Part 2: Permit Spawning Aggregation Dynamics & Predator Ecology Research


SeaKeepers' Vessel DISCOVERY
Lower Keys, Florida
April 15 - 26, 2024

Program Overview

The purpose of this research is to monitor permit spawning aggregations on natural and artificial reefs in the Florida Keys, collecting data on aggregation size and distribution, fishing pressure, and depredation mortality.


The data collected on this trip will be used to assess seasonal and annual variation in permit school size and distribution at prominent spawning aggregations in the Florida Keys. The observational data from this trip will be used to quantify recreational fishing effort and associated depredation rates at openly fished sites, which is critical in understanding the extent of depredation mortality and its effect on permit spawning aggregation dynamics. Acoustic telemetry data will also shed insight onto the movement ecology and residency of both permit and their predators.

Expedition Summary

On April 15 - 26, 2024, The International SeaKeepers Society assisted researchers from Florida International University and Carleton University in conducting research on permit (Trachinotus falcatus) spawning aggregations and associated predators in the Lower and Middle Florida Keys. Permit aggregate on natural and artificial reefs in the Keys surrounding the full moons from March through June each year. Catch-and-release angling for permit during their spawning season has become a popular sport fishery for many anglers, and, although not inherently detrimental to the fishery since permit harvest is prohibited between April 1 and July 31 throughout the Florida Keys, depredation (i.e., the removal of hooked fish by a predator) has produced a high level of concern regarding the sustainability of this practice. As a result, Florida Fish and Wildlife Conservation Commission implemented a seasonal fishing closure from April 1 – July 31 each year at Western Dry Rocks (WDR), where depredation mortality has been historically high, to protect permit and other species that aggregate here.

To evaluate the size and ecology of permit aggregations, monitor fishing pressure and depredation mortality, and assess predator foraging ecology of these aggregations in the Florida Keys we use a combination of methods. Video (unbaited and line-mounted cameras) and hook-and-line fishing surveys are conducted to gather data on predator occurrence, permit abundance, individual fish size, diet and genetics. The movement and residency of permit are monitored using acoustic telemetry, where individual fish are tagged and underwater receivers are deployed at known aggregation sites. Observational data on fishing pressure (i.e. number of fishing boats, time spent fishing) and depredation rates (i.e. number of angled permit lost to sharks) at openly fished sites is also collected. Lastly, we assess shark movements and foraging ecology through acoustic tagging and biological sampling methods.

Some highlights from data collected on this trip:
• Initial results from the video data suggest that permit abundance ranged from several hundred to over one thousand individuals at WDR in the Lower Keys. In the Middle Keys, permit schools were more variable in abundance and distribution and occasionally mixed with other species of jack (i.e., horse-eye, crevalle).
• The range of permit sizes (56-82 cm fork length) was similar to previous seasons (average 67 cm fork length).
• Twelve permit in the Middle Keys were acoustically tagged and seven receivers were downloaded and re-deployed in the Lower Keys, as part of ongoing efforts to assess movement and connectivity between spawning sites.
• 57 cloacal swabs were collected, which will be used to analyze permit fecal DNA and assess their diet during the spawning season, and 76 fin clips from permit, which will contribute to an assessment of permit genetic connectivity throughout Florida.
• While permit fishing at Western Dry Rocks (Lower Keys) was closed, researchers observed increased fishing pressure in the Middle Keys relative to the previous month. Most fishers spent <1 hr on site looking for permit, and we documented 10 hookups, including at least two probable depredations. • Several shark species were observed, including great hammerhead (Sphyrna mokarran; min. 2 individuals), and we acoustically tagged Caribbean reef (Carcharhinus perezi; n=1), lemon (Negaprion brevirostris; n=1), and tiger (Galeocerdo cuvier; n=1) sharks in the Lower Keys.


Florida Keys

Duration of Project

2018 - 2024

Research Team

  • Ben Binder, PhD
  • Kirk Gastrich, MSc
  • Gina Clementi, MSc
  • Jessica Robichaud, MSc
  • Luc LaRochelle, MSc
  • Capt. Aubri Keith
  • Chase Schaffhauser, Undergraduate Student (FIU)


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