Fishery monitoring reveals a rare and seasonal occurrence of the threatened tope shark Galeorhinus galeus (Linnaeus, 1758) within a restricted bathymetric range in the state of Santa Catarina, southern B

Abstract

This study aimed to report new records of the tope shark Galeorhinus galeus , a critically endangered species in Brazil, based on onboard monitoring of artisanal bottom gillnet fisheries in southern Brazil, emphasizing its seasonal occurrence and strong association with a narrow depth range. Data were collected between 2021 and 2025 across 168 monitored fishing operations. A total of 14 individuals were recorded in only eight operations, suggesting the contemporary occurrence of the species in the region, where it was consistently recorded at low frequency throughout the monitoring period. All captures were restricted to winter and early spring and occurred within a narrow bathymetric range (48–52 m). Only juveniles were recorded, with similar proportions of males and females. These findings indicate that, despite its rarity, the species continues to use the region in a highly specific and seasonal manner. Overall, the results highlight the importance of continuous fishery monitoring for detecting remnant populations and emphasize the relevance of specific coastal habitats for the conservation of this threatened species.