There has been much recent discussion over the need for an ‘ecosystem approach’ to be taken to the management of human activities both on land and at sea. There are a number of definitions of ‘ecosystem approach’ but a common feature is the need to set objectives for management. The ecosystem approach to management encompasses effects on the ecosystem as well as social and economic effects. Top predators are a key part of the marine ecosystem and thus objectives ought to be set for them. Objectives that might be set are broadly of two types: ‘what do we want to achieve’ (targets); and ‘what do we not want to happen’ (limits). Objectives may describe several aspects of the system for which they are being set – commonly objectives are set for the state of an animal population or for the impact on that population. If objectives are to be useful they need to be achievable, inter-compatible and responsive to management actions. A major initiative in European waters at present is the establishment of Ecological Quality Objectives (EcoQOs) in the North Sea, but other implicit objectives have also been set for marine top predators. In relation to top predators, societal wishes are usually related to the state of populations which integrates across a set of measures including population size, growth, range, health and feeding relationships. It is often not possible to measure these aspects of state easily or sufficiently widely to understand what is happening to a population as a whole.