Part 1: Permit Spawning Aggregation Dynamics & Predator Ecology in the Florida Keys

Program Overview

Each spring, permit (Trachinotus falcatus) form spawning aggregations on natural and artificial reefs throughout the Florida Keys, particularly around the full moons from March through June. In recent years, catch-and-release angling for permit during this period has become increasingly popular. While harvest is prohibited between April 1 and July 31, high levels of depredation (when predators such as sharks remove hooked fish) have raised concerns about the sustainability of this practice.

To mitigate these impacts, the Florida Fish and Wildlife Conservation Commission implemented a seasonal closure at Western Dry Rocks (WDR), a known aggregation site with historically high depredation rates.

This ongoing research project aims to evaluate permit spawning dynamics, fishing pressure, and predator interactions across multiple sites in the Florida Keys. The data collected will help inform future management decisions to ensure the long-term sustainability of the permit fishery.

Expedition Summary

From April 6 - 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 II.

The research aimed to assess the ecology and relative abundance of permit, monitor fishing pressure and depredation mortality, and evaluate predator foraging behavior at known aggregation sites. Researchers used a combination of methods including video surveys and hook-and-line fishing to gather data on permit (abundance, size distribution, diet, and genetic connectivity) and potential predators (species presence, abundance, and behavior).

To track permit movement and residency, individual fish were tagged with acoustic transmitters, and underwater receivers were deployed at known aggregation sites. Researchers also collected observational data on fishing activity, such as the number of boats present, time spent fishing, and instances of hooked permit being taken by predators.

Highlights from the expedition include:

• Initial video survey results showed the highest permit abundance at Western Dry Rocks in the Lower
  Keys. In the Middle Keys, permit schools were more variable and sometimes mixed with other jack
  species, including crevalle and horse-eye jacks.
• Permit sizes ranged from 53 to 77 cm fork length, with an average around 65 cm, consistent with
  previous years.
• Thirty-three permit were acoustically tagged, with 20 in the Middle Keys and 13 in the Lower Keys. Two
  acoustic receivers in the Middle Keys were also downloaded and redeployed to support ongoing
  tracking efforts.
• Researchers collected 29 cloacal swabs to analyze fecal DNA for diet assessment and 33 fin clips to
  study genetic connectivity among permit populations across Florida.
• No permit fishing was observed at Western Dry Rocks, where seasonal closures were in effect.
  However, targeted permit fishing was documented at sites in the Middle Keys. Most anglers spent one
  to two hours on-site, and 20 angling events were recorded, with 10 fish landed.
• Several shark species were observed across study sites, including great hammerhead (n=2), bull shark
  (n=1), and Caribbean reef shark (n=3).