Gut throughput rate and satiation of the invasive Lionfish (Pterois volitans) and its potential impact on an endemic, endangered Labrid fish Halichoeres socialis
Garner, James Graham
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The invasive Indo-Pacific Lionfish Pterois volitans has been recognized as a severe threat to indigenous fish species on Caribbean reefs. Previous studies have identified an extensive variety of Caribbean fishes in the stomachs of lionfish, but few have tried to quantify the impact these invaders could have on endemic or threatened species. The threatened Labrid fish Halichoeres socialis has been identified as the primary component of lionfish diet in Belizean lagoonal reef systems. This study aims to answer two questions: what is the average maximum number of prey-fish a lionfish can consume in one sitting, and at what rate can these lionfish pass a meal of three prey fish completely? To test lionfish satiation, the subjects were fed as many Pseudohemiculter dispar (a commercially available surrogate) as they could eat within a fifteen-minute window. During the digestion rate experiment, lionfish were fed three similarly sized P. dispar and allowed to digest in 3, 6, 9, 12, 15, 19, and 24 hour blocks. From observing prey throughput under near optimal laboratory conditions, the maximum potential impact of lionfish on native populations of Caribbean reef dwelling fishes can be estimated. Given the volume and mass of prey items consumed in this study between 593 and 4658 individual H. socialis could be consumed by a single lionfish in one year. Coupled with further investigation into H. socialis stock numbers, lionfish (P. volitans) could be considered a potentially immanent threat to fishes that exhibit body morphometrics like those of H. socialis at any stage of their life-history.