EDITOR’S NOTE: This is the first in a five-part series In a five-part Eagle-Tribune series on Merrimack River fish — the species, life cycles, and habits — along with the challenges they face and the wonder they evoke.
LAWRENCE — River herring are a resilient but diminished native fish with big eyes and forked tails for speed bursts, snappy direction changes and migrating long distances — all of which the fish deploy and depend on to survive in the Merrimack River.
Eluding predators and getting beyond the 36-foot-high and 941-foot-long Great Stone Dam by way of a chain-driven fish lift, called an elevator, pose steep hurdles for Merrimack River herring.
It wasn’t always so. In pre-industrial times, before dam construction, herring had a clean river’s entire width to migrate upstream.
Biologists say spring runs brought millions of the fish into the Merrimack, feeding indigenous people for thousands of years and later fertilizing crops for European settlers.
But these days, river herring are not getting past Lawrence in the numbers needed to sustain a viable population of migrating and spawning Merrimack River fish, says Ben Gahagan, a Massachusetts Division of Marine Fisheries biologist who leads its recreational fisheries program.
“We know they can not complete the life cycle, Gahagan says. “There is no way to get past (all) the dams.”
Lawrence’s towering granite block wall is the first upstream dam encountered by fish migrating from the ocean through the river’s mouth at Newburyport.
Any herring that succeeds in passing the Lawrence barrier, by way of the lift, faces additional barriers in Lowell’s dam and three more in New Hampshire.
Help to boost migration might arrive after the next two years through two Lawrence Hydro Project studies, each of which includes metrics — means of measuring effectiveness — proposed by the Massachusetts Division of Marine Fisheries, National Marine Fisheries Service and U.S. Fish and Wildlife Service, and approved in May by the Federal Energy Regulatory Commission.
The project’s federal license holder, the Essex Company, a subsidiary of Patriot Hydro, and parent company LS Power, is responsible for the hydro project’s upstream and downstream fish passage system, and for their operation (in consultation with fish agencies) and evaluating their effectiveness.
The project is monitored and licensed by FERC.
The upriver passage of river herring at Lawrence have been up and, mostly, down over recent decades.
Successful years have been assisted by a fish trucking operation conducted by a technical team composed of fishery agencies’ biologists, who transport fish that imprint on the Merrimack and return from the sea to the river to spawn.
One hydro project study will measure upstream fish passage over multiple stages at the Lawrence Hydro Project.
Fish, attracted by an opposing water flow, get upstream of Lawrence, by entering a large bucket-like compartment as it fills with water and then is lifted above and dumped into an impoundment area beyond the dam.
Getting to the elevator relies on fish navigating beyond the tailrace and through the gallery and an open gate.
Broken machinery, some of which is submerged in water, has left the lift system inoperable for extended periods over the past few years.
The second study will track tagged fish movement in real time. A telemetric system, which uses an acoustic signal, automatically transmits information about fish movement and predation by striped bass.
The studies, to be conducted by Patriot Hydro, and the results will be filed by 2026 with the company’s application for a 40-year license to operate its 16.8 megawatt plant.
Project turbines, which also pose a threat to migrating fish, generate enough electricity to power 7,000 homes.
On an afternoon in late May, some 50,000 river herring — comprised of two like species, alewife and blueback herring — massed before the Great Stone Dam and Lawrence hydro-electric plant.
Fisheries biologists have described the herrings’ plight over the last year at FERC license hearings tied to Patriot Hydro’s application to renew its federal license to operate its plant.
But to see tens of thousands of fish together, and waylaid, was extraordinary — and sad for anyone who roots for the underdog.
On this day, and others during the spring run of herring and shad, the south side of the Merrimack River boiled with the 8- to 12-inch fish, swishing their tails and circulating in each others’ slipstreams but not moving forward.
For good reason.
The river herring, called by nature from the sea to upriver spawning grounds north into New Hampshire, faced a gauntlet of predatory striped bass.
Stripers have learned to position themselves by the narrow entrance, a 10-foot passageway, to the wonky fish lift, according to state and federal biologists.
A year ago, a technical team of federal and Massachusetts and New Hampshire fisheries biologists and a member of the Merrimack River Watershed Council stood on a bump-out on the O’Leary Bridge in Lawrence to witness the predation.
They saw stripers snatching airborne river herring that ventured close to the entrance to the Patriot fish elevator, said Matthew Cranney, a design and river restoration specialist with the Watershed Council.
Gulls descended on herring that landed on riverbank rocks, said Cranney, who grew up in Andover along the Shawsheen River, a Merrimack tributary.
In 2023, the number of herring that made it past Lawrence to traditional upriver spawning grounds crashed: only 6,129 of them made it beyond the dam; that’s about 1.4% of the record 449,000 that passed in 2018.
This year, as of June 21, the end of the spring run, only 35,312 river herring had passed the Lawrence dam, according to MassWildlife.
These fish, which live up to 8 or 9 years, are an anadramous species; they spend parts of their lives in fresh and salt water — most of it in marine waters; and they reach maturity at 4 years, with a female capable of laying 300,000 or more eggs, according to state and federal fisheries research.
Herring are a key to the river’s health, bringing nutrients to it from the sea.
They are also a critical food source for commercial and recreational fish as well as whales, eagles and osprey, Cranney says.
Gahagan says if it weren’t for the annual stocking program, maintained by the state and federal river technical team, there would be no massing of fish below the dam at Lawrence.
The technical teams have trucked river herring from the Lawrence lift to upriver spawning grounds; as well as egg-laden fish from Northern New England rivers to Lake Winnisquam in New Hampshire.
The fish imprint into the Merrimack River watershed.
Typically hatchlings spend two to six months in fresh water and migrate to the ocean and coastal water for three to five years before returning, in maturity, to the Merrimack and knocking on the door at the Lawrence dam.
A percentage of the waylaid river herring may backtrack and spawn in waterways off the Merrimack or return to the coast, says Cranney.
Ultimately, removing river dams and other barriers are more effective ways to restore fish populations, stem erosion and improve water quality, says Rebecca Quinones, MassWildlife’s conservation science program manager for the Natural Heritage and Endangered Species Program.
Barring the Great Stone Dam’s removal, biologists and conservationists will comb the fish study results as they seek ways to improve the upstream passage of river herring.
As it stands, the effort is a long game of cumulative improvements.
Cranney and the biologists who proposed river study metrics look forward to studying the collected information and finding ways to get more fish upriver.
There are many different fish passage solutions, says Cranney.
Volitional fishways, such as rock ramps, create eddies that allow the fish places to rest on the way up and have the advantage of not relying on mechanical devices or staff to operate them.
In the meantime, the resilient river herring, whose numbers up and down the East Coast have declined over the years due to habitat loss and overfishing, will continue to try to populate the Merrimack.