaling is not ‘harvesting a sustainable resource.’ There is no such thing as sustainable whaling.