Environmental factors that influence the abundance of potentially dangerous sharks in nearshore areas
A newly released paper by SIMS’ Dr Kate May, and co-authored by Dr Vic Peddemors from the NSW Department of Fisheries, Professor Rob Harcourt from Macquarie University and UNSW’s Associate Professor Moninya Roughan has used long-term datasets from shark mitigation
programs to help determine the environmental conditions that influence
abundance of potentially dangerous sharks.
25 years of shark
catches were used to model the abundance of all potentially dangerous shark species and
individual species to determine: (1) the spatial variability in catches
and (2) the oceanographic and physical variables that could influence
Overall, sea surface temperatures (SST), El Niño events, moon illumination, and beach
length influenced the abundance of shark groups tested. White shark abundance
was highest during water temperatures of ~17-18°C and declined when SST
increased above 19°C. Whaler abundance increased with higher SSTs.
Shark abundance was higher during El Niño events than during La Niña, although
the number of whalers caught was highest during neutral phases. All groups
showed a decrease in the number of catches with increasing moon illumination
and higher abundance on longer beaches.
Dr. Kate May : These results may aid public safety
methods aimed at reducing human-shark encounters by highlighting when higher
numbers of sharks may occur.