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Data Czar Deliberations

I was recently asked if relocating nests was a good "thing" and are these nests as successful as nests left in-situ. I dug into that question again. I looked at the data for % Emergence Success for the last 10 years (2013-2022). Why emergence success and not hatch success? Well, to me Emergence Success is the key as it looks at how many hatchlings made it out of the nest. Hatch Success looks only at hatchlings that left the egg shell - in other words, it includes hatchlings found dead in the nest. So I wanted to look at how many made it out and hopefully into the ocean. First of all, Emergence Success is almost always lower than Hatch Success by a few % points because of the hatchlings found dead in the nest. The dead hatchlings count in Hatch Success but not in Emergence Success (ES). So ES sort of takes the whole nesting process, including relocation activities and sand compaction, into account. So what did we find (see the attached chart). Over the 10-years, relocated nests had a higher ES% (higher is better) than in-situ nests by about 6% points. So relocation of nests does NOT appear to be detrimental to the sea turtle nesting and survival, in fact it appears, on the surface, to be beneficial. Over that same 10-year period, relocated nests outperformed in-situ nests (on %ES) in 7 of those years. Only in 2017, 20 and 22 did in-situ nests do better. Why do relocated nests do better? Look at the large difference between relocated and in-situ nests in 2018 with relocated nests doing much better. In looking at the detailed report, there were a number of washovers of nests that year, primarily in-situ nests, during the critical incubation and hatchling period. The nests basically "drowned" during major storms. In-situ nests are more susceptible to washovers and flooding than relocated nests based because we purposely move nests to higher and potentially safer ground. Remember the primary driver to move or relocate nests is to avoid washovers and improve the chances of survival. In 2020, in-situ nests had a better % ES. This one is hard to explain, but I believe it is due the fact that this was the first full year after beach renourishment. And as Buddy points out there a rainfall event that dumped 13 inch of rain in 24 hours, flooding most of the roads, beaches on Hunting Island during the incubation period. There were low points in the new beach up close or near the man-made dunes. And in fact, in Zone 2 there was a lagoon developing behind the dune from fresh water that was "piling up" as it tried to drain away. That water seeped into the dunes and made some of them very soggy. That lagoon is now gone as an opening was cut in the dune to let the water drain away. We were moving nests that year to the dune or right in-front of the new dunes, not realizing the dune was going to be soggy or that the beach low points really existed and would eventually collect rain and salt water. 2020 overall was a very bad year whether it was ES or Hatch success, or relocated or insitu nests. This was the lowest year for hatch success overall I have witnessed. Only the nests, insitu or relocated, on the very top of dunes survived. Lesson learned unfortunately. If you have a query, please let me know




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