Abstract

Goliath Grouper (Epinephelus itajara), the largest reef fish in the western Atlantic, was once relatively common throughout Florida and the Caribbean. Due to overfishing and loss of juvenile habitat, it is considered critically endangered (Craig 2011). However, under total protection since 1990, population recovery is occurring is the southeastern US. Spawning aggregations are now forming on the shelf off southeast and southwest Florida. Aggregations of 20 to over 100 individuals occur on specific sites, both artificial and natural sites, from late July through October. In an effort to determine the nature of spawning migrations, we implanted 40 adult Goliath Grouper with ultrasonic transmitter tags (VEMCO 69 kHz V16-P coded transmitters) on known spawning sites in 2010 and 2012. Tagged fish were tracked as they moved through the Florida Atlantic Coast Telemetry array of VEMCO VR2 and VR2W ultrasonic receivers. Results indicate that adult Goliath Grouper are relatively sedentary during non-spawning months (mean monthly distance moved = 1.98 km ± 0.6) but moved significantly more prior to aggregation formation in July (18.5 km ± 8.56). Tagged fish moved more during spawning months compared to non-spawning months. Multiple individuals were tracked moving long distances (> 300 km) between residence reefs and spawning sites. Site fidelity to aggregations was high: 84.2% of tagged fish returned to the site of tagging after one year and 77.8% returned after two years. Our study utilizes long-term tagging data of individual fish to aid in understanding the movement patterns of a large reef fish species of special conservation concern.

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