Unveiling population processes in a tropical sequential fishery: Seasonal catchability in the shrimp fishery of Campeche Sound

Age-specific catchability ( q a ) estimation is essential for fishery assessment in sequential, multi-fleet fisheries that are spatially segregated and exploit different components of the same population. This study analyzes q a patterns in the tropical pink shrimp fishery, incorporating sequential catch-effort data from an inshore illegal artisanal fleet (2018-2019 season) and an offshore industrial fleet (2018 - 2022 seasons) in Campeche, Mexico, representing a novel integration for the sequential fishery. Monthly seasonal q a vectors for each fleet were calculated using a transition matrix-based approach and fitted to a nonlinear function. The rates of change in vulnerability within the available age-structure population were assessed using monthly slopes per fleet. Results show variability in vulnerability consistent with pink shrimp biological processes related to ontogenetic habitat use. Small juveniles (<1.5 months old) are highly vulnerable in inshore habitats most of the year due to continuous lagoon recruitment, with an age shift toward migratory preadults during summer (<3 months old). In offshore grounds (3 to 10 months old), vulnerability shows high seasonal and age-related variability in marine recruitment and reproductive aggregations, suggesting that biological, environmental, and fishing factors may drive q -at-age variability across fishing seasons. The seasonal q rate-of-change patterns per fishing ground enhance understanding of vulnerable population processes and provide an operational framework for the possibility of adaptive, ecosystem-informed management in tropical sequential fisheries.