Jordan Holder

Document Type

Internship Report

Publication Date

Fall 2018


Lionfish are highly successful invasive species in the Western Atlantic that exhibit habitat and diet generality while inhabiting a wide range of depths. Their adaptability along with culling efforts in certain areas may help determine the severity and spatial distribution of lionfish invasions at the local level. In Dry Tortugas National Park (DRTO), standardized lionfish culling activities have been ongoing since 2013 to protect the park’s diverse array of marine habitats. Until 2017, DRTO had relatively few lionfish compared to other areas of the Florida Keys and Caribbean. However recently, the park has experienced an explosion in the abundance of lionfish. Insights about the spatial distribution of lionfish in the park and the extent to which certain biophysical environmental factors influence their distribution have been made in previous studies, but not in the context of the recent increase in lionfish abundance. Culling data from 2013-2018 was analyzed to determine if any overarching or new patterns in lionfish distribution have emerged. 2016’s data provided equivocal results for the biotic resistance hypothesis, and few conclusions could be drawn from 2013-2016’s data likely due to small sample sizes. 2017-2018’s data indicated that lionfish were most often found on boundary buoys and other artificial structures likely because of the “oasis” phenomenon. Depth analysis of all years’ data suggests that lionfish may have colonized deeper habitats in the region before moving to shallower habitats in the park in more recent years. The results of this study indicate that culling efforts should be focused on areas like boundary buoys where lionfish are highly abundant and humans are more likely to encounter them, and at deeper sites where less is known about their abundance. In addition, such efforts should continue all over the park as they remain the only feasible way to control lionfish populations, therefore ensuring the persistence of native fish populations and coral reef health in the region.


Department: MBE

MPS Track: TME

Location: Dry Tortugas National Park

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