Pyramids of Life: Working with nature for a sustainable future

Our planet's natural resources face unsustainable demands and there is evidence that current management approaches are failing to move resource use towards a sustainable future. This failure is particularly acute in marine ecosystems where about 95% of fisheries are fully- or over-exploited. A step-change is needed to achieve sustainability, but such change can only be affected if it aligns with consumer demand, real world fishing practicalities, and with sustainable national policies such as the Natural Capital Approach described by the UK's 25 Year Environment Plan. The 'Pyramids of Life' approach to a sustainable future captures and helps to communicate complex relationships between different species, human behaviours, and marine ecosystem functions.

Ecological pyramids represent different size-based trophic levels with the relative scarcity of larger organisms being regulated by well-understood scaling principles based on energy flow from smaller prey. Human needs can also be represented in hierarchical pyramids where lower level physiological needs (e.g. need for food) must be satisfied before higher level needs (e.g. need for self-esteem) can influence behaviour (e.g. value systems). If presented together, information from such pyramids would allow stakeholders to understand complex and dynamic systems and their interdependencies, contribute to inform adaptive decision-making and lend itself to efficient and scalable modelling tools based on existing datasets

The problem for the UK's marine resources is that fisheries management agreements typically use metrics which are based, for a given species, on the number of tonnes landed above some given minimum size. This can distort the size structure of naturally productive pyramids, causing local crashes in populations. It can also be wasteful where catches inevitably encompass many species. Consumer preference and market forces also play a role, promoting "plate-sized" catches and well-known species at the possible expense of more ecologically sustainable alternatives.

We have shown that management which better respects ecological pyramids, and where harvest at a particular size class is proportional to the production at that size class (in units of carbon per year), can be both more productive and surprisingly resilient to external challenges. The challenge is to convert this academic observation into practical reality. To do this, we need to understand the behaviour of consumers, and of fishers, and to identify where change can be commercially viable as well as ecologically sustainable. Again the pyramid concept, this time describing values and behaviours, is helpful. Co-development with our partner organisations has identified key target species and fisheries, and existing datasets, where targeted changes in management can align with both the realities of human behaviour and economic value, and ecological sustainability.

The research combines overlapping expertise in socio-economics and human behaviour (University of East Anglia), ecology and detailed spatio-temporal datasets (Cefas),and mathematics and marine ecology (University of York). Our partners Seafish and Waitrose bring detailed expertise in market dynamics, consumer behaviour and fishing effort, as well as matching our commitment to long-term sustainability. Together, this body of work will provide a multidimensional perspective of the value of marine ecosystems so that future management interventions are based squarely on what is sustainable.