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New Durham fish hatchery keeps region stocked

CONCRETE RACEWAYS with black nets hanging over help to protect the fish from predators. Weston Sager. (click for larger version)
July 28, 2010
NEW DURHAM — Next time you catch a salmon or trout in one of New Hampshire's lakes or rivers, you may want to send a thank-you note to the men at Powder Mill Fish Hatchery.

Set next to the serene Merrymeeting Lake in New Durham, the Powder Mill Fish Hatchery is easy to pass over; only a few white outbuildings and a small field of concrete beds comprise this seemingly modest operation. But looks can be deceiving: this hatchery is the largest supplier by pounds of trout and salmon to New Hampshire's lakes, rivers and fishing derbies, with a yearly output of just under 300,000 fish.

Operated by New Hampshire Fish and Game, and funded by fishing license fees and federal aid, this particular hatchery has been in operation since the 1940s. Now, Powder Mill offers self-guided and guided tours to visitors who wish to learn more about the hatchery's history and operations.

Salmon hatchery

Tucked in a corner next to the hatchery's garage is a small white building. This unassuming structure is the salmon hatchery.

"This is where it all begins," explains Jason Smith, the NH Fish and Game Hatchery Supervisor.

Entering the building, Smith points to the wall at a number of dresser-like stacks. These, he explains, are where the salmon eggs incubate during the fall and winter months.

Reaching down, he grabs one of the trays and pulls it out.

"Each tray holds about 5,000 salmon eggs," he says. "The trays are stacked seven tall, so each one of these stacks holds about 35,000 eggs."

Around 80 percent of the eggs hatch into fish, and the unhatched eggs are discarded, according to Smith. The unhatched eggs are susceptible to mold, which can threaten the well-being of nearby eggs, one of the many considerations that keep the Powder Mill crew continually busy.

After hatching, the miniscule fish are transferred to the half-dozen large metal tanks located in the center of the room. These tanks, along with every other fish tank at Powder Mill, are gravity-fed by the nearby Merrymeeting Lake, no pumps necessary.

"It's a flow-through system," Smith explains. "We don't re-circulate any of the water here."

The fledgling salmon are fed vegetable meal with added vitamins and minerals, which is not unlike the fish food found in a typical pet store. After the salmon have grown to 2-3 inches, they are moved outside to the so-called "raceways," or long, slender concrete fish tanks that house most of Powder Mill's aquatic residents.

"This hatchery is where all the landlocked salmon in the state come from originally," says Smith. "The lakes and streams don't provide a suitable spawning habitat for the salmon."

And as for the name 'landlocked Atlantic salmon.'

"These salmon are a cousin of the Atlantic salmon we all know," he explains. "They are called 'landlocked' because they don't leave the freshwater lakes and streams to return to the ocean."

But there is some debate about whether these salmon are native to New Hampshire.

"It depends on who you talk to," says Powder Mill superintendent Tom Givetz.

But several species of fish grown at the hatchery are undeniably foreign. The rainbow trout are from California and the brown trout come all the way from Germany. Only the brook trout is a native of New Hampshire.

But not to worry, these fish are not an environmental concern. They are non-invasive and cannot survive without the help of fish hatcheries like Powder Mill.

The "raceways"

Outside the hatchery lie a number of concrete fish tanks, dubbed "raceways" by the crew. These are the heart of the hatchery and house the majority of the facility's fish. Each tank typically holds between 6,000 and 20,000 fish, but they are capable of even greater capacity, according to Givetz.

"One of these raceways can hold 120,000 fish depending on their size and the water temperature," he says.

Similar to the tanks inside the hatchery, the raceways are gravity-fed a continuous supply of fresh water. Still, the crew at Powder Mill has to keep tabs on the raceways' cleanliness.

"We have to vacuum the fish waste out from time-to-time," says Smith. "But it makes great fertilizer."

He then points to a strange-looking machine at the top of a small hill whose shining metal exterior contrasts sharply with the old wooden buildings that surround it.

"That's the UV machine," he says. "It uses ultraviolet light to disinfect the incoming water to protect the fish from disease."

Smith is grateful for the machine because it helps protect against one of the biggest dangers.

"Disease and problems with the water supply do the worst damage," he says.

But these are not the only threats to the fish. Draped over each grouping of raceways are large black nets that help to discourage predators, such as herons or eagles.

"Before these nets, predators would eat some 40 to 60 percent of the fish," says Smith.

Working at the hatchery

Smith and Givetz halt in front of the rest of crew who are busy with work. They say they are conducting "sample counts" to determine fish weight and growth rate.

"Sample counts are the basis of everything," Smith says.

After determining the fish were of an appropriate weight using a bucket and scale, the Powder Mill crew then begins a process called "thinning." First, the crew dips their nets into a tank, then weighs the nets that are full of wriggling fish and finally dumps the nets' contents into an adjacent tank, all with remarkable efficiency.

According to Givetz, this is one of the many daily responsibilities of the crew, who take great pride in their jobs as the caretakers of this facility.

The show pools

The journey progresses from the concrete raceways to a natural-looking "show pool" located on the forest's edge. This small pond contains fish much larger than the six-inch-and-under fish that occupy the raceways.

"We keep this here for visitors," says Givetz. "This is where the big fish are."

However, the hatchery does not keep most of their fish for long enough for them to reach these massive proportions. They stock the lakes and rivers with fish much smaller, usually in the 10-12 inch range.

The main show pool does not end the tour, however. A thin stream running beside a nature path leads to the lower portion of the hatchery, where there are even more ponds and pools teeming with fish. Those bodies of water holding smaller fish are draped in the black netting, but the four larger ponds in the center of the area are free of this protection. These are additional show pools stocked with more full-sized salmon and trout.

In the midst of Givetz's explanation for the lower portion of the hatchery, Smith excitedly points to a tree.

"That's a bald eagle!" he exclaims.

Sure enough, a bald eagle, with trademark white head, is perched in a nearby pine.

"He lives in the area," says Givetz. "He sometimes feeds on the fish in the show pools."

Certainly a loss for the fish, but it serves as yet another fascinating sight for the hatchery's visitors.

Although the hatchery is in the process of upgrading its self-tour, Givetz urges people to visit anyway.

"Visitors are always welcome," he says. "And we encourage questions."

The Powder Mill Fish Hatchery is located at 288 Merrymeeting Lake Road. Visitors can tour the facility from 8 a.m. to 4 p.m., seven days a week. Guided tours are available by prior arrangement. Call the hatchery at 859-2041 for more information.

Weston Sager can be reached at 569-3126 or wsager@salmonpress.com

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