Permit Spawning Aggregation Dynamics
SeaKeepers' Vessel DISCOVERY
Key West/Marathon Key, Florida
April 3-15, 2023
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.
Duration of Project
2018 - 2024
From April 3rd - 15th, 2023, The International SeaKeepers Society assisted researchers from Florida International University, supported by Bonefish & Tarpon Trust, in conducting research on permit (Trachinotus falcatus) spawning aggregations 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, where depredation mortality has been historically high, to protect permit and other species that aggregate here. To evaluate the efficacy of this closure and monitor other fished aggregation sites throughout the Florida Keys, we used a combination of active acoustics (multi-beam imaging sonar), video (360° and line-cameras), and hook-and-line fishing surveys to collect data on permit school size and individual size. 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 were also collected.
Lastly, as an added method for researching the movements of permit throughout different geographic areas, acoustic tags were implanted in each fish caught. These tags emit a unique frequency which is then heard by acoustic receiver arrays. These receivers which log the data, are then retrieved and downloaded.
Highlights from data collected on this trip:
The data collected on this trip will be used to assess seasonal and annual variation in permit spawning aggregation density and distribution across several sites in the Lower and Middle Florida Keys. Moreover, 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.The acoustic tagging efforts will also build upon previous telemetry data to assess residency and movements across habitats and aggregation sites in the Florida Keys.