Abstract Investigations into interactions between suspended bivalve farms and the marine environment generally focus on effects to the seafloor beneath farms. This is appropriate in situations where the level of development will be determined by the ability of the growing environment to absorb waste products, such as in the case for finfish culture operations. By contrast, sea-based suspended bivalve culture development is more often controlled by the ability of the water-column environment to supply particulate food material. Therefore, there is a need to develop methodologies and frameworks for assessing the ‘scope for growth’ of bivalve culture, and the level of environmental interactions associated with particular development levels. The work presented here details a set of functional performance indicators that can be used to assess the level of interactions between the culture and the water-column growing environment, and also the farmed biomass with respect to carrying capacity milestones.