Did You Ever Wonder What Sea Turtles Do During Hurricanes?

 

Realizing they were sitting on a mountain of data, NOAA Fisheries researchers sifted through location and dive records of satellite-tracked sea turtles, as well as weather buoy data along a stretch of the Mid-Atlantic that had been gathered as a hurricane tracked its way through the sea turtles’ seasonal territory.

As Leah Crowe, a biologist with the team said, “Hurricanes are some of the most intense weather events loggerheads in the mid-Atlantic experience, and we thought it was worth investigating how turtles in our dataset may be influenced by these dramatic environmental changes.”¹ The result is a better understanding of how sea turtles navigate their way through the punishing waters of a hurricane.

The researchers are based at the Northeast Fisheries Science Center at Woods Hole, Massachusetts, and nearby Coonamessett Farm Foundation. They have tagged over 200 loggerhead sea turtles since 2009. In June 2011, they tagged 26 loggerheads along a Mid-Atlantic stretch between Virginia and New Jersey, just two months before Hurricane Irene tore its way up the coast.

The loggerheads had been fitted with sophisticated satellite relay tags that transmitted not only the location and depth of the sea turtles, but also the temperatures of both the sea-surface and ocean depths where the turtles swam. The weather buoy system collects wind direction, speed, gust, significant wave height, swell and wind-wave heights and periods, air temperature, water temperature, and sea level pressure.² On top of that, the team used data from NOAA’s unmanned “autonomous gliders” that are a little fleet of underwater vehicles that can be deployed in the ocean for months at a time, rising and sinking to measure ocean temperature, salinity, and even do acoustic monitoring.³

 

What did the researchers find out about the behavior of the 18 loggerheads who were swimming in the direct path of Hurricane Irene? NOAA summed it up this way:

“Most of the turtles moved northward during the hurricane, aligning themselves with the surface currents — perhaps to conserve energy. Researchers observed longer dive durations after the hurricane for turtles that stayed in their pre-storm foraging areas. Some dives lasted an hour or more, compared with less than 30 minutes for a typical dive before the storm.”¹

“The turtles that left their foraging areas after the hurricane passed moved south earlier than would be expected, based on their normal seasonal movements. This change was also more than a month earlier than the typical seasonal cooling in the water column, which is also when the foraging season for loggerhead turtles ends” along that stretch of the Mid-Atlantic region.¹

Leah Crowe made this observation about the bigger picture for sea turtles and large storms: “The long-term cumulative effects of a changing climate and the increase in intensity of hurricanes and other storms is something that needs to be looked at. Changes in sea turtle movements and behavior can affect abundance estimates and management decisions…This study reminds us that turtles live in a dynamic environment, and we cannot assume their behavior will be consistent throughout space and time.”¹

You can read the complete research paper about this fascinating project here. No surprise that they entitled it, “Riders on the Storm”!⁴

—R.A. Kroft

Sources

¹NOAA Fisheries. Loggerhead Turtles Record a Passing Hurricane. News. 26 August 2020.

²National Data Buoy Center. What is Dial-A-Buoy? NOAA website.

³National Ocean Service. Ocean Gliders: How NOAA Uses Autonomous Technology to Help Predict Hurricane Intensity. NOAA Ocean Podcast, Episode 26.

⁴Crowe LM, Hatch JM, Patel SH, Smolowitz RJ, Haas HL. Riders on the storm: loggerhead sea turtles detect and respond to a major hurricane in the Northwest Atlantic Ocean. Movement Ecology, 2020; 8 (1) DOI: 10.1186/s40462-020-00218-6.

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R.A. Kroft writes about her day-to-day journey in living a smaller, more sustainable life and other topics that interest her.