Black groupers (Mycteroperca bonaci) are one of the most commonly landed fish by both recreational and commercial fishermen, yet little is known about their habitat preferences or movements. Previous work trying to determine essential fish habitat has included the collection of data from conventional tagging, presence/absence data from self-contained receivers and acoustic tags, as well as microhabitat data from radio acoustic positioning buoys. While these methods are all valid, the information they provide can be incomplete; in the first two cases providing merely a start and end point, with no direction, and in the last case the methodology is very resource intensive, requiring high maintenance, excellent conditions and constant supervision to track target movement.

In this study, a new method to use self-contained receivers is described which creates an array that can triangulate the position of a tagged fish and track it for months without the need for constant monitoring. The method uses presence/absence data to calculate weighted means, based on the fact that the probability of signal detection is proportional to the distance to the receiver. In an array where the receivers have overlapping detection ranges, the receiver with the most detections will be the one that the transmitter is closest to. In an X- and Y-coordinate system, this leads to position estimates by calculating the mean of the receiver location weighted by the number of receptions. This creates a means to track a tagged fish’s direction through the array.

One such array has been set in place on Conch Reef, Key Largo, around the Aquarius habitat. In collaboration with the PIER Institute and the National Undersea Research Center, the movements of black groupers will be monitored over the reef and its surroundings to answer questions about their diel and seasonal movement patterns and habitat preferences.