Loggerhead Sea Turtles
Loggerhead Sea Turtles (Caretta caretta), the most common sea turtles found along North American coast lines, continue to experience population stress.
Two recent reports show declines in both eastern and western populations.
Atlantic Loggerheads, the only nesting population, account for the largest percentage of the population.
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Accurate population estimates are difficult to come by, however, the Florida Fish and Wildlife Conservation Commission (FWC) estimates that ninety percent of the Atlantic Loggerhead population nests on Florida beaches.
Recent research examining loggerhead sea turtle nesting habits on Florida beaches suggests an 80% decline by 2017 if actions to straighten the loggerhead nesting curve are not implemented.
Loggerhead sea turtles (Caretta caretta), one of five sea turtle species that nest on Florida beaches, hold the title of most common Florida sea turtle.
Between 1988 and 2009, scientists roughly estimated nesting declines of forty-one percent. Examining the trends, researchers report, "An 80% decline over an even more prolonged period (three generations) is sufficient to warrant the IUCN status of Critically Endangered (IUCN 2001)".
An eighteen year time series analysis of sea turtle nesting activity suggests that nest declines are due largely to declines in the population of reproductive females. The researchers examine eight possible, and potentially inter-related causes of the decline:
- Hatchling Decline
- Direct Take
- Fisheries Bycatch
- Boat-related Mortality
- Global Warming
- Decline in Food Resources
and conclude that both current commercial longline and commercial trawling fishery practices that unintentionally trap and kill mature turtles explains most of the decline.
The report states, "The North Atlantic longline fishery began to expand in the early 1980s...Since this time, longline mortality to oceanic-stage loggerheads has increased to tens of thousands of turtles annually."
Additionally, the authors question the efficacy of the recently revised regulations regarding the use of turtle exclusion devices (TEDs). "Following additional federal TED regulations enacted in 2004, loggerhead mortality has continued at levels (thousands per year) that may have impeded population recovery."
Of the world's seven different sea turtle species, five swim and nest in the Gulf of Mexico.
- Leatherback: Sporadic nesting in Florida and the Mexican Gulf Coast.
- Hawksbill: Nests throughout the Gulf of Mexico.
- Green: Nesting areas in Florida Keys and east Florida.
- Loggerhead: Nests throughout the Gulf of Mexico, with 90% of nesting in Florida, especially southeastern Florida.
- Kemp's Ridley: Most endangered sea turtle with limited nesting on Padre Island National Seashore.
The summer 2010 oil spill in the Gulf of Mexico, the traditional sea turtle nesting season, created population stress, requiring some extraordinary efforts.
The U.S. Fish and Wildlife service considered the plight of the 700 annual turtle nests along the Florida Panhandle and 80 nests along the Alabama coastline, and decided on a massive relocation effort, consisting of collecting tens of thousands of eggs from hundreds of Gulf Coast nests for release along Florida's Atlantic coast.
Most eggs collected came from loggerhead turtle nests, with only a few eggs collected from Kemp's Ridely Turtle nests. Kemp's ridley's hatchlings from the South Padre Island population were released into the Gulf with the hope that the nearby ocean is sufficiently non-oily to give them an opportunity for survival.
Just as there no quick fix to the Gulf oil spill existed, no quick fix for the affected Gulf Coast sea turtle populations exists. It takes anywhere between twenty and twenty five years for hatchlings to mature and return to the natal area to nest.
Translation, it will be a long time before anyone can evaluate the success of these heroic rescue efforts.
North Pacific Loggerheads are the long distance sea turtle migration champions. They are also a smaller, and potentially distinct population, that nests in Japan and forages in the tropical and temperate Pacific waters north of the equator from Japan to the United States.
The Center for Biological Diversity reports on declines of around eighty percent for North Pacific Loggerhead Sea Turtle Populations over the past twenty five years. Long line pelagic fishing practices leads the list of factors influencing population trends, contributing up to sixty thousand loggerhead mortalities per year.
The Center estimates current nesting female populations at less than one thousand. They are petitioning to change the population status from threatened to endangered in order to provide additional tools for aiding species recovery.
A changing climate also poses potential problems for loggerhead populations. For example, fidelity to breeding grounds is a common characteristic for all loggerhead populations. Recent research indicates that increased temperatures (sand temperatures over 33oC) at nesting sites might adversely affect hatchling mortality rates. Sea level rise could also eliminate many traditional nesting areas.
© 2009-2012. Patricia A. Michaels. All rights reserved.