Straightening the Curve for Florida's Nesting Loggerhead Sea Turtles
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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.
The above graph shows the loggerhead nesting curve for the years between 1988 and 2009, and roughly translates into a forty-one percent nesting decline over the past decade.
While the decline shows some alarming short term trends, it suggests even more alarming long term population trends. The 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
- Disease
- Boat-related Mortality
- Pollution
- 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."
© 2009. Patricia A. Michaels. All rights reserved.