Climate change alters tiger shark migration routes

The new study, published on 13 January 2022 in the journal Global Change Biologyand conducted by scientists at the University of Miami Rosenstiel School of Marine and Atmospheric Science, revealed that rising ocean temperatures due to climate change have significantly changed the locations and timings of tiger shark migration patterns in the western North Atlantic Ocean. 

Tiger sharks prefer tropical and warm to temperate seas and have historically not been found in the waters off the northeastern coastline of the USA. However, warming ocean temperatures now also make these previously unattractive habitats suitable for the cold-blooded predator. 

Neil Hammerschlag, director of the UM Shark Research and Conservation Program and lead author of the study, explained: “Tiger shark annual migrations have expanded poleward, paralleling rising water temperatures. These results have consequences for tiger shark conservation, since shifts in their movements outside of marine protected areas may leave them more vulnerable to commercial fishing.” 

By analysing animal satellite tracking data, remotely sensed environmental data, habitat modeling, and capture data, the research team found that tiger sharks “in the western North Atlantic between 2010 and 2019 revealed significant annual variability in the geographic extent and timing of their migrations to northern latitudes from ocean warming”, according to the study. 

The researchers argue that, during the last decade which saw high sea-surface temperatures, tiger shark migration routes extended farther poleward by around 250 miles, while the sharks also migrated around 14 days earlier to the waters off the US northeastern coast. 

“Given their role as apex predators, these changes to tiger shark movements may alter predator-prey interactions, leading to ecological imbalances, and more frequent encounters with humans,” added Hammerschlag.