Approaches to monitoring and assessing toothfish in new and exploratory fisheries, with particular reference to Subarea 88.1

This report presents results from a desktop study to consider approaches to monitoring and assessing toothfish in New and Exploratory fisheries. We review standardised CPUE analysis, quantitative research longline surveys, experimental manipulation of fishing effort, tagging programmes, bottom trawl surveys of juvenile grounds, and acoustic surveys. Because of potential biases we believe that it would be imprudent to rely solely on any one of these methods at the present time. We recommend that tag recapture experiments, or trawl surveys, be used in conjunction with experimental manipulation of effort to monitor toothfish – and perhaps as importantly – the wider ecosystem effects of the toothfish fisheries. We further recommend that simulation studies be carried out to determine the best way to use the effort manipulation approach in all New and Exploratory fisheries, and in particular the current active fisheries (e.g., Subareas 88.1 and 88.2, and Division 58.4.2). Such studies should examine the spatial and temporal scales required for this approach and possible methods (and sample sizes) required to implement the pulsed fishing experiments.