Sharks enlisted as mobile weather stations to gauge hurricane strength

University of Delaware researchers have begun fitting sharks with satellite-linked sensors to measure the ocean heat that powers hurricanes, a project that could sharpen intensity forecasts for communities from North Carolina to Massachusetts.

The team attaches CTD tags, small devices that record conductivity, temperature and depth, to the dorsal fins of highly migratory species including shortfin mako, blue, smooth hammerhead and juvenile great white sharks. Every time a shark surfaces, the tag transmits a temperature profile to orbiting satellites, building a near-real-time picture of the upper ocean's heat content.

Why sharks beat buoys

Animal-borne sensors have long been used on elephant seals in polar regions, but sharks bring distinct advantages in the North Atlantic. They are abundant, move across the entire hurricane corridor, and surface frequently enough to relay data. Aaron Carlisle, principal investigator and professor in the School of Marine Science and Policy, said the mixed layer, the top 50 to 100 metres of the water column, is the engine of hurricane intensity. Warmer mixed layer equals stronger hurricane, because it holds the heat that feeds the storm.

We are really most interested in the heat content of the top layer of the ocean, which is known as the mixed layer. This is the part of the water column that really drives hurricane intensity, warmer mixed layer equals stronger hurricane.

Tagging like a pit crew

Fieldwork starts each May, when migratory sharks move inshore from winter grounds. Researchers steam 50 to 65 kilometres offshore, deploy baited lines and wait two to three hours for a bite. The tagging itself takes under five minutes, operated "like a pit crew" according to Carlisle. Tags are secured with corrodible links that fall off over time, and every animal receives a health check before release, a stressed shark would not behave naturally, biasing the data.

Caroline Wiernicki, a doctoral candidate leading the sea operations, contrasted the reality with pop-culture caricatures. "It's more like Bob from Accounting, clocking in with the day's temperature profiles before he heads back out," she said. The project is a long way from the Sharknado franchise. "We aren't deploying sharks in and out of waterspouts, yet," Wiernicki joked.

From data to decisions

If the trial succeeds, the shark-borne profiles will feed directly into the oceanographic and atmospheric models that underpin official hurricane forecasts. More accurate intensity predictions would give emergency managers and coastal residents a clearer window for evacuation, sheltering and infrastructure protection as storms approach the eastern seaboard. Carlisle sees a broader dividend: demonstrating that sharks provide a public service could help shift perception away from the Jaws stereotype toward a view of them as essential partners in climate resilience.