The development of an operational model and simulation procedure for testing uncertainties in the Atlantic big eye (#Thunnus obesus$) stock assessment

Abstract : Atlantic bigeye is a highly migratory species widely distributed through the whole Atlantic. Recent assessments conducted by the ICCAT SCRS are highly uncertain due to the large uncertainties in biological parameters, such as M, as well as in fishery statistics (e.g., IUU fleets, juvenile catch) or abundance indexes. Similar uncertainties can be found in the Indian or Pacific stocks. The development of an operational model has been recommended by different regional fishery organizations as a good approach to investigate the sensitivity of the assessment results to the uncertainties in the different inputs. This document presents an operational model for the Atlantic bigeye as part of a simulation framework that will allow the performance of management strategies based on current and improved biological knowledge and management procedures to be evaluated.