Whale Poop and the Plankton Paradox

Don't mess with stuff you don't understand.

They used to have massive pigeon shoots in East Anglia fifty or sixty years ago. Can’t quite remember when and can’t find the references now, but the details are still clear in my mind. They still have pigeon shoots now of course – you can book them online all over East Anglia if you think it sounds like fun. To get the General Licence (an exemption to the Wildlife and Countryside Act to allow farmers and landowners to shoot protected wild birds) you’ll have to pretend to have gone all the way to Norfolk to help the farmers out, but that needn’t spoil your fun too much. An outfit like https://www.gunsonpegs.com will probably deal with the paperwork for you, and DEFRA make it as easy for you as they can. In the good old days before the Wildlife and Countryside Act of 1981 you could pretty much shoot anything. But the pigeon shoots of East Anglia still weren’t anything like the campaign against the Passenger Pigeon in the States, which eradicated the most numerous bird species on the planet in less than 50 years, with special trains laid on to take the hunters to the pigeons and the corpses back to town. Of the pigeons, unfortunately, not the hunters, though I expect a few of them shot each other in the general excitement. It’s exciting, you see, killing things. They tell me.

Those Norfolk farmers did their best, of course. But the odd thing was that no matter how many they shot over the years they didn’t seem to be reducing pigeon numbers. Eventually ornithologists figured out that the farmers were mostly shooting the slower and lower birds, the weak, the diseased and the elderly. The ones they missed were the healthiest, the best breeding stock. And the pinch point for the population was in March, when food was running out. So the sprouts and cabbages and suchlike still available on farmland in March were eaten by the fittest pigeons and there was more to go round, and they went on to start the breeding season so fat and fit that they could manage three clutches of eggs instead of the more usual one or two. Which kept the numbers up.

In a way it doesn’t matter if I have remembered the details correctly, because what is important here is that this feeds into familiar narratives about things like sustainable fishing. The fisheries biologists supervising ‘resources’ such as the cod fishery on the Grand Banks off Newfoundland based their suggested  catch quotas on similar narratives. You catch the right amount of a fish species,  and the survivors will do better because they will have more food, and you can, with international agreement, set theoretically sustainable catch quotas, which will tend to be as high as competing nations can get away with. The problem with this narrative is that it treats a complex ecosystem as if there are only three variables –  cod food supply, cod population, and cod catches; other creatures and variables may not be included in the calculations. Add human greed, and the Grand Banks cod fishery disappears, possibly for ever.

The nations that still wish to hunt whales use that kind of narrative too. The North Atlantic Marine Mammals Commission (NAMMCO) pushes the following kind of line:

 “Our unique form of whaling in the Faroes is largely non-commercial – that is the way it has developed over centuries as a part of Faroese food culture. But we also fully respect the rights of others to trade commercially in their [my italics] marine mammal resources, also on international markets,” he said. “We have seen how a global organization, the International Whaling Commission (IWC), is still unable to find common ground on the management of whales as resources. After nearly four decades, the global ban on commercial whaling is still in place. This is because many of the IWC members do not consider whales as resources and have blocked decisions on sustainable [my italics] whaling quotas. By doing this, they are actually leaving whales out of the [United Nations’] sustainable development goals, and they are ignoring the rights of peoples to benefit from their own [my italics again!] natural resources. This is unacceptable. Even if countries do not themselves consume marine mammals, they should respect the rights of others to do so.” 

A load of crap, you might say. I’ve been wondering what word to use, because shit is a bit rude and excreta a bit too scientific-sounding. You see, I have been thinking about whale poop rather a lot recently, hiding in my kitchen from the virus and the rain. I started off wondering why, it seems, that after the IWC ban on whaling in the Antarctic some species have been slow to recover. This is an important preoccupation, because those of us wishing to see the recovery of the biosphere tend to worry about passing ‘tipping points’ beyond which recovery may not be possible, as on the Grand Banks cod fishery. And we know that animal breeding behaviour is complex and fragile. They failed to get the last handful of Passenger Pigeons to breed, for example, almost certainly because their breeding ecology depended on their being in big flocks*. Isolated pairs just couldn’t get it on. Small colonies of Herring Gulls fail to breed until they reach a critical level of 10 or 12 pairs.

Whales seemed likely to be able to find each other by calling over vast underwater distances, but the more complex and intelligent the animal the more likely it seemed to me that they might have complex social behaviours around mating and rearing young. One thing leads to another when the laptop is open on wet dreary days, and I went on to think about whale food and then about what I have decided to call whale poop.

In the twentieth century we slaughtered maybe 3 million whales, mainly in the southern oceans around Antarctica. These are big beasts, the size of jumbo jets. A Blue Whale may consume 16 tonnes of krill daily, a Right Whale about 5 tonnes of small zooplankton per day. That’s an awful lot of whale poop. I started thinking about how the fertility of unimaginable quantities of whale poop from 3 million slaughtered whales might  have affected the nutrients in the sea that ‘manure’ the growth of huge ‘blooms’ of plankton on which many of the big whales feed. According to the simple fish-stocks theories you might imagine that fewer whales would result in more plankton to go round. The truth is that since the whales were slaughtered there is less plankton than when they were abundant – what had been called the plankton paradox. I started, in a farmery sort of way, musing that maybe whales had been manuring the oceans, creating a system that recycled endlessly the nutrients that supported the phytoplankton that supported the zooplankton that fed the krill that fed the whales that produced the manure that nurtured the plankton. Motion made perpetual by the addition of solar energy powering the photosynthesis of the phyto-plankton at the bottom of the food chain.

It turns out that whales are more important than anyone could previously have imagined at recycling nutrients in the ocean, nutrients that would otherwise settle to the ocean floor without whales to recycle and recirculate them. I’m beginning to suspect that whales may poop when they come up for air, and  I happen to know that whale poop floats for a while, because I take an interest in that kind of thing. It is important that nutrients are brought near the surface because the phytoplankton at the base of the oceanic food chains needs sunlight in order to photosynthesise. It also turns out that whale poop is particularly good at keeping the iron levels up in the nutrients they circulate, and that the level of iron in these ocean nutrients is the main limiting factor for phytoplankton blooms.

The implication of all this, for climate change and for biosphere restoration, turns out to be colossal. Restoring whale populations to pre-whaling levels could restore lost marine productivity by about 11% and increase carbon draw-down into the oceans by 215 million tonnes,  ‘absorbed and stored in ocean ecosystems and organisms in the process of rebuilding’.  Scientists conclude that ‘the contribution of whales to global productivity and carbon removal (was) probably on a par with the forest ecosystems of entire continents’.

‘That system is still there, and helping whales recover could restore lost ecosystem functioning and provide a natural climate solution.’

I’ve strayed here somewhat from our familiar landscapes, but they say local is global and global is local. And it illustrates once again how dangerous it is to over-exploit or to damage the biosphere, whether by whaling in the Antarctic or by the use of pesticides on the farm next door, when we are still trying to work out how it all functions.