Will work for sardines: 20 years of animal-borne ocean observing by Australia’s Integrated Marine Observing System (IMOS) Animal Tagging Facility

The world’s ocean stores ~90% of the excess heat generated by anthropogenic global warming, making sustained ocean observations essential for understanding physical, biological and climate processes. Here, we describe how the Integrated Marine Observing System (IMOS) Animal Tagging Facility, in collaboration with national and international partners, has established a unique animal-borne ocean-observing system. Wide-ranging, deep-diving marine predators provide critical observations from remote and under-sampled regions, particularly the Australian Antarctic sector and tropical northern Australia, complementing traditional observing networks. Since 2004, IMOS Animal Tagging has deployed 1023 instrumented tags on southern elephant (n = 746) and Weddell seals (n = 125), Australian sea lions (n = 50), Australian (n = 8) and New Zealand fur seals (n = 24), and olive ridley (n = 24), green (n = 10) and flatback turtles (n = 16). These deployments have yielded more than 420,000 temperature–salinity–depth profiles spanning the Antarctic to the tropics. The resulting observations have advanced understanding of ocean structure, bathymetry, climate processes and the ecology of wide-ranging marine vertebrates, while providing valuable data to operational oceanography and climate research. Twenty years of sustained observations have demonstrated the importance of long-term, continuous animal-borne data streams as a core component of Australia’s IMOS.