Nesting Implications for the Northern Gulf Loggerhead
After the Deepwater Horizon oil spill in the Gulf of Mexico in 2010, a massive response to protect beaches, wetlands, and wildlife occurred. Nonetheless, because of the spill, extensive damage to marine and wildlife habitats were reported and many studies have been conducted to quantify the affects of the oil spill on specific species.
One study in particular which started in the wake of the spill looks at the nesting of loggerhead sea turtles in the northern Gulf and how their feeding areas have been not only affected by the Deepwater Horizon spill, but by commercial fishing operations, and areas used for oil and gas extraction.
The study, which is the largest to date on Northern Gulf loggerheads, examined 59 nesting females, a small and declining subpopulation of loggerheads that is federally classified as threatened.
"With such a large sample of the nesting females, we’re finally getting the big picture of when, where and how females that nest in the northern Gulf of Mexico rely on off-shore waters to survive. This information is critical for halting and reversing their declines," said USGS research ecologist Kristen Hart, the lead author of the study.
All of the turtles tracked in the study remained in the Gulf of Mexico to feed, and a third remained in the northern part of the Gulf.
"These results show how important the Gulf of Mexico is to this group of loggerheads — they stay here throughout the year, not just during the nesting season," said USGS research biologist Meg Lamont, a co-author on the study.
The study also revealed specific parts of the Gulf where females feed and spend most of their time. It is believed that an individual turtle will return to these specific feeding areas throughout her life.
Lamont explains, "People think of nesting beaches as their homes, but they don’t really spend much time there. They only migrate to the nesting beaches to lay eggs. The rest of their adult life is spent foraging at sea."
The next step for USGS scientists Hart and Lamont is to track these nesting Gulf loggerheads long enough to test whether they do indeed re-visit the same feeding areas throughout their life, as they suspect. This would help pinpoint important feeding sites of long-term and high traffic use — in essence, their home ranges.
"Locating long-term feeding areas will really open up new possibilities for the conservation and management of these amazing creatures," said Hart.
The study, "Migration, foraging, and residency patterns for Northern Gulf of Mexico loggerheads: Implications of local threats and international movements" is published in the journal PLOS ONE.
Read more at USGS Newsroom.
Loggerhead turtle image via Shutterstock.