Warming Waters Cause Sharks to Linger Longer in Northeastern Atlantic Before Heading South
A new study led by researchers from Stony Brook University’s School of Marine and Atmospheric Sciences (SoMAS) has revealed that some migratory shark species in the North Atlantic are delaying their fall migrations due to rising ocean temperatures. The findings, published in Conservation Biology, show that climate-driven changes in sea surface temperatures (SST) are causing sharks to remain in northern waters later into the fall season—by as many as 29 days in some cases.
🌊 Study Highlights:
- Research Duration: 5 years (2018–2022)
- Shark Species Tracked: Sandbar, sand tiger, white, thresher, dusky, and blacktip sharks
- Tracking Method: Acoustic tagging and remote detection
- Key Environmental Factors: Sea surface temperature (SST) and photoperiod (sunlight duration)
🦈 Delayed Shark Migrations Linked to Ocean Warming
The research team tagged and acoustically monitored 155 sharks along the U.S. Atlantic coast. They found that ocean warming significantly influenced the timing of the sharks’ annual southern migration, causing noticeable delays across five species.
Sandbar sharks experienced the greatest median delay in migration—up to 29 days, while sand tiger and white sharks showed minimal delays of about one day. These changes may have implications for shark conservation and marine ecosystem stability.
📍 Why Are Sharks Staying Longer in the North?
According to lead researcher and SoMAS Ph.D. student Maria Manz, both temperature and photoperiod play critical roles in guiding shark migration. Warmer fall temperatures, coupled with longer daylight exposure, appear to encourage sharks to remain in northern regions like the Northeast Atlantic and the New York Bight for extended periods before heading south to warmer waters along the Carolinas and Florida.
“Our model predictions suggest that future ocean warming could further delay southern shark migrations. There are also species-specific and regional differences in how sharks respond to environmental changes,” said Manz.
🔍 How Were Sharks Tracked?
The study employed acoustic tagging, a passive and non-invasive method. Each shark was fitted with a uniquely coded tag that emitted signals detectable by underwater receivers placed along the Atlantic seafloor. These receivers recorded the movement patterns of sharks within a 900-meter range, allowing researchers to model migratory behaviors over time.
🗺️ Defining ‘Southern Migration’
The researchers defined southern migration as the final annual detection of a shark within its latitudinal movement range along the U.S. Atlantic shelf. Movement data were analyzed across five specific oceanic zones along the East Coast.
🔬 Conservation and Ecosystem Impacts
As sharks delay their migrations, they may interact differently with regional prey and predator species, potentially altering ecological balances. The study emphasizes that understanding these patterns is critical for developing effective shark conservation strategies in a rapidly changing climate.
📚 Research Citation:
Manz, M.H., Frisk, M.G., Cerrato, R.M., Shipley, O.N., et al. (2025). Predictions of southern migration timing in coastal sharks under future ocean warming. Conservation Biology. DOI: 10.1111/cobi.70080