School of Biological and Chemical Sciences

Thomas Del Santo O'Neill


PhD student



Project title: Methods and policy pathways to optimise production of multiple interacting fish stocks

Summary: Global environmental issues related to food security, biodiversity, and use of antibiotic, pesticides and fertilizers suggest use of smart mixtures of crops/stocks in agriculture, forestry, farming, and ranching: so-called polycultures. A barrier to this is, however, the complexity of polycultures compared to monocultures. Not only do different species naturally interact, ecological theory predicts that the sensitivity of the composition of polycultures to external pressures (e.g. fertilization, climate, or pests) increases steadily with the number of co-existing species. Hence there is a need for methods to (1) set attainable management objectives for polycultures in light of inherent trade-offs, (2) identify corresponding optimal mixtures, and (3) understand the predictability of outcomes, and of the management intensity required to attain optima in view of inherent uncertainties. When stakeholders with different roles manage and/or use the polyculture one also needs to (4) understand agreeability of objectives. We use the intensely managed mixed fishery of the North Sea as a model system. It is well described by ecological models and the benefits of managing it as a polyculture are acknowledged amongst stakeholders. The aim of this project is to develop the prototype of a management plan, addressing the four problem areas enumerated above, to be used in future fisheries management.