It is unknown whether the current apparent failure of the stocks to recover in the NP Tiger fishery is related to limited management options, serial depletion of stocks or to the use of the now somewhat discredited MSY and EMSY management targets (see, for example, Larkin, 1977 and summaries in Pitcher & Hart, 1982).

In two recently completed FRDC projects (FRDC 95/014 and 98/109), a preliminary attempt at stock-based assessments was undertaken. These show that some stocks are much more depleted than the single-stock model would suggest. There is a need to clarify which areas are most affected and why these are performing so poorly. There is also a need to develop a multi-stock operating model to open a new direction for modelling in the NPF. This technically complex model would have the potential to benefit the management of benthic crustacean species worldwide. (It should be noted that no operating model, particularly not a spatially explicit one, has been developed for any prawn fisheries in Australia.)

In species, such as prawns, whose dynamics are dominated by yearly recruitment variation, the MSY may well give a false expectation of stability. Management targets that relate to present conditions rather than to equilibrium conditions (e.g. a target fishing mortality rate) may better serve intrinsically variable fisheries, such as prawns. However, reference points developed worldwide have concentrated on output controlled management systems. Given AFMA’s requirement to satisfy its ESD objective, there is therefore a need to consider uncertainty explicitly and to identify performance indicators and harvest strategies that are as robust as possible to incorrect assumptions and estimation errors deriving from limited data. Most importantly, these should be developed in the context of spatially explicit stock assessment models and an input controlled management system.