Aquaculture for all

Can bivalve aquaculture prevent the “widespread institutional failure” of our attempts to tackle climate change?

Climate change Production systems Mussels +4 more

Bivalve mollusc farming and microalgal farming enterprises provide viable, profitable and sustainable alternatives to all the industrial carbon dioxide capture and storage technologies being promoted today.

by Freelance writer
Dr David Moore thumbnail
Matthias Heilweck thumbnail
Research engineer
Peter Petros thumbnail
Rope-grown mussels

© Offshore Shellfish

“Deep-rooted, widespread institutional failure” is one of the headlines of the Dasgupta Review by Prof Sir Partha Dasgupta, of the University of Cambridge, in the Economics of Biodiversity.

Published on 2 February, this detailed review was commissioned by the UK Treasury in 2019 – the first time a nation’s finance ministry has authorised a full assessment of the economic importance of Nature. The central conclusion is that sustainable economic growth requires a different measure than gross domestic product (GDP).

Or, in the words of Prof Dasgupta: “Truly sustainable economic growth and development means recognising that our long-term prosperity relies on rebalancing our demand of nature’s goods and services with its capacity to supply them."

A flavour of the findings of this authoritative 600-page review is given by its main headlines, which are:

  • Our economies, livelihoods and well-being all depend on our most precious asset: Nature.
  • We have collectively failed to engage with Nature sustainably, to the extent that our demands far exceed its capacity to supply us with the goods and services we all rely on.
  • Our unsustainable engagement with Nature is endangering the prosperity of current and future generations.
  • At the heart of the problem lies deep-rooted, widespread institutional failure.
  • The solution starts with understanding and accepting a simple truth: our economies are embedded within Nature, not external to it.
  • We need to change how we think, act and measure success.
  • Ensure that our demands on Nature do not exceed its supply, and that we increase Nature’s supply relative to its current level.
  • Change our measures of economic success to guide us on a more sustainable path.
  • Transform our institutions and systems – in particular our finance and education systems – to enable these changes and sustain them for future generations.

Most sectors of the seafood industry will recognise this “institutional failure” whether it extends from the most recent post-Brexit red tape causing blockages of some UK exports to the EU, to persistent failure, around the world, to control overfishing in international waters. So, what does “We need to change how we think, act and measure success” mean for the industry? Well, we have a few suggestions which we explore in recent publications.

We have noted before that large scale shellfish cultivation could contribute to remediation of the atmosphere, for the simple reason that about half the weight of a shellfish harvest is the shell and shell is made by removing carbon dioxide from the atmosphere and turning it into limestone (calcium carbonate) which can last for millions of years. But this is where we need to change how we think and act, because we need to change the paradigm to cultivate shellfish for their shells, developing a new generation shellfish farming aimed at whole-planet ecosystem repair and restoration.

Commercially grown bivalves are among the most sustainable forms of human food, so shellfish cultivation is the only industry on the planet that can massively expand without damaging the atmosphere. Furthermore, we estimate that a mussel farm sequesters three times as much carbon as terrestrial ecosystems retain.

Changing the paradigm allows the food value of the animal protein to be taken as one of the several ecosystem services that bivalve molluscs (and calcifying microalgae, that is coccolithophores) provide. But a bivalve mollusc farming enterprise operating to cultivate shell in which atmospheric CO2 is captured and stored, also produces nutritious meat and while these molluscan ecosystem engineers are growing, they perform several other ecosystem services (water filtration, biodeposition, denitrification, reef building, enhancing biodiversity, shoreline stabilisation and wave management). About 70 percent of the Earth’s surface is covered by water. We might as well use it sustainably to rescue our atmosphere, our planet, and ourselves.

A positive characteristic of calcifier farming is that it presents no conflict between using land to grow food crops and using land to grow trees, or as pasture for farm animals. There is no need for irrigation, feed, or fertiliser. Farming shellfish can be combined with restoration and conservation of overfished fisheries and usually involves so little intervention (beyond provision of habitats and, where necessary, protection of larvae and juveniles from predation (in nurseries) that there is no inevitable conflict with other activities.

As well as comparing shellfish farming with conventional terrestrial farming, we have also compared shellfish farming with the current artificial/industrial carbon dioxide capture and storage technologies being promoted today. These are technologies that extract CO2 from exhaust and flue gases and depositing the captured CO2 in geological formations. They are widely promoted as a means by which the fossil-fuel burning industries can comply with the Kyoto Protocol, completed in December 1997, that required industrialised countries to reduce their total greenhouse gas emissions to 5.2 percent below 1990 levels.

Unfortunately, carbon markets (or global emissions trading schemes) have emerged from this activity that many would agree have failed in their primary objective of ensuring significant reductions in greenhouse gas emissions because they are effectively ways to buy, sell and profit from the right to pollute. The critical question that needs to be asked is whether the future of humanity on this planet would be better served by markets based on global health rather than global pollution?

Our study brings home the fact that, even if you create an effective industrial carbon dioxide capture and storage facility, that is all you get: captured CO2, nothing else. We calculate that the paradigm shift we have referred to (cultivate shellfish for their shells) would make bivalve mollusc farming and microalgal farming enterprises, viable, profitable and sustainable alternatives to all the industrial carbon dioxide capture and storage technologies being promoted today.

We find that it is likely that twice as much oil and gas would have to be extracted simply to store the CO2 emitted by the current use of these fossil fuels. Furthermore, between the additional energy required for industrial CCS, the CO2 emissions during the process and its leakage during storage (the risk of which certainly increases with the years), we consider that widespread use of CSS would be like being blindfolded on the edge of a precipice and taking a big step forward!

We also believe that there is scope for greater use of the High Seas to replace forage fish with mussels in the diets of farmed fish and produce the increasing amounts of food that will be required by the growing human population, whilst at the same time pulling down carbon from the atmosphere with bivalve cultivation. The vision is to preserve the oceans as a healthy and sustainable food source for mankind by emphasising conservation and ecosystem balance beyond coastal waters. The plans are for huge (centralised) bivalve mollusc farming facilities on the High Seas, using factory ships and offshore factory rigs (re-purposed disused oil rigs?) located on seamounts outside Exclusive Economic Zones and employing Perpetual Salt Fountains on the flanks of the seamount to bring nutrients to the farms. If properly designed (and the design and building capabilities exist throughout the offshore industries around the world), this will immediately provide (i) feed for animals and food for humans, (ii) sustainable marine ecosystems, and (iii) permanent atmospheric carbon sequestration in the form of reefs of bivalve shells.

Now there are a few entirely feasible transformative changes that are worth consideration; as Prof Dasgupta says, “we and our descendants deserve nothing less”.

Further information

Further information can be accessed by downloading the following (free) PDFs:

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