Casting For Clues About Sharks

July 11, 2004

Release from: Al Jones
The Sun Herald (South Mississippi)

OCEAN SPRINGS - The Gulf Coast Research Lab continues its efforts to learn more about the species of fish in South Mississippi, as well as protect our resources.

In the past, intensive research studies have centered around cobia, tripletail and speckled trout. Findings from those studies produced information dealing with seasonal migration routes, spawning habits and feeding traits.

The studies also helped anglers land three of the best fish for table fare the Gulf of Mexico has to offer.

It was a win-win situation for both sides.

Now, the lab is turning its attention to sharks in the Mississippi Sound.

That's right, the creature with sharp and potentially deadly teeth is the center of attention. More than 100 sharks have already been tagged and released in the waters on the inside of the barrier islands.

According to Eric Hoffmayer, a shark biologist at the lab, another 300 to 400 will be tagged in the Sound during the summer.

"It's part of the Sportfish Study that also includes sheepshead and speckled trout," Hoffmayer said. "We have found that the Sound is a nursery for sharks because it's protected waters, it's shallow and it has a lot of food.

"We know there are a lot of newborn and juvenile sharks in the Sound."

In all, Hoffmayer said nine different species of sharks have been found in the Sound, which is blocked off by Horn, Ship and Cat islands. The most common sharks are Atlantic sharpnose, blacktips and finetooth. Others tagged include spinners, hammerheads, bonnets, sandbar and bulls.

Bull sharks, the more aggressive of the Gulf of Mexico sharks, are known to breed in bays and rivers. Although the same holds true in South Mississippi, there is no concern for boaters in the areas.

"We've have found that the bull shark breeds in places like Davis Bayou and the Back Bay of Biloxi where the salinity is zero to 10 parts per thousand," Hoffmayer said. "The bull shark can handle lower salinity levels while others like higher salinity levels.

"We're looking to find out more about the shark movement, how they use the Sound as a nursery and do they go offshore. We have not had any recaptures and that's where we need the help of the fishermen. Without any recaptures, it's hard for us to answer any of these questions."

If someone catches a shark with a tag through the dorsal fin, spend a few moments to get the information off the tag and call the lab at 872-4202. If you don't plan to eat the shark, do not kill it. It can provide valuable information for several years.

"We need to get the word out, and we need help," Hoffmayer said. "A two-percent return rate is good. But most people don't like sharks and don't like to handle sharks. Therefore they cut the line before looking for a tag... .

"We also don't know if the shrimp industry is hampering the tagged fish with their nets. There is so much that we don't know about sharks. We know a lot more about speckled trout than we know about sharks."

One thing the lab has learned is female Atlantic sharpnose sharks stay offshore, which means the Sound is sexually segregated with this species since males and juveniles stay in the Sound. Young sharks are born between May or June and spend the summer growing and maturing in the Sound. They can double in size during that time and are abundant around sandbars, deep dropoffs and reefs around the barrier islands. However, the first cold front of the year forces sharks offshore.

"Why do the females pup outside the Sound?," Hoffmayer said. "Where do they go and why do the newborns come into the Sound? What is their migration pattern?

"We feel like the juveniles follow food into the Sound, but we have no evidence. These are a few questions that we need to find out."

The lab also has plans to publish a booklet that will help fishermen properly ID sharks in the Sound as well as offshore. During the Mississippi Deep Sea Fishing Rodeo, biologists took pictures of sandbar, tigers and bull sharks that will be used in the booklet that will be made available to local anglers and charter boat captains in the near future. For an example, blacktips and spinner sharks are similar, but they are different even though both species have black markings on the tips of their fins.

"Sharks are fascinating animals and we need to find out more about them," Hoffmayer said. "We have plans to go out with a few charter boats and continue the tagging process. The booklet will be a great tool to tell the different species apart and if someone catches a tagged shark, we need them to call us."