Big Rock Partnership Yields Big Data

Cheers erupt on the crowded docks in Morehead City as a 10-foot long, 449-pound blue marlin is hoisted tail up at the annual Big Rock landing. This June marks the 67th year the fishing tournament has brought competitive anglers to the coast of North Carolina in search of the notoriously hard to catch marlins and generous cash prizes totaling more than $6.3 million.

Among the crowd waiting on the steamy, packed docks are NC State University applied ecologists Paul Rudershausen, Jeffrey Buckel and Ryan Tharp. Each year, they eagerly watch as the 8- to 10-foot blue marlins are weighed and photographed, waiting for the handoff. 

“It’s amazing to get my hands on these giant fish,” says Tharp, a doctoral candidate in fisheries, wildlife and conservation biology. “I can’t wait to get them back to the lab.”

The Big Rock has partnered with NC State for more than 20 years to ensure the prizewinning fish are processed and sent to labs around the United States. The partnership has been crucial for scientists researching the health of the fish and the waters in which they live.

Sea to Lab

Each Big Rock tournament brings in close to 300 game fish in four categories: dolphinfish (mahi-mahi), wahoo, yellowfin tuna — and the anglers’ primary target – blue marlin.

Following the famous weighing and measuring by seasoned weighmaster Randy Gregory, the fish are taken to a nearby tent manned by Tharp, Buckel and Rudershausen. There, they do a cursory processing of the fish, including a quick removal of their stomachs.

“It gets really exciting when you get one with a really full stomach,” Tharp says. “A puffer fish or a baby swordfish — there are some really fun things that come out of the stomach.”

What are they looking for with this dockside dissection? Insight into the diet of the gamefish — and the discovery doesn’t stop there.

Portions of the fish caught are studied by researchers at NC State’s Center for Marine Science and Technology (CMAST). The unique data set spans over 20 years that CMAST has partnered with the Big Rock, creating a long-term time series of fish populations, diets and other biological aspects.

“The entire lab at CMAST helps,” Buckel says. “Paul and Ryan lead the efforts at the dock, but then all the students both in our lab and from other institutions help with obtaining samples and processing the large marlin.”

It may sound labor intensive, but the CMAST researchers are dedicated to the process each year.

“There’s no replacement for being in the field and collecting data yourself,” Rudershausen says. “And our goal is to share our data among other researchers at various geographically disparate institutions to form a powerful, composite picture of how the stocks of any one of these species might be doing.”

Seafood Safety

To date, Rudershausen, Buckel and their colleagues have published myriad studies illuminating fish health and Atlantic ecology for scientists and consumers alike. The Big Rock donates the fish each year, and the Big Rock Foundation has contributed to several research studies at CMAST aimed at understanding important issues for the fishing industry — including mercury content in fish tissue. 

Because blue marlin are a top predator species, there was a concern dating back to the 1970s that their muscle tissue contained a high concentration of mercury, making it unsafe for consumption. CMAST research using data from the Big Rock confirmed that the concentrations of mercury are the highest observed in these fish.

A 2022 study by Rudershausen, Buckel and other collaborators examined the muscle tissue of blue marlin taken from the Big Rock data collections comparing mercury concentrations from 1975-1978 samples and 1998-2021 samples. Their study revealed that mercury levels, although high, actually decreased over this time period, and that the selenium concentrations in Atlantic blue marlin tissue may substantially offset mercury toxicity in human consumers. Other studies have documented the changes in size of the gamefish over time and delved into the diet of the fish, giving a snapshot of what’s happening in the ecosystem in the Atlantic.

From Lab to Lab

Tharp coordinates with other scientists across the country to send the Big Rock data sets and tissue samples to labs studying other aspects of the fish. The hands-on training he’s received as a graduate student is great not only for lab work but also for networking with peer institutions, labs and agencies.

“Scientists know that blue marlin are a hard fish to get your hands on,” Tharp says. “We reach out to other researchers in Texas, Florida and other places who work on this highly migratory species and ask what they may need so we can collect data for them.”

Requests come in for a range of specialties including samples from the ovaries, liver and stomach.

“Applied ecology is science that can solve a specific problem for the public right away.”

“Once we have the fish back at CMAST, we study other parts of the fish,” he says. “For example, the eye lenses help us study their vision, understand what water temperatures and light levels they are best able to see and feed in. It all helps us gain a better understanding of their feeding behavior.”

The results of all this research are fruitful, as are the relationships built between CMAST and other universities and agencies.

“There are a host of fisheries ecology questions that could be asked of this data set,” Rudershausen says. “We make a point to share that data with other researchers around the world.”

“That’s applied ecology,” Tharp says. “We take the skills and knowledge we gain here at NC State and apply them to pressing problems, find the answers and then provide guidance on how to implement them. Applied ecology is science that can solve a specific problem for the public right away.”

This post was originally published in College of Agriculture and Life Sciences News.