Local fishermen partner with scientists to protect New England’s iconic fish

Chasing Cod to Keep Them Safe

By ecoRI.org News staff

Jeff Kneebone releases a tagged Atlantic cod into Massachusetts 

Bay while performing research aboard the Yankee Rose recently. 

(John Clarke Russ/The Nature Conservancy photos)

SCITUATE — Local fishermen have always known that cod return to the waters off the South Shore to breed this time every year — clustering in large numbers, spawning and providing our best hope of a future for healthy cod populations.

Now, scientists and fishermen are working together to use an “E-Z Pass for fish” to gather data about fish behavior, and to better protect this iconic species and the communities that depend upon it.

Concerned commercial fishermen from the South Shore sought out scientists from The Nature Conservancy, the Massachusetts Department of Fish & Game’s Division of Marine Fisheries, the University of Massachusetts Dartmouth and the National Oceanic and Atmospheric Administration (NOAA) to help them map out exactly when and where spawning occurs, with the goal of protecting local cod during their spawning season.

“South Shore fishermen approached us to help protect these spawning cod with the future of the fishery in mind, and the collaborating researchers jumped at the chance to work closely with them,” said Chris McGuire of The Nature Conservancy in Massachusetts.

During the next few weeks, local fishermen, working with scientists, will hook spawning cod, implant electronic tags and then release the fish back into the sea. The project’s goal is to protect these local fish during spawning, as they are particularly vulnerable during this period. 

Local fishermen are now seeing cod only during their spawning season in the late fall and early winter, whereas they used to be abundant for much of the year, said Frank Mirarchi, who has fished from Scituate Harbor since 1962 and has personally witnessed a decline in cod abundance. 

Because such factors as warmer sea water and increased predation have made the fishing business on the South Shore ever more uncertain, his son has recently made the difficult choice to leave the fishery industry, he said. 

“We hope to provide these fish with protection while they’re vulnerable,” Mirarchi said. “The expectation is that we can provide discrete, small protected areas which will not be disruptive to fishing, while helping the cod stock to recover.”

Each electronic tag, once deployed, emits a coded sound roughly once a minute for up to six years, a signal that’s recorded whenever the fish passes within range of a network of receivers deployed on the sea floor. Each tag has a unique acoustic signature, allowing scientists to track individual fish using the more than 3 million pings each tag will emit over its lifetime.

“It is sort of like an E-ZPass for fish,” McGuire said.

This information allows researchers to visualize the behavior of each fish while on the spawning grounds, and exactly when they leave which is needed for defining a seasonal closure and also to better understand spawning behavior, McGuire explained.

“The tagging technology has been an excellent tool for studying spawning cod in Massachusetts Bay and our improved understanding of their behavior will help to inform stock assessment and fishery management for rebuilding the resource and the fishery,” said Doug Zemeckis, a Ph.D. student at UMass-Dartmouth.

“Cooperative research like this effort involving fishermen, government agencies and environmental organizations is vital to improving fisheries management for species like Atlantic cod,” said Massachusetts Department of Fish & Game Commissioner Mary Griffin.

Researchers are also recording the grunting sounds that male cod make to defend their territories and to attract females. Underwater microphones, deployed by NOAA, will record fish vocalizations, which can be used to characterize the timing of the winter spawning period, as well as the relative abundance when compared to past data.

Federal researchers from the Northeast Fisheries Science Center and the Stellwagen Bank National Marine Sanctuary use this same equipment to monitor whales.

“Passive acoustics — or listening for cod sounds — is an ideal way to monitor the seasonal presence and persistence of cod spawning aggregations over long time periods,” said Sophie Van Parjis, of the Passive Acoustic Research Group at NOAA’s Northeast Fisheries Science Center in Woods Hole.

“Passive acoustic recorders can listen continuously for up to six months, regardless of weather conditions. We are currently looking at historical data for this area (2004-2014), to look at how the presence of cod has changed over time. In addition, our passive acoustic recordings will help define the start and end of the spawning season, so we can more accurately define the time period needed to protect these aggregations.”

Atlantic cod is central to Massachusetts history — fishing helped build the state’s economy and remains an important industry. However, the cod population has seen steep declines in the past 20 years, and despite drastic measures to reduce fishing pressure, remains at historic lows. This year, local fishermen faced a devastating 78 percent cut in the Gulf of Maine cod annual catch limit, which has severely impacted fishermen across the Bay State.

Ultimately, fishermen and scientists will bring the spawning data to the New England Fisheries Management Council to inform future management decisions designed to care for this valuable cod population.

“This groundbreaking, collaborative effort between commercial fishermen, Massachusetts scientists and the environmental advocacy community is a perfect example of a forward-thinking partnership that is needed to bring critical answers to the groundfish industry,” said Rep. Bill Keating, D-Mass.