Fishers’ local ecological knowledge recovers information about the recent-past existence of a Caribbean coastal shark and ray nursery area

Elasmobranchs have declined sharply due to overfishing and habitat destruction. Nursery-areas are crucial for the recruitment and sustainability of elasmobranch populations; however, they have been scarcely studied globally and in Mexico. We used fishers’ Local Ecological Knowledge (LEK) to investigate whether Bahía de la Ascensión was an elasmobranch nursery-area 30 + years-ago, and for which species. Shark nursery-areas are defined by three criteria that we evaluated using semi-structured interviews covering 90% of the target population (local fishers aged 40+). Several elasmobranchs met all criteria, supporting that this bay served as a communal elasmobranch nursery-area 30 + years-ago for Carcharhinus leucas , C. limbatus, Ginglymostoma cirratum , Negaprion brevirostris, Hypanus americanus and Styracura schmardae. Additionally, fishers reported changes in early-offspring elasmobranch abundance –including declines and increases– between our study-period and the present. This is the first study showing that LEK can be used to reconstruct the former existence of elasmobranch nursery-areas, highlighting its value to rescue past information in data-poor contexts, in support of conservation. This approach can and should be widely-applied for similar purposes. Our study is part of a trans-disciplinary project examining past-and-present elasmobranch nurseries in the Mexican Caribbean, providing a baseline to evaluate changes while preventing misinterpretation based solely on present-day data.