Cumulative impacts across fisheries in Australia's marine environment
The need for cumulative impact assessment (CIA) is increasingly being recognized. The development process for Australia's Harvest and Bycatch Policies, and their associated guidelines have reinforced the need for assessment of cumulative impacts, and the EPBC Act has also explicitly required consideration of cumulative impacts.
Where multiple activities occur or are planned, an understanding of their combined effects on the environment is necessary to address policy requirements and achieve sustainability. The concept of cumulative impact assessment is not new – indeed cumulative assessment has been recognized for many years, and a range of methods have been proposed around the globe. However, no methodology for undertaking cumulative assessments has been accepted nationally or globally. In addition to considering the impacts across all fishing sectors (commercial, recreational, indigenous, as required by recent changes to the Fisheries Administration Act 1991) and all fisheries, there is also an increasing need to consider other users of marine resources and coastal waters (e.g. renewable energy, shipping etc), especially where space crowding may be an issue.
Target species stock assessments typically consider the species of interest as well as other sources of fishing mortality (e.g. discards), but they do not usually consider their effects on other fisheries sectors or the effects of other sectors on the focal fishery. CIA methods therefore need to consider interactive and indirect effects. To date, interactive effects are often viewed as additive (simple linear addition of one impact to another) with little consideration given to synergistic, antagonistic or non-linear effects. While the ERAEF toolbox used for assessment of bycatch and protected species has some potential options for cumulative impacts (e.g. SAFE method), at this stage they are insufficient for moving to the scales and complexities across multiple fishing sectors and fisheries.
Thus, sustainable fisheries management requires new approaches that consider all sectors and all fisheries and how they impact the environment. Such CIAs will be challenging given that empirical data are often lacking - a dedicated research effort is needed.
