Assessing the stock status of <italic>Euthynnus alletteratus</italic> (Rafinesque 1810) exploited by tuna purse seiners in the Northeast Atlantic Ocean: implications of using the length-based Integrated Mixed Effect model.

<italic>Euthynnus alletteratus</italic>, a crucial commercial resource for West African states in the Northeast Atlantic Ocean (ATNE), is of high research priority in the Atlantic Ocean, but its stock assessment is limited. This study aimed to explore the implications of integrating length, catch and abundance indices on the status of ATNE stock using the LIME model. We innovatively developed time series of abundance indices using tuna purse seine catches and efforts obtained from separate ICCAT datasets, alongside length-frequencies. The scenarios (S) S1 (length-only), S2 (length + catch + abundance), S3 (length + catch), and S4 (length + abundance) were considered. We observed that S1–S3 did not converge in LIME, except for S4. The stock's spawning potential ratio and mean length were below the target (SPR< 40%) and 95% maturity length (M95), respectively. By implication, the lack of convergence in S1–S3 portrayed data conflicts, which were mitigated by the abundance index in S4. A mean length above M95 is recommended when evaluating the stock using the length-only option in LIME. The stock was unsustainable, requiring management measures. Integrating the abundance index with length improved the performance of LIME for the stock, which estimate could be replicated for other species' assessments. [ABSTRACT FROM AUTHOR]