Part 2: Permit Spawning Aggregation Dynamics & Predator Ecology in the Florida Keys

Project Overview

Permit (Trachinotus falcatus) are a popular sportfish species that form seasonal spawning aggregations on natural and artificial reefs throughout the Florida Keys from March through June. While harvest is prohibited from April 1 to July 31 in the region, catch-and-release angling during this time remains common. However, concerns have emerged regarding the sustainability of this practice due to high rates of depredation—when hooked fish are intercepted by predators before release. In response, the Florida Fish and Wildlife Conservation Commission implemented a seasonal fishing closure at Western Dry Rocks (WDR), a site known for elevated depredation mortality.

To better understand the implications of angling pressure and predator presence during the spawning season, researchers from Florida International University and Carleton University are conducting an ongoing study to evaluate the ecology of permit aggregations and predator foraging behavior. This research supports data-driven management efforts and contributes to a broader understanding of fish population dynamics and predator-prey interactions in the region.

This expedition forms one component of that long-term study, employing a combination of video surveys, hook-and-line sampling, acoustic telemetry, and genetic analysis to investigate spawning behaviors, diet, movement patterns, and predator overlap.

Expedition Summary

From May 5 - 18, 2025, The International SeaKeepers Society supported researchers from Florida International University and Carleton University in a field expedition focused on permit (Trachinotus falcatus) spawning aggregations and associated predator interactions in the Lower and Middle Florida Keys aboard SeaKeepers’ Vessel DISCOVERY III.

The research aimed to assess permit ecology and relative abundance, evaluate predator foraging behavior, and monitor movement and connectivity between key spawning sites. Researchers used a combination of methods including video surveys, hook-and-line fishing, and acoustic telemetry to gather data on permit (abundance, size distribution, diet, and genetic connectivity) and potential predators (species presence, abundance, and behavior).

Individual fish were tagged with acoustic transmitters to track movement and residency, and underwater receivers were downloaded and redeployed at known aggregation sites. Biological samples were also collected to support dietary and genetic analyses of permit during the spawning season.

Highlights from the expedition include:

• Video surveys indicated that permit abundance at Western Dry Rocks remained comparable to the previous month. Other aggregating species observed included horse-eye jack and gray snapper.
• Permit sizes ranged from 62 to 80 cm fork length, slightly larger than observed in prior surveys.
• Seven permit were acoustically tagged to monitor their movement across spawning sites.
• Seven underwater acoustic receivers were downloaded and redeployed at key locations in the Lower Keys.
• Nineteen cloacal swabs were collected to analyze fecal DNA for dietary assessment, and 23 fin clips were taken to contribute to ongoing research on genetic connectivity across the greater Caribbean.
• One Caribbean reef shark (Carcharhinus perezi) was acoustically tagged to evaluate predator residency and overlap with spawning aggregations at Western Dry Rocks.
• No other potential depredating shark species were observed or tagged during this expedition.

These findings contribute to a broader effort to inform sustainable fisheries management practices and support ongoing permit and predator monitoring across the Florida Keys.