Jack Crevalle: Tag, Track & Learn

Feature Photo Credit: Scientific Anglers Team

At the heart of the Jack Project is a simple but powerful goal:
Shine a light on the jack species that anglers know well, but science and management often overlook. To better understand their movement, behavior and connectivity of this species, we’re putting boots on the deck and tech in the water. Our game plan is built on acoustic telemetry, but before we can follow these fish around the ocean, we have to catch and tag them.

---

The Tagging Process

Our work starts on the water, working side-by-side with charter captains. We have a small, select team of guides from all major stakeholder states, from South Carolina to Texas. Our guides keep the pulse of the fishery, knowing when, where and how the fish are behaving to maximize our efficiency. From there, the process goes something like this:

1. Catch & Assess:
   A jack is caught and quickly brought to the boat. A clean hook set and minimal fight times are paramount to this process. Guides and researchers work together to measure its length, assess its condition, and determine if it’s a viable candidate for tagging.
2. Deploying Tags:
   A small incision is made in the abdominal cavity, and an acoustic transmitter is inserted. There is a strict series of steps followed by the team to ensure this process is clean and efficient. This tag sends out a unique sound signal—a kind of underwater “ping.” We’ll discuss how those pings are recorded in the next section of this blog.
3. Release & Record:
   After stapling the incision, the fish is revived and safely released. We note GPS coordinates and environmental data like water temperature and depth, as well as behavioral data. If two fish were tagged from the school, that is noted to see how schooling/migratory behavior is affected by catch and release.

This process is designed to be as minimally invasive and as fast as possible, prioritizing the health of the fish and the quality of the data.

---

How Do We Track These Fish?

Once released, the acoustic tags begin to do their work. Each tag emits a coded signal at a set interval. Underwater acoustic receivers placed along the coast can pick up that signal. These receivers are stationary listening devices that dozens of academic and agency partners maintain. What makes this work so exciting is the cooperative network behind it:

• Shared Infrastructure:
  Researchers from Maine to the Gulf of Mexico maintain receiver arrays—anchored to the seafloor or attached to fixed structures like buoys.
• Data Collaboration:
  When a tagged jack swims past a receiver, that “ping” is logged and time-stamped. These detection data are uploaded to shared databases where researchers can access and compare movement patterns, migration timing, and habitat use. For example, a research focused on manta ray or grouper movements may say “hey, we found two of your jacks over here last week!”
• Long-Term Tracking:
  The tags in The Jack Project have a 5+ year battery life, hopefully providing years of insight into where these fish travel, how far they go, and if they return to specific sites.

Collaborative tagging efforts are one of the most cost-effective ways to fill the massive data gaps that currently surround understudied species like jack crevalle—and they are only possible when scientists, anglers, and organizations like ASGA team up for the greater good.