A tagging study helps to better understand the sheep’s head


UNC doctoral student Lewis Nasibett-Jones releases a sheep’s head in coastal waters outside the Morehead City Institute of Marine Sciences. Naisbett-Jones’ research focuses on the movement and migration patterns of these fish to inform the state’s fisheries management practices. Photo: Megan May / UNC Research

Known for fiery rod-and-reel combat and savory, sweet white meat, Mutton’s Head is a prime catch for recreational anglers fishing the North Carolina coastal waters.

Nowadays, as regulations on saltwater recreational fishing have been tightened for some species, especially plaice, the elusive and difficult-to-hang sheep’s head, with its ever-strange mouth filled with human teeth, is gaining in popularity. popularity.

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

Lewis Naisbett-Jones, a doctoral student at the University of North Carolina Chapel Hill, recently began his second of two field studies aimed at uncovering the little-known migratory patterns of the sheep’s head.

The objective: to follow the sheep during their migration between the summer, when they move towards the coasts, and the winter and the spring, when the fish move towards the offshore habitats.

To do this, Naisbett-Jones used a series of tracking systems, including a new model of satellite beacon – an expensive tracking device at around $ 1,200 a piece for the cheapest on the market and which first had to be laboratory tested.

Pop-Up Satellite Archival Transmitting, or PSAT, beacons are, due to their size, typically used to track larger marine animals like sharks, marlin, and swordfish. These beacons are programmed to be released from the animal and, once released, float on the surface of the water and transmit their position to the Argos satellite network, a global environmental monitoring system.

Working in the lab, Naisbett-Jones attaches a pop-up satellite tag to a large female sheep’s head. The mark is scheduled to be released and float to the surface in April when the fish are expected to spawn. Once on the surface, the beacon can send water temperature and location data to a satellite, at which point Naisbett-Jones can download this information. Photo: Megan May / UNC Research

Sheep heads are typically around 10 to 20 inches long and typically weigh up to 10 pounds.

Tracking them through the use of contextual beacons meant trying out a new model, this one about 60% smaller than the previous model and in which very little research has been done since it launched in the market.

In June 2020, a laboratory study was performed to determine where best to attach the tag on the sheep’s head, how a tag affected swimming performance of fish, and to what extent a tag contributed to the entanglement of a sheep’s head in underwater structures.

Sheepshead has an affinity for underwater structures such as wrecks, rock piles, piers, and jetties – places where they can graze on barnacles and oysters.

In September 2020, research concluded that the ideal marking point on the sheep’s head is just below the dorsal fin, where the mark can hang to the side without impeding the movement of the fish or rubbing against the side of the fish. .

The study was completed in time to capture, mark and release 25 sheep before their migration offshore in winter.

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

Of those marked, the sheep that swam the furthest from shore came out 18 miles.

The tags were scheduled to take out fish on certain days last April when the sheep’s head is believed to be breeding.

Naisbett-Jones and a team of field technicians plan to mark 25 more sheep with pop-up tags once the net fishing season is over at the end of this month.

“With satellite beacons, the real benefit is telling us where the fish are when they go out to sea,” Naisbett-Jones said. “Acoustic beacons, they are limited to areas where underwater hydrophones are present. What we do is put our hydrophones in the estuaries and determine what time of year, what day and what month the fish are leaving. Based on our data from last year, we’re starting to see a picture of the fish leaving. “

Naisbett-Jones has a satellite beacon used in his research. For years, these beacons have been used only to track large land or marine species. Recently, however, they have been reduced and at lower cost – from around $ 5,000 to $ 1,200 – giving researchers the ability to collect data on smaller species. Photo: Megan May / UNC Research

The tagged sheep head started heading offshore in November and some as late as early December, he said.

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

Sheepshead is also tagged with plastic $ 1 each containing contact details for Naisbett-Jones. Fishermen who catch a sheep’s head with one of these tags and call with information – where the fish was caught, size, etc. – receive a gift card.

In total, nearly 700 fish were 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 only thing he goes through is seasonality. “

His project is part of a larger collaboration with researchers at other universities, including the Center for Marine Sciences and Technology at North Carolina State University in Morehead City, where a study is underway to identify the main sheep’s head spawning areas, as well as the abundance and characteristics of juveniles. habitat in the coastal waters of North Carolina.

“Honestly, I am delighted that researchers are interested in looking at the sheep’s head because it will help us in the long run,” said Anne Markwith, sheep head biologist with the North Carolina Marine Fisheries Division. “It will be good for North Carolina.”

The state did not manage recreational catches of sheep heads until 2014. Until 2015, there was no size limit for the head of sheep.

This limit is not less than 10 inches. No more than 10 fish can be caught in a day.

Markwith acknowledged that sheep’s head fishing is growing in popularity as regulations have changed for the plaice and trout seasons.

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


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