Eiffel Over

Tag: NaturalResources

  • No more fish in the sea

    Somehow the topics of my posts have returned to the subject of the sea. It is apparently a rich subject to trawl.  Sorry, I couldn’t resist the pun, but it is exactly to trawling that I am heading. 

    Yesterday I used Donella Meadows’s fish stocks example to show how humans can harvest a living resource while enabling it to thrive. A key to enabling this system to work is the balancing feedback loop between supply and the people doing the harvest. When the catch gets too low, the boats go home, and the fish can restore their population.

    But what happens when that balancing feedback loop is broken? 

    Let us imagine an entrepreneurial fisher who, noticing that their catch was diminishing, decides to invest in a much bigger net. Now their catch goes up and it is worthwhile for them to stay at sea for longer. Other boat captains do the same, and the fleet stays out much longer. 

    Now, rather than the fish population having time to replenish itself, it is further depleted. When the fish are further apart, their rate of reproduction diminishes. 

    Here, trawling is breaking the balancing feedback loop between supply and harvesters. So, instead of stopping, fishing continues and the population becomes so low that it is not able to grow back. It has become what is known as a ‘desertified state’, a vulnerable situation in which a living system can no longer thrive. 

    Clearly, this is a simplified version of a much more complex system. But hopefully it serves to illustrate that in thinking about how we scale up options, we need to think about how we might inadvertently be breaking the feedback loops that enable our activities to operate within the living system’s limits.

  • Plenty more fish in the sea

    Yesterday’s post on the fish écluses on the Île de Ré speaks to the idea of creating straightforward connections between the resources that humans need to live and thrive. 

    As engineers (and other humans) we need to find ways to harvest the materials and energy we need in balance with what the living and mineral world can sustain. So to help us understand how this can work I’m sharing Donella Meadows’s example of fish stocks to help see how humans can live as part of a sustainable system of supply.

    Meadows’s model concerns the local fish population in an area of sea. Left to its own devices, the fish population is stable because there is only so much food to go around. Too many fish, less food per fish, some fish die. Too few fish, more food per fish, they reproduce more. This feedback loop stays in equilibrium around a mean.

    Now, the local fishing fleet gets involved. By harvesting a small number of fish, the population goes down, increasing the reproduction rate of the remaining fish, and the population returns to what it was. Fish too much, however, and the fish are further apart. Fish that are further apart take longer to reproduce! And so for a while, there are few fish, the nets are empty and the boats go back to port. During this time the fish population recovers, and eventually the boats can go back to sea.

    This simplified model beautifully illustrates how humans can harvest what they need while still living within the ecosystem’s limits.  The key characteristics here are a living system that regenerates itself – the fish; and a feedback loop between supply and those doing the harvest. Simply, when the catch is too low, the boats go home. 

    This feedback loop between supply and harvesting is what interests us in regenerative design. It is what allows us to harvest abundance, and even create abundance, all while living within the ecosystem’s limits.