By Brendan Moyle 26/07/2017

The one thing that has really changed in the last century is the size and scale of human effects on the environment.  

This isn’t to say we didn’t have impacts before.

As humans spread over this globe, many vertebrate species became extinct. Whether it’s the giant mammoths or giant moas, humans alter the world around them.  What is different is the scale of these changes now. We are able to alter the climate and damage large ecosystems in ways our early ancestors never could.  It’s a combination of two factors.  The size of the human population and what we consume.  It’s at a scale where what we do, makes a big impact.

One example is agriculture. A few thousand years ago, when a small number of human communities began gathering some sheep, or goats, or cows to keep, didn’t really have a big global impact.  Now, there’s a lot more humans and a lot more farmed ruminant animals.  This is well illustrated in the xkcd comic below.  I did check the numbers and they seem roughly in the right ball park.  There’s been a massive shift in biomass on our planet.

What this has meant, is a large scale replacement of many forest systems with grasslands better suited for ruminant grazing.  We did it NZ. The loss of native forests with human settlement in NZ is one of our legacies. It happened infamously in the Brazilian Amazon.

Ruminants in the long-run, were probably a bad bet for us.  They need a lot of water, they need large areas to feed on, and they produce a lot of wastes.  That isn’t just fecal material. That also includes methane and other green-house gases.

Why can’t we all be vegetarian?

There are a lot of good reasons to shift toward a more plant-based diet. It’s a healthier diet option. It’s associated with less green-house-gas emissions. It needs less area than animal-based agriculture.  This is a result of moving down the food chain.  It’s from a biomass perspective, better to eat plants than to feed them to animals, to eat further up the food chain.  With nearly 8 billion humans now living on this planet, that starts to be compelling.

Nonetheless, there are still issues for our Green consumer.  The first is that you don’t get any Vitamin B12 unless you take supplements, eat food fortified with it, or consume dairy products and/or eggs.  If you consume dairy products, that’ll produce less GHG emissions than meat (see below).  Nonetheless dairy farming is still associated with the deaths of many animals.  Bobby calves tend not to live long, rich and full lives.  So if one of your concerns is reducing animal deaths associated with agriculture, it’s not plain sailing by simply adding cheese.

FAO graph on GHG emissions associated with protein production

Eggs are another option. You can go organic and free-range. That’s laudable. It reduces suffering.  You’ll get your Vitamin B12. But the problem is all the male hatchlings.  They don’t live full rich lives. Once they’re out of the egg and looking around at the world, their maleness is a death sentence.  So while the eggs themselves don’t require the animal to die, there’s a lot of collateral damage.

So what about the fortified food option for B12?  Well, it’s commonly added to cereals in other markets (like the US). The problem is vegetarians as a whole, aren’t reaching for brightly coloured packages of highly-processed breakfast cereals.  They’re notoriously bad at it.  They eat simpler food (yeah…I eat plain porridge for breakfast). Not that we tend to add B12 to cereals in NZ.  It can be found in small levels in Marmite, and is added to Milo.  And there’s also pills.

Vitamin B12 has become an increasing problem for me because I consume a lot less dairy products and eggs now. Milo was dropped a few years back because I didn’t like the taste of the new formula.  And I don’t eat Marmite.

To the sea!

Seafood (kai moana) seems to resolve a few issues. You’ve got your B12 sorted.  Fish by and large are still wild food. We don’t produce them with fertiliser, apply pesticides or antibiotics (albeit some farmed fish require some of these). They’re not ruminants so they don’t produce a lot of GHG emissions.  NZ tends to have well-managed fish stocks.  So the spectre of over-fishing is at least, less of an issue for consumers here.

Still, a couple of problems remain. First, it is still about killing other animals for protein. The second is the bycatch problem. When the nets go down, target species aren’t the only fish that are caught.  Other marine species are caught. This increases the collateral damage again. We’re still not free of the inflated casualties associated with the dairy and egg industry.  Perhaps less suffering is involved, but can we do better?

Going Green

NZ green-lipped mussels start to tick a lot of boxes.  They supply oodles of B12 and other good nutrients.  The farming system requires few inputs.  We don’t apply antibiotics or fertilisers, or feed them.  The bivalves sit on lines underwater, filtering algae from the sea to consume and grow.  The bycatch is restricted to well, some barnacles that might grow on some of the shells. So from an ecological perspective, this looks attractive. They’re also a relatively cheap source of protein.

What about the suffering side?  Well, having dissected bivalves way back in my science degree, they have very little nervous tissue. Certainly nothing like a central nervous system.  Brains are metabolically expensive. A creature that doesn’t move and eats algae, doesn’t need a brain.  They don’t have one.  Their ability to register pain and suffering is as close to non-existent as we could get for an animal.

Kale might be the way forward after all.

Production methods for mussels overall, also have a low level of collateral damage.  This may seem a tad paradoxical compared to a strict vegetarian or vegan diet.  Nonetheless, we grow plants by largely intensive monoculture.  Fields are given over to produce one plant crop.  Pesticides are used to control insect pests.  Fertilisers are applied to promote growth.  These monocultural systems are low on biodiversity.  To maintain them, we kill large amounts of insects and other invertebrates.  And insects have much more elaborate nervous systems than bivalves like mussels.  Their capacity to suffer is much higher.  So from both an ecological and a welfare perspective, mussels aren’t the worst thing to eat.  A bowl of lentils probably has a much higher animal-kill count associated with it than farmed mussels.


Ideally, your green consumer is striving for food that has the lowest ecological and welfare costs, while still maintaining a healthy diet.  This requires tradeoffs.  There is no way to be a consumer and not impact on the world.  Even a strict vegan diet with no animal products, will not be able to escape some kind of ‘collateral damage’ somewhere along the food chain.  Nonetheless, what we do eat still makes a difference.  The cumulative effects of diets based on ruminants has altered ecosystems at a global scale. It has pumped so much methane into the atmosphere it contributes to a changing climate.  Shifting toward more plant-based diets helps, but that still has challenges for a healthy diet.  That’s not to say Western meat-based diets are healthy of course.  One solution to this is to add sea food, like mussels, to the diet.