Tagging study yields new understanding of sheepshead

With a reputation for a spirited fight at the hook-end of a rod and reel and tasty, sweet, white meat, sheepshead are a choice catch for recreational anglers fishing North Carolina’s coastal waters.

These days, as recreational saltwater fishing regulations have been tightened on some species, particularly flounder, the elusive, not-easy-to-hook sheepshead, with its ever-bizarre, human-like-teeth-filled mouth, is rising in popularity.

Research is underway that may help state fisheries officials better understand just how vulnerable this species might, in the future, be to overfishing.

Lewis Naisbett-Jones, a doctoral candidate at the University of North Carolina Chapel Hill, recently started his second of two field studies seeking to unveil little-known migratory patterns of sheepshead.

The objective: Track sheepshead as they migrate between the summer, when they move inshore, and winter and spring, the time during which the fish travel to offshore habitats.

To do this, Naisbett-Jones utilized a series of tracking systems, including a new model of satellite tag — a costly tracking device at about $1,200 a pop for the cheapest one on the market and one that had to first be tested in a lab.

Pop-Up Satellite Archival Transmitting, or PSAT, tags are, because of their size, typically used to track larger marine animals like sharks, marlin and swordfish. These tags are programed to release from the animal and, upon release, float to the water’s surface and transmit their locations to the Argos satellite network, a worldwide environmental tracking system.

Sheepshead are commonly about 10-20 inches long and typically weigh up to 10 pounds.

Tracking them through the use of pop-up tags meant trying out a new model, this one about 60% smaller than the previous model and one in which very few studies have been conducted since it hit the market.

In June 2020, a lab study was done to determine where to best attach the tag on sheepshead, how a tag affected the fishes’ swimming performance and how much a tag contributed to a sheepshead getting tangled in underwater structures.

Sheepshead have an affinity for underwater structures such as wrecks, rock pilings, jetties and piers — places where they can graze on barnacles and oysters.

By September 2020, the research concluded that the tagging sweet spot on sheepshead is just below the dorsal fin, where the tag can hang off to the side without impeding the fish’s motion or rub against the side of the fish.

The study was finished in time to catch, tag and release 25 sheepshead before their offshore migration in the winter.

“From the data that we’ve acquired thus far, the pattern that we appear to be seeing is the fish don’t seem to be traveling a great distance offshore,” Naisbett-Jones said.

Of those tagged, the sheepshead that swam the farthest from shore went out 18 miles.

The tags were programmed to pop off the fish on certain days this past April, when sheepshead are thought to spawn.

Naisbett-Jones and a team of field technicians plan to tag another 25 sheepshead with pop-up tags once the pound-net fisheries season closes at the end of this month.

“With the satellite tags, the real benefit is telling us the location of the fish as they go offshore,” Naisbett-Jones said. “The acoustic tags, they’re limited to areas where underwater hydrophones are present. What we do is put our hydrophones at the estuaries and determine what time of year, what day and what month the fish are leaving. From our data last year, we’re starting to see a picture of when the fish are leaving.”

The tagged sheepshead began heading offshore in November and some as late as early December, he said.

As of Oct. 13, when Naisbett-Jones spoke with Coastal Review, 14 sheepshead had been tagged with acoustic transmitters.

Sheepshead are also being tagged with $1-apiece plastic tags containing Naisbett-Jones’ contact information. Anglers who catch a sheepshead with one of these tags and call with information – location in which the fish was caught, size, etc. – receive a gift card.

Overall, close to 700 fish have been tagged.

“This whole second year of the project is designed to fill in the gaps and provide us with more data,” Naisbett-Jones said. “The one thing it does go through is the seasonality.”

His project is part of a larger collaboration with researchers from other universities, including North Carolina State University’s Center for Marine Sciences and Technology in Morehead City, where a study is underway to identify major spawning areas of sheepshead, and the abundance of and characteristics of juvenile habitat in North Carolina coastal waters.

“I’m honestly excited we have researchers who want to look into sheepshead because it will help us in the long term,” said Anne Markwith, sheepshead biologist with the North Carolina Division of Marine Fisheries. “It’ll be good for North Carolina.”

The state did not manage recreational sheepshead catch until 2014. Until 2015, there were no size limits on sheepshead.

That limit is no shorter than 10 inches. No more than 10 fish may be caught in one day.

Markwith acknowledged that sheepshead fishing is gaining popularity as regulations have changed for flounder and trout seasons.

“That’s always a concern when you have a species that’s becoming more popular,” she said. “I think right now, all things being equal, it’s a concern in the back of our heads, but it’s not something we’re concerned about right now.”