How Worm Harvesters Are Helping Acadia Understand Its Declining Coastal Fisheries

Acadia National Park is working with local communities to study the park’s changing coastal environment. There’s a lot at stake.

By Hannah Webber and Abe Miller-Rushing

Woman with hip waders and safety vest holds up a long worm while standing on a beach with marine worm
Scientists in Parks intern Maya Chari holding up a milky ribbon worm, a predator of bloodworms and sandworms.

Image © Schoodic Institute / Hannah Webber

Whether you’re a person, a marine worm, or a clam, making a living at sea along the shores of Acadia National Park is hard work. And a changing climate has made it even harder. Marine worm populations in and around Acadia—like their clam counterparts—have declined steeply in recent years. The declines are a symptom of changing coastal ecosystems, and they pose extreme challenges for people who rely on those ecosystems for their livelihoods. Acadia scientists are working with local communities to understand how and why the park’s coastal worm fisheries are changing. The generational and professional knowledge community members bring to the table is critical.

A Humble Linchpin

You’ve probably heard of clam harvesting, especially if you’re a fan of clam chowder or steamed clams. But unless you’re an angler, you may not know that marine worms, which recreational anglers use for bait, are also harvested. Maine is one of the few states in the U.S. with an active marine worm fishery, primarily for bloodworms (Glycera dibranchiata) and sandworms (Alitta virens or Neanthes virens). Just like clammers, worm harvesters dig for marine worms in intertidal mudflats during low tides.

Like clams, marine worms are one of the biggest fisheries in Maine. In 2022, Maine worm harvesters brought in 6.6 million dollars in revenue for bloodworms and sandworms combined. Worm harvesters work independently or in small groups and shift the locations of their harvests to follow movements and changes in worm abundance. Oral histories suggest Maine’s modern worm fishery dates to the early 1900s, when there were shortages of bait worms elsewhere on the East Coast.

“We knew the biodiversity in the soft-bottom intertidal areas in the park was changing. But we didn’t know exactly how or why.

The industry peaked in the 1970s, with about 1.8 million pounds of worms harvested in 1973, but it has come upon hard times in recent years. Only about 400,000 pounds were harvested in 2022. That year, there were 723 active worm harvesters in Maine, down from 3,383 in 2008, the most recent year with harvester data. Congress passed legislation in 2019 to formally allow traditional worm and shellfish harvesting in Acadia National Park’s mudflats. These practices had been informally happening in the park’s mudflats for many years.

In addition to their economic and cultural importance, marine worms—like clams—are important indicators of coastal ecosystem health. Shifts in their populations can reflect changes in sediment chemistry, the arrival of invasive predators like green crabs, or changes in marine food webs. Harvesters have deep knowledge of the mudflats. They see these changes as they happen. That’s why Acadia National Park scientists, students, and managers are working with harvesters to understand what’s causing declines in these fisheries.

“We knew the biodiversity in the soft-bottom intertidal areas in the park was changing,” said Rebecca Cole-Will, the park’s Resource Management Program manager. “But we didn’t know exactly how or why. We could have simply repeated biodiversity surveys done in the past, but we would have missed the first-hand knowledge that the harvesters have and the opportunity to work collaboratively with them. We had a lot to gain by working together.”

Hand holds a colorful worm against a deep green background
A sandworm (Alitta virens)

Image © Jennifer Booher

Local Clues Inform Data Digs

In summer 2022, student interns and staff working for the National Park Service and the Schoodic Institute began to assess biodiversity across soft-bottom intertidal areas in Acadia in response to concerns from scientists, managers, and community members. They met with researchers and local marine worm harvesters to discuss the best approach to take. The harvesters had little background in conventional science but decades of practical knowledge. They shared crucial insights about why populations differed from place to place and year to year.

“It could be people putting pesticides on their lawns or a warming ocean. Or it could be the green crabs or more rain.”

Local harvester Fred Johnson had been fishing for worms commercially since he was seven years old. He knew that some places continued to be productive, but others were spotty, and some that once had great harvests had dwindled to nothing. “It could be people putting pesticides on their lawns or a warming ocean,” Johnson said. “Or it could be the green crabs or more rain.” He added, “On top of mudflat-to-mudflat changes, there haven’t been any worms settling in the eastern part of the park in the last 20 years.” The students worked with scientists and park managers to revise their study design, incorporating Johnson’s insights and those of other worm harvesters.

The harvesters shared where harvests were consistently good, consistently bad, declined from good to bad, or were inconsistent from one year to the next. The students used this information to redesign their sampling protocol and mathematical model to test the worm harvesters’ proposed reasons for the declines. The students targeted the sampling to assess how mudflats with declining worms were different from mudflats with more stable populations.

Juvenile Declines

The data the students collected revealed important differences in worm populations in the different types of mudflats. The more stable sites had lots of “babies” (our term for worms shorter than 4 centimeters—about 1.6 inches—that aren’t larvae), juveniles, and adults. Strikingly, though, sites where marine worms were declining had very few juveniles. The lack of juveniles in certain mudflats suggested that some unknown factor was killing or inhibiting their growth or survival.

In 2023, a new student team began working to identify the reasons why juvenile worms were declining. This team is using a protocol developed by Maine’s Department of Marine Resources to compare patterns in Acadia’s worm populations to patterns in other populations across the state. Do declines in marine worms look similar across the state? Do the declining flats all lack juveniles? If so, a similar cause may be driving widespread declines, and perhaps similar management responses could help. But mudflats aren’t easy to read if you don’t have intimate knowledge of them, so harvesters will also help guide the 2023 student research team.

New Allies

Maintaining the health of mudflats relies on studies like these. In this case, working with marine worm harvesters is providing critical knowledge that we may not gain through conventional scientific approaches alone. And Acadia park managers now have new allies—harvesters—as they work to protect the health of the area’s coastal fisheries, so vital to the communities who work in them.

About the authors

Hannah Webber
Hannah Webber is the director of Marine Ecology at the Schoodic Institute at Acadia National Park. Image used by permission of Schoodic Institute.
Close-up of a smiling man in a gray fleece beanie.

Abe Miller-Rushing is the science coordinator for Acadia National Park. He oversees research in the park and works with the Schoodic Institute to help lead Acadia’s Research Learning Center. Image courtesy of Abe Miller- Rushing.

Acadia National Park

Last updated: March 13, 2024