Tidd A. auteur aut IRD Dagorn Laurent auteur aut IRD Capello Manuela auteur aut IRD Travassos M. auteur aut IRD Guillotreau Patrice auteur aut IRD text journalArticle eng text/pdf reformatted digital access Managing fishing effort remains a central challenge in achieving sustainability in many fisheries, particularly where high-value species attract intense competition. In the Indian Ocean tropical tuna fishery, understanding how fishers respond to changing bio-economic conditions is essential for developing effective management. This study evaluates the influence of effort-based management measures on the size and investment behaviour of the purse-seine fleet targeting skipjack (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares). Using Random Utility Models (RUMs), we identify the key economic drivers of strategic decision-making, validate them through model evaluation, and integrate them with age-structured operating models (OMs). The RUM achieves 93% predictive accuracy, offering a robust basis for exploring policy options that balance conservation and economic objectives. Scenario testing under different cost and price conditions illustrates how economic pressures shape entry and exit decisions within the fleet. specialized decision-making entry-exit fishing capacity indian ocean sustainability tropical tunas OCEAN INDIEN ZONE TROPICALE 040 020 021 [Early access] [11 p.] 2026 0969-997X https://www.documentation.ird.fr/hor/fdi:010096906 10.1111/fme.70071 0969-997X [F B010096906] https://www.documentation.ird.fr/hor/fdi:010096906 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2026-05/010096906.pdf IRD - Base Horizon / Pleins textes 2026-05-20 2026-06-12 fdi:010096906 fre