Indicators of fishing pressure and seafloor integrity

Abstract Piet, G. J., and Hintzen, N. T. 2012. Indicators of fishing pressure and seafloor integrity. – ICES Journal of Marine Science, 69: 1850–1858. This study calculates a suite of indicators reflecting the spatial extent of fishing and its impact on the seafloor and discusses the usefulness of these indicators to inform future management and the issues to consider. It explores several methods to calculate the indicators and shows that they can be informative to report on both fishing pressure and the status of the seafloor. However, although observed overall trends were robust against the specific method of calculation, the absolute values vary greatly with the calculation method. As both aspects are important from a policy perspective, agreement on the methodology to calculate the indicators is required. This study based on the Dutch Exclusive Economic Zone (EEZ) shows that it is possible to calculate indicators required to inform decision-makers on the pressure of fishing as well as the status of the seafloor pending a decision on the following issues: (i) choice of an appropriate grid cell resolution, (ii) use of interpolated VMS tracks instead of VMS position registrations, (iii) choice of an “intensity threshold” dependent on the benthic community recovery capacity, and (iv) the level of confidence required when assessing if an area is not impacted.