Abstract

Lionfish, (Pterois volitans) have been reported at deep depths, below recreational SCUBA diving limits in various locations including Little Cayman. Lionfish density surveys conducted two hours before dusk and repeated one hour later along permanent transects in six sites reveal vertical movement from deep to shallow during crespuscular periods. Acoustic telemetry was employed to further assess horizontal and vertical movement (daily, monthly, seasonal) of lionfish for the first time along a reef wall system. In order to achieve consistent detection of tagged fish, taking into account range test results, a 2000 m gate of 10 receivers was deployed along the northeast reef wall of Little Cayman to passively detect tagged lionfish for 12 months. Thirty adult lionfish (13 female and 17 male) were internally tagged at dusk, between May 22th to July 31st 2017, with Vemco V9P transmitters along the array at depths of 21 to 33 m. In situ tagging was elected to avoid barotrauma stress, which resulted in a number of logistical challenges; low light, current, depth, and sharks. Based on initial receiver downloads and visual surveys, the majority of tag deployments were deemed successful and the lionfish are behaving normally (feeding, swimming, resting with other conspecifics). Irregular movement patterns indicate that some lionfish were preyed upon the night of tagging by a nurse shark, Ginglymostoma cirratum. Preliminary data analysis reveals high tagging site fidelity with individuals remaining within a 300 m range. Daily vertical movement is as high as 30 m in some fish, although variable between individuals. Multiple fish have been recorded as deep as 60 m and one individual as deep as 115 m. A more comprehensive understanding of lionfish movement patterns may allow for targeted removals to be scheduled more effectively.

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