Bass - what does the assessment tell us, what it doesn’t tell us, and what we can learn about management.

No abstracts are to be cited without prior reference to the author.

UK Fisheries for bass do not fit neatly into the ‘standard’ ICES framework for assessments and advice for a number of reasons. The fisheries are mostly inshore, operated from commercial / semi-commercial small boats that are not obliged to provide trip or even area based landings information. The degree to which bass are targeted depends strongly on the relative availability of bass and other target species. A substantial recreational fishery contributes significantly to mortality, yet little or nothing is known about its absolute magnitude or its effects on stocks. Survey information for bass is limited to estuarine recruitment surveys, which are spatially restricted, and there are no fisheries independent measures of adult abundance. In other words, an age-based VPA type approach is unlikely to be helpful in managing this fishery. Or is it? The stock synthesis assessment approach has been able to shed considerable light on some of the most important issues for managers of bass stocks. First and foremost, the stocks are expanding under increasing exploitation levels, suggesting that they are exploited sustainably. Estimated selection patterns for the fleets are robust to uncertainty in F, so that these can be used to explore different exploitation scenarios. Fishing mortality is formally linked to effort. Recruitment estimates from the surveys were independently shown to be efficient predictors of future recruitment despite their caveats. Therefore the measures for effectively managing and monitoring a fishery are available. What the assessments can’t do is provide short-term forecasts for setting TACs, determine PA reference points for assessing stock status or divide the catch fairly between different sectors. These are the things that managers have become to see as the wholly grail of management under the CFP. It is unclear to what degree the bass management success is due to luck, design, biology or plain necessity, but it is clear that bass management would have been much poorer in the absence of detailed biological knowledge and the standard ICES approach of annual TAC setting would not have been practical given the availability of data. This implies that a more individual approach to stock management with considerations of data availability, species biology, fishers’ behaviour and clear management objectives are more important to fisheries management than precise numbers-at-age tables or use of specific assessment models. This presentation discusses the link that the assessment makes between the available bass data and management needs and emphasises the importance of getting this right. This paper does not present any new results or even radically new ideas. It represents a synopsis of the differences between bass assessments and the ICES assessment paradigm