Co-management of Chile’s escaped farmed salmon

provide the ability to observe early signs of overcrowding and take appropriate actions. It is important that interventional measures are implemented before the critical density levels and crowd instability are reached. Two metrics are key in making such determinations: Crowd density in a restricted area gives insight into the current state of the crowd, and the crowd flow provides information about the input rate, and thereby, the rate at which density is increasing. These two metrics together can provide an estimate of the time that it may take for the crowd to reach critical density levels. A range of methodologies developed by computer vision scientists apply artificial intelligence to infer these important parameters from real-time surveillance video footage. Real-time estimation of crowd sentiment, using indicators such as social media activity (5, 6), could further inform real-time interventional decisions. Crowd crushes are preventable, and the required tools and knowledge do exist. They only need to be implemented. Milad Haghani1* and Ruggiero Lovreglio2 1Research Centre for Integrated Transport Innovation, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia. 2School of Built Environment, Massey University, Auckland, New Zealand. *Corresponding author. Email: milad.haghani@unsw.edu.au