So, how can you possibly farm with no hands, or plant crops in an ocean? In the sea, you can’t, even mark out a patch of water to call your own, so there is no point in trying to hold it nor demanding from others the sole right to harvest the fruits of your labours. Ocean farming might seem impossible to us, but such individualistic thinking is borne of our landlubbing past. Living in the ocean seems to induce a more collectivist way of living. Given that, the answer to the question is simple – they farm by diving deep to selectively hunt iron rich species, and subsequently defecating only at the surface.
This mechanism provides the surface layers over the benthic zone with their missing minerals. Photosynthetic algae are then able to grow profusely, and fuel the entire ecosystem. Sperm whales can only gain benefit for their species as a whole. The benefit of their endeavour falls to all other ocean life also.
Our default assumption should always be that this is not farming per se, and purely an accident of nature. It is often written that sperm whales like the taste of squid, and, it seems, they really do have have to dive down round half a kilometer or so to find a good supply of them. An obvious counterargument to the ‘by accident’ hypothesis is that the huge energy expenditure of such deep diving should render the exercise inefficient, and that first sperm whale with mutant squid-hating taste buds would have such an evolutionary advantage over the others that its descendants would come to dominate the population in no time.
However that counterargument is not sufficient in itself. What if sperm whales are so specialised to catch and digest squid, that a change of diet would present more difficulties than it solved? I find one mighty difficulty with believing that: data from the first sperm whaling era. It shows fish-filled stomachs were more common than squid filled ones in that era. I am unsure, though, of what proportion of these were deep sea fish. I would be grateful if someone, with better marine knowledge than I, goes through these records in greater detail than my preliminary investigations.
The most direct evidence of ocean farming is given in this paper. Despite their high energy requirements, sperm whale distribution correlates highest with photosynthetic productivity at the thousand kilometre scale. This implies (and it can be shown) that some of their highest concentrations are in waters of poor productivity. Waters that are only worth the effort because of their potential to fertilise other down stream areas.
To get shamelessly anecdotal over this matter, the most famous sperm whale ever, Mocha Dick, had such sever respiratory abnormalities, that his breath was said to sound like a steam engine venting. This might have made deep diving very difficult for him, yet he seems to have been one of the biggest males ever observed. Could it be that having a medical excuse for not performing his duties provided him an advantage? For such an infirmed sounding animal, he certainly displayed a surprising excess of energy, and seemed to have endless free time in which to liaise with humans.
Above is a surveyed distribution of sperm whales. You should compare it with the map below for the global distribution of plankton. A direct match can be either cause or effect, but some patterns are easier to interpret as the product of sperm whale fertilisation. See how the highest density of North Atlantic plankton only begins in a dense population of sperm whales, but that the gulf stream carries those mineral deposits north. The result is that you can see the region of highest mid-ocean fertility smear over to areas with very low sperm whale populations. You should also note that there are other apparent mismatches.
The greatest discrepancy between the two is round the Antarctic Seas. This is a survey problem not a real one. Giant male sperm whales are about three times more massive than females and spend most of their time feeding in these waters. Since the Southern Ocean has a much smaller area than tropical and subtropical oceans, the concentration of sperm whale activity should be at least an order of magnitude higher there than elsewhere. Even if they havent been as comprehensively studied in these southernmost waters, we know they are there.
To finish, I will derive a ballpark figure for the magnitude of this farming-like effect prior to the advent of commercial whaling. Estimates of their prewhaling population run from 1-2 million, let’s say it was 1 million. Each consumes, on average, a ton of food a day, and we have one peer-reviewed value for their fertilisation of Antarctic waters of 6kg of plankton and algae produced for every 1kg of food they consume. Let us assume we can extrapolate that value worldwide. This gives us an annual ‘crop’ of 2,000 million tons compared to our modern figure of 700 million for wheat. If we take all our crops combined, humans would have surpassed their former footprint in our last generation, but we should not congratulate ourselves just yet. Our current crop yields are not naturally sustainable, but require increasingly difficult methods to hold. It remains to be seen whether we have the intelligence to achieve that, as sperm whales must have done for thousands of years before us.
It might be tempting to think that fertilising the oceans is easier than the land, but there is evidence that the reverse is true. In the ocean shallows, where there are no sperm whales to oversea it, ocean fertilisation often leads to toxic algal blooms that kill all higher life.
To reduce our anthropocentric bias, imagine a hypothetical extraterrestrial civilisation examining our planet for signs of intelligent life in the year 1800. That turn of our nineteenth century is more than a hundred years after Newton’s Principa, and well into the industrial revolution. They would find a planet with a biosphere completely dominated by a single species of whale. I wonder, would they take a closer look at those sperm whales first, or would they begin their further investigations by looking at a species with barely 20% their ecological impact? If they did find intelligent life in the ocean, would they follow up by next investigating those strange and small creatures on land or would we get lost in the excitement of their initial discovery. I find that thought sobering.
CONTINUE to find if sperm whales once had domesticated animals that were given up to avoid the attentions of whalers