The Complete Disaster That Is Industrial Whaling

In the 20th century, the largest animals that have ever existed on Earth almost stopped existing at all, thanks to humans.
Blue whales, humpback whales and other baleen whales had long been hunted, but as whaling became industrial, hunts that might have taken a single whale before suddenly became massacres. Using explosive-tipped harpoons that were fired from cannons and factory ships that could process carcasses at sea, whalers slaughtered vast numbers of whales for their oil, which was used to light lamps, lubricate cars, and make margarine.
Prior to this, blue whales numbered over 360,000. In just sixty years, which is roughly the life span of a blue whale, humans took the blue whale population down to just 1,000.
In a single century, whalers killed at least two million baleen whales, which together weighed twice as much as all the wild mammals on Earth today. 
That is quite an appalling achievement, even for humans.

And all of those missing whales left behind an enormous amount of uneaten food. 
Scientists have estimated that prior to industrial whaling, the whales would have consumed about 430 million metric tons of krill - small, shrimplike animals - every year. That’s twice as much as all the krill that now exist and twice as much by weight as all the fish that today’s fisheries catch annually.
And you would have thought krill would have flourished in the absence of the top predator in the food chain. But no, their numbers actually plummeted too!!
Whales, despite their size and the amount of food they ate, didn’t deplete the oceans in the way that humans now do. When the whales were killed, the food chain collapsed from the bottom, turning seas that were once rich with life into marine deserts.

But why did this happen? Well, the answer lies in a mineral vital to all life - iron.
The North Atlantic gets a good supply of iron in dust blown from the Sahara desert, but the southern oceans have a lot of land covered by ice so don’t get “fertilised” this way.
But organisms like krill contain lots of iron, and when they were eaten by the whales, the iron was released into the water in the whales’ faeces, so seeding the food chain by feeding plankton, which then fed krill and fish, and then was returned to the whales when the krill and fish were eaten so the cycle could start again.
So removing almost all whales also removed the source of the southern oceans’ fertiliser and the food chain virtually collapsed.
As has also happened on land, the marine ecosystem was beautifully balanced with it actually being supported by the top predator, until humans upset the balance.

There are now plans to carefully seed parts of the southern oceans with iron in an attempt to recreate the whale fertilisation effect. This should allow more plankton to bloom, which will have the added benefit of taking in carbon dioxide from the air. The plankton will then feed more krill and hopefully, encourage more whales into the area, who will then take on their natural role of fertilisation of the waters and supporting the food chain as their numbers grow. The whale effect would also increase the fish populations, aiding many species like penguins and seals, as well as the whales, to also increase their populations, thereby healing some of the manmade damage.
Whaling almost destroyed a whole and very important food chain that also affects us.
It is ironic that some who still hunt whales accuse them of depleting the oceans to the detriment of humans, and that their numbers need to be controlled, when actually, it is the other way around!!