Featured Research

from universities, journals, and other organizations

Nesting Gulf of Mexico loggerhead turtles face offshore risks

Date:
July 15, 2013
Source:
United States Geological Survey
Summary:
Threatened loggerhead sea turtles in the northern Gulf of Mexico can travel distances up to several hundred miles and visit offshore habitats between nesting events in a single season, taking them through waters impacted by oil and fishing industries.

Sea turtle. Threatened loggerhead sea turtles in the northern Gulf of Mexico can travel distances up to several hundred miles and visit offshore habitats between nesting events in a single season, taking them through waters impacted by oil and fishing industries.
Credit: StrangerView / Fotolia

Threatened loggerhead sea turtles in the northern Gulf of Mexico can travel distances up to several hundred miles and visit offshore habitats between nesting events in a single season, taking them through waters impacted by oil and fishing industries.

Evidence from a U.S. Geological Survey study challenges the widely-held view that sea turtles remain near one beach throughout the nesting season and suggests the threatened species may require broader habitat protection to recover. The findings also cast new uncertainties on current estimates of the size of the species' Gulf of Mexico subpopulation.

"This is the first study to locate and quantify in-water habitat use by female loggerheads in the Northern Gulf of Mexico subpopulation during their reproductive periods," said lead author Kristen Hart, a USGS research ecologist. "Our tracking results show they depend on a much broader range of habitat during this critical part of their lives than was previously thought to be required."

The study reveals detailed loggerhead movements during "inter-nesting" periods, showing patterns that vary for individual turtles. Generally, this period begins when a female returns from open seas around May and lasts roughly until September. Up until now, efforts to protect the species generally centered on beaches with high nesting activity under the assumption that once turtles had nested on those beaches, they either remained in their immediate vicinity or migrated back out to sea.

"The satellite data and our observations on the ground tell the same story: loggerheads in this subpopulation nest at multiple beaches, sometimes hundreds of miles apart," said Hart. "Some of the females we captured and tagged on beaches in Alabama traveled over 250 miles to nest in Florida, where we recaptured them. Likewise, we also captured some females in Alabama that had previously been tagged at the Florida site in earlier breeding years."

Researchers used the same statistical technique for analyzing their movements that enabled them to pinpoint loggerhead feeding hotspots at sea last year and, more recently, locate Kemp's ridley feeding grounds in the Northern Gulf by differentiating between behavioral modes. They analyzed where 39 adult female sea turtles went after they nested on beaches in Alabama and Florida between 2010 and 2012 to learn where they spent time in the water during the breeding season before migrating back to sea.

"We were surprised to find a lot of variation in their behavior," said co-author and USGS biologist Meg Lamont. "On average, the tagged turtles visited areas about 33 kilometers (20 miles) from shore and moved about 28 kilometers (17 miles) to nest at another beach. Several of them journeyed more than 200 kilometers (124) miles to nest at additional beaches, while others simply cruised back out to sea after the first nest."

The results of the study explain a mystery that had puzzled Lamont, who has 16 years of data from the St. Joseph Peninsula in Florida showing that few of the nesting loggerheads they tagged returned to nest again on the Peninsula. "We didn't know whether they were dying or simply nesting elsewhere," explained Lamont, "Now we know they aren't as faithful to one nesting site as was once thought."

One of the turtles that Lamont tagged in 2002 appeared at Hart's site in Alabama, nearly a decade later. In fact, the researchers saw several turtles nesting both in Alabama and the St. Joseph Peninsula (roughly 250 miles apart) within a period of just two weeks.

"These data show it is not sufficient to just protect habitat around high density nesting beaches -- such as the St. Joseph Peninsula -- because many turtles that nest on the Peninsula use the entire region from the eastern Florida Panhandle to Louisiana," said Lamont.

There could also be fewer female loggerheads nesting in the northern Gulf of Mexico than current estimates suggest because they are calculated using nest numbers. "Our research shows that the same turtle could easily deposit eggs in Alabama and Florida if nests are separated by about 2 weeks," said Hart. "Population numbers based on nest counts may therefore be biased upwards if nests at the two sites were assumed to have come from two different females."

The study also noted that the areas the loggerheads used during the inter-nesting period overlapped with human uses, such as shrimp trawling and oil and gas platforms. A map showing sea turtle habitat use in relation to these activities can be found in the article, "Movements and Habitat-Use of Loggerhead Sea Turtles in the Northern Gulf of Mexico during the Reproductive Period," which was published July 3 in the journal PLOS One.


Story Source:

The above story is based on materials provided by United States Geological Survey. Note: Materials may be edited for content and length.


Journal Reference:

  1. Kristen M. Hart, Margaret M. Lamont, Autumn R. Sartain, Ikuko Fujisaki, Brail S. Stephens. Movements and Habitat-Use of Loggerhead Sea Turtles in the Northern Gulf of Mexico during the Reproductive Period. PLoS ONE, 2013; 8 (7): e66921 DOI: 10.1371/journal.pone.0066921

Cite This Page:

United States Geological Survey. "Nesting Gulf of Mexico loggerhead turtles face offshore risks." ScienceDaily. ScienceDaily, 15 July 2013. <www.sciencedaily.com/releases/2013/07/130715141820.htm>.
United States Geological Survey. (2013, July 15). Nesting Gulf of Mexico loggerhead turtles face offshore risks. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2013/07/130715141820.htm
United States Geological Survey. "Nesting Gulf of Mexico loggerhead turtles face offshore risks." ScienceDaily. www.sciencedaily.com/releases/2013/07/130715141820.htm (accessed July 22, 2014).

Share This




More Plants & Animals News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

San Diego Zoo Welcomes New, Rare Rhino Calf

San Diego Zoo Welcomes New, Rare Rhino Calf

Reuters - US Online Video (July 21, 2014) An endangered black rhino baby is the newest resident at the San Diego Zoo. Sasha Salama reports. Video provided by Reuters
Powered by NewsLook.com
Shark Sightings a Big Catch for Cape Tourism

Shark Sightings a Big Catch for Cape Tourism

AP (July 21, 2014) A rise in shark sightings along the shores of Chatham, Massachusetts is driving a surge of eager vacationers to the beach town looking to catch a glimpse of a great white. (July 21) Video provided by AP
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. Video provided by Newsy
Powered by NewsLook.com
A Centuries' Old British Tradition Is Far from a Swan Song

A Centuries' Old British Tradition Is Far from a Swan Song

AFP (July 19, 2014) As if it weren't enough that the Queen is the Sovereign of the UK and 15 other Commonwealth realms, she is also the owner of all Britain's unmarked swans. Duration: 02:18 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins