Interannual Nearshore Habitat Use of Young of the Year White Sharks Off Southern California

Young-of-the-year (YOY) and juvenile-stage white sharks may use southern California nearshore beach habitats more extensively than previously known, within meters of some of the most heavily used beaches in the world. Such knowledge forms a critical component of species management and conservation plans, in addition to public safety and risk mitigation planning. We used data derived from a combination of satellite tag locations (13 animals over 3 years) and passive acoustic monitoring (34 animals over 8 years) to examine the occurrence, relative abundance, and residency patterns of YOY white sharks in southern California waters. Our results suggest that southern California contains spatiotemporally dynamic centers of primary nursery habitat. Tagged YOY white sharks formed loose aggregations at “hotspot” locations that were interannually variable, where individuals exhibited temporal fidelity, higher levels of residency, and spatially restricted movements, with multiple YOY individuals simultaneously displaying this behavior. While models of biotic and abiotic variables suggested relative abundance of tagged sharks may be predicted by sea surface temperature, salinity and productivity (chlorophyll-A), these predictors were not consistent across all years of the study. Thus, novel approaches that incorporate technologies to derive high resolution environmental data, paired with more comprehensive telemetry datasets are therefore required to better understand the extrinsic factors that drive habitat selection and residency patterns in juvenile white sharks.

Tracking a Marine Ecotourism Star: Movements of the Short Ocean SunfishMola ramsayiin Nusa Penida, Bali, Indonesia

Ocean sunfishes, Molidae, comprise the world’s heaviest bony fishes. They include the short mola,Mola ramsayi(Giglioli 1883), an important tourist draw at Nusa Penida and Nusa Lembongan, Bali, where SCUBA divers can observe ectoparasite-laden individuals being cleaned by smaller reef fishes. Despite widespread appeal, little is known about these fishes relative to regional oceanography. We present the first behavioral information for this species anywhere in the world. Satellite tag data indicate a wide thermal range (10–27.5°C) with depth occupation mostly (95%) in the upper 250 m and habitat preference near the bottom of the warm surface layer. One tag popped off as scheduled after 6 months off Nusa Penida, <10 km from its original deployment. The 3 other tags popped off prematurely: 747 km southeast 89 days after deployment; 142 km south after 7 days of deployment; and 162 km south after 24 days of deployment. Amid mounting tourist pressures and bycatch ofM. ramsayiin eastern regions of Indonesia, such as Alor, behavioral information of this species is essential for effective management and conservation of this valuable marine ecotourism asset.