Voyage to the White Shark Café

Barbara Block1, Jan H Witting2, Leif N Thomas3, Nathan Truelove4, Elizabeth Andruszkiewicz5, Taylor Chapple6, Elan Portner7, Bruce H Robison8, Aaron B Carlisle9, Danielle Haulsee10, Salvador Jorgensen11, Paul Kanive12, Amanda Nicole Netburn, PhD13, Scot Anderson11, Tim White3 and Matthew J Oliver14, (1)Stanford University, Hopkins Marine Station, Stanford, CA, United States, (2)Stanford University, Hopkins Marine Station, United States, (3)Stanford University, Stanford, CA, United States, (4)Monterey Bay Aquarium Research Institute, Moss Landing, United States, (5)Stanford University, Portola Valley, CA, United States, (6)Oregon State University, Coastal Oregon Marine Experiment Station, Newport, United States, (7)NOAA Southwest Fisheries Science Center, La Jolla, CA, United States, (8)MBARI, Moss Landing, United States, (9)University of Delaware, School of Marine Science and Policy, Lewes, United States, (10)University of Delaware, Oceanography, Lewes, DE, United States, (11)Monterey Bay Aquarium, CA, United States, (12)Montana State University, CA, United States, (13)NOAA Office of Ocean Exploration and Research, Silver Spring, United States, (14)University of Delaware, Newark, DE, United States
Abstract:
Apex predators are facing an unprecedented worldwide threat from climate change and overexploitation as these species are a source of protein for humans across the planet. Critical to protection of apex predators is an understanding of the oceanic habitats they occupy. How oceanic ecosystems function, from genes to whole organisms, and how the biogeochemical processes drive their productivity and connectivity, are not well understood. The White Shark Café expedition aboard the R/V Falkor (April–May 2018) explored a location far away from any land masses in the North Pacific Subtropical Gyre between the Hawaiian Islands and Baja California. While the region has no obvious surface signatures of elevated productivity, paradoxically it is place where white sharks spend up to 6 months per year. We used satellite tags deployed on sharks in the fall and winter months of 2017–2018, to detect their locations in the Café for an expedition in which real-time sampling was conducted within 24–48h of the appearance of the sharks as indicated by the pop-up positions of satellite tags. We combined shipboard oceanographic and bio-acoustic tools that sampled the epipelagic and mesopelagic ecosystems with eDNA, trawl nets, a remotely operated vehicle, and autonomous vehicle (Saildrone and Slocum Glider) surveys. We also used high-resolution numerical simulations to interpret the observations in the context of the regional circulation and its variability. In this talk we will: 1) describe the oceanographic environment and the epi- and mesopelagic ecosystems of the Café region, and 2) provide results from the tagged white sharks whose diving behaviors in situwere studied in the context of the oceanography to examine why these oceanic waters are vital to their life history.
Back to: From Physics to Predators: Environmental Forcing of Marine Ecosystem Hot Spots I