Management of Hatchling Misorientation on Urban Beaches of Broward County, Florida: Effects of Lighting Ordinance and the Learning Curve
28th Annual Symposium on Sea Turtle Biology and Conservation, Loreto, Mexico, January 22-26, 2008
Prior to the 2006 nesting season, a comprehensive nest relocation program in Broward County, FL was used as a management strategy to protect sea turtle hatchlings from the disorienting effects of artificial lighting. Twenty-five years of nesting data suggest that conservation by means of nest relocation resulted in reduced nest productivity. The resultant loss in the number of hatchlings reaching the water compared to those nests left in situ prompted the Florida Fish and Wildlife Conservation Commission to alter permit conditions to exclude the use of hatcheries as a management option beginning in 2006. The designation of much larger areas considered dark enough to receive relocated nests and to leave nests in situ meant fewer nests were relocated and relocated nests were moved shorter distances. As more nests were left in situ during the 2006 and 2007 nesting seasons, the importance of light management increased throughout the County. We compared the estimated total numbers of disoriented hatchlings and the numbers of disoriented hatchlings that were unaccounted for (presumed dead) in 2006 with 2007. Since disorientation data for 2007 is only available up to September 8, 2007, the time of this writing, data after September 8 for the 2006 nesting season was not included in the following comparisons. Evaluation of 2006 disorientation reports suggested that between 14,461 and 16,897 hatchlings disoriented throughout the County. While the number of disorientation events decreased in 2007, the total number of disoriented hatchlings increased by about one percent, and ranged from 14,547 to 16,987. However, the estimated numbers of disoriented turtles reaching the water in 2007 was from 1,718 to 2,159 greater than in 2006. Concurrently, it is estimated that this resulted in a decrease in the number of missing hatchlings in 2007, between 1,632 and 2,069 compared to 2006. County wide, the incidence of disoriented hatchlings found dead on the road decreased by 68%. Reports in 2006 from the highly urbanized municipalities including the Fort Lauderdale strip, where half of the nests were caged, indicated that the number of disoriented hatchlings ranged between 1,501 and 1,621 while 2007 data show that half as many hatchlings (between 672 and 722) disoriented. Furthermore, evaluation of incidents occurring in areas of Lauderdale by the Sea in 2007 indicate that the minimum and maximum estimates of total disoriented hatchlings that reached the water increased by 755 to 910, representing increases of 65% and 54% from 2006, respectively. Therefore, minimum and maximum estimates of the number of missing, disoriented hatchlings decreased from 2006 to 2007 by 38% and 43%, respectively. Reductions in the number of lost disoriented hatchlings documented in 2007 may be attributed to the combined efforts of the enforcement of coastal lighting ordinances and the application of experience gained from the previous nesting season. With the knowledge gained from 2006, surveyors were able to avoid placement of relocated nests in areas known to have recurring lighting problems.
Blackburn, Michele V.; Burney, Curtis M.; and Fisher, Louis, "Management of Hatchling Misorientation on Urban Beaches of Broward County, Florida: Effects of Lighting Ordinance and the Learning Curve" (2008). Oceanography Faculty Proceedings, Presentations, Speeches, Lectures. 302.
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