Endangered whale sharks in southeastern Brazil: Records and management issues

Abstract

The whale shark, Rhincodon typus, is an endangered fish species for which data in the South Atlantic Ocean are still scarce. This study presents and compares all the known records for this species in southeastern Brazil and recommends strategies to minimize the anthropic influence on its well-being locally and to enhance the database of records. Thirty-eight records were obtained from 1983 to 2020, including sightings (65.8%, n = 25), strandings (21.1%, n = 8), incidental captures in fisheries (10.5%, n = 4), and an incidental capture event followed by sighting (2.6%, n = 1). The results highlight the Rio de Janeiro state coast as an important site for R. typus in southeastern Brazil, where its presence is related to an upwelling zone (22°S-23°S; 41°W-42°W) and warmer sea surface temperature. The highest number of occurrences of R. typus on the Rio de Janeiro state coast was from February to May; this may be related to the seasonal availability of prey or even to the regulation of prey availability by sea surface temperature. Another feature that may attract R. typus individuals to this region is the offshore platforms positioned along the Campos Basin. The records do not indicate that the coastal waters from Rio de Janeiro state have potential for seasonal tourism activities based on R. typus presence. Although the feeding behavior of R. typus was not explicit from our records, we might infer that the coastal waters between 22°S and 23°S and 41°W-42°W are a feeding site in the southwestern Atlantic Ocean.