Recruiting Sharks as Climate Trackers

This is a guest post by Diana Udel. This post was originally published on the University of Miami's News and Events page.

University of Miami (UM) shark scientist Neil Hammerschlag knows firsthand that sharks are as mysterious as they are majestic. For over a decade, he has been using sophisticated satellite-tracking tools to follow their every move from space. Thanks to the work of Hammerschlag and others, scientists know that sharks tend to live on the edge – spending a great percentage of their lives around ocean currents like the Gulf Stream and at depths where temperatures change abruptly – in the places where food is plentiful. It wasn’t until a conversation with atmospheric scientist Ben Kirtman, a colleague of Hammerschlag’s at the UM Rosenstiel School of Marine and Atmospheric Science, that the two scientists realized that not only could the data collected from the satellite tags help unravel the mysteries of these important predators that are in decline globally, but could offer climate scientists a better understanding of what communities like Miami and others will face as climate change disrupts weather patterns globally. Sharks offer a unique opportunity for scientists like Kirtman who rely on Earth-orbiting satellites to measure ocean surface temperatures from space or by instruments deployed from ships to measure the water column at a single point in time. Both of which have their limitations in terms of how much data they can collect in remote stretches of the ocean. The satellite tags on sharks offer an additional tool to continuously sample ocean conditions, which is important for Kirtman who needs to understand the shifts in the strength and position of the Gulf Stream since it in turn effects weather and climate along the eastern seaboard—everything from rising sea levels to rainfall. “Information obtained from the shark tags will allow us to go beyond what satellites and stationary buoys can tell us about the state of the Gulf Stream by providing detailed temperature observations with depth, which can then be used to improve forecasting weather and climate from days to decades,” said Kirtman, a professor at the UM Rosenstiel School and director of the UM-based Cooperative Institute for Marine and Atmospheric Studies. The new research alliance between Hammerschlag and Kirtman to use the data from sharks to improve forecast models recently got a boost thanks to a research gift from the technology pioneer Cisco, which funded a pilot study to test the idea. The team is using new tags that have integrated onboard depth and temperature sensors, which continually sample the water and beam this information in near-real time to the scientists. “One of the key goals of Cisco Research is to facilitate new and promising technologies with strong societal, environmental, technological and business impact,” said Ramana Kompella, Head of Cisco Research. “We look forward to learning the results of this study and its impact after completion of the project.” Laura McDonnell, a Ph.D. student at the UM Abess Center for Ecosystem Science and Policy is using the data as part of her dissertation to study how the sharks themselves are responding to changing ocean temperatures and what that will mean for their future conservation and management. Additionally, McDonnell is searching for the best ways to compile and quality control the oceanographic data gathered by the tracked shark for use in weather forecasting models by climate scientists, like Kirtman’s. "This project is an unparalleled opportunity for which we can use these sharks as oceanographers to collect data that will be useful across fields," said McDonnell. “My hope is that this data will help inform conservation of blue sharks, by providing insights into their habitat preferences and their movement under short-term climate variability." Hammerschlag and McDonnell recently spent two-and-a-half days tagging sharks off the coast of Cape Cod to begin the data collection process. They tagged 18 blue and one shortfin mako shark, all large adult males between eight and 11 feet long. While it’s still early to draw any conclusions, they have already collected data on a blue shark diving over 6,000 feet deep (1,848 meters) into waters reaching temperatures of 46 degrees Fahrenheit (7.7 degrees Celsius). “We choose blue and mako sharks since they use a range of depths, from the surface to the deep mesopelagic zone, being able to sample temperatures across a large depth range and then transmit these data at the surface along with their location,” said Hammerschlag, Director of UM’s Shark Research and Conservation Program. “Taking a look at this early data, we are seeing in real-time not only where they go, but the temperatures these sharks experience as they dive to depths, information that is critical to understanding not only the behavior of these animals, but also the ocean’s changing climate” Kirtman is hopeful that the data can be used in his enhanced weather models, including SubX—short for The Subseasonal Experiment, the next frontier of weather forecasting where weather conditions 3-to-4 weeks out will soon be as readily available and reliable as seven-day forecasts. For both Hammerschlag and Kirtman, having more precise seasonal weather forecasts is of personal urgency as South Florida has already begun to experience more frequent and intense hurricanes and flooding from climate change. As scientists continue to unravel the mysteries of sharks, sharks may help scientists unravel the mysteries of Earth’s climate.