I Stopped a Fish Kill Today.
By ERIC P. ORFF, wildlife biologist
110 River Rd., Epsom, NH 03234
Tuesday, October 16, 2001, 08:45 AM- Suncook, NH
I arrived at the lower dam on the Suncook River this Tuesday morning to
check on the downstream migration of literally millions of river herring
or alewives. There has been an ongoing effort for nearly a decade
to restore alewives to the Merrimack River, and the Suncook River has played
a pivotal role in this restoration effort.
Historically alewives swam up the Merrimack River and its major tributaries
by the untold millions each spring to spawn in the quiet waters of the lakes
forming its headwaters. The adult alewives after living in the sea for two
to three years, and growing to ten to twelve inches long, make a made dash
up the rivers to lay as many as 200,000 eggs per female.
Native Americans caught multitudes of alewives with nets all along the Merrimack
River system. They also constructed special fish traps, called weirs, that
were set along the rivers. Weirs Beach on Lake Winnipesaukee retains in
name only the significance of a time lost. The runs of alewives were lost
as well beginning with the construction of dams along the tributaries.
On the Suncook River, in what was to become Allenstown and Pembroke, and
locally known as Suncook, the first dam was constructed in the early 1700s.
The waterpower served a local grist and sawmill. In 1848, a huge dam was
constructed across the Merrimack River in Lawrence Massachusetts seemingly
forever altering the upstream migration of fish. Within two or three years
the tremendous annual migration of Atlantic salmon, American Shad and alewives
were lost.
However all was not lost, for efforts have been underway for over three
decades to restore shad and salmon to the Merrimack. Although the salmon
restoration has been met with limited success, the shad restoration has
been very successful. Over 76,000 shad were passed over the fish passage
facility at the dam in Lawrence in the spring of 2001.
Alewife restoration efforts had taken a back seat to the more noteworthy
game species, salmon and shad. A restoration effort was finally begun in
1994. New Hampshire Fish and Game fisheries ecologist, Bill Ingham initiated
the effort by transporting 200 adult alewives from the Cocheco River in
Dover to Northwood Lake in Northwood.
According to my diary the fish were released about 2:00 PM. on April 24th
1994 as I accompanied Bill. I have had a life long interest in the Merrimack
River since I grew up in Londonderry and often fished the local brooks for
trout until they entered what was then the open sewer of the Merrimack.
I have lived on a bluff overlooking the Suncook River in Epsom since 1979
and have taken a keen interest in it as well.
Although alewives are not considered a game fish, they provide a tremendous
forage base for nearly all the other larger fish. From the lakes where they
are spawned and grow down through the river system as they migrate, and
especially out in the sea, alewives are providing nourishment to others.
Each year some of the most productive fishing for striped bass occurs in
the lower Merrimack as these giants follow the migrating alewives into the
river. I watched three river otters indulge themselves in a school of juvenile
alewives above the Northwood Lake dam on October 2nd. The return of alewives
would help bring the entire system back into balance.
Since 1996, the U.S. Fish and Wildlife Service fisheries staff have stepped
up the transfer of fish from the coast, stocking several thousand adult
alewives in to the two major tributaries of the Suncook River, Northwood
Lake and Suncook Lake in Barnstead. Thanks to this effort, several million
eggs hatch each spring in these lakes and by September millions of juvenile
alewives are nervously awaiting their trip down the river and out to sea.
The hordes of fish (huge schools often can be seen by late September at
the dams) are released to migrate down stream when the dam boards are removed
each fall to lower the lake levels for the winter.
The dam boards were lowered at Northwood Lake on October 6th. Because of
the huge numbers of fish that have raced out of the lake in past years when
the dam boards were pulled, this year the public was invited to watch. A
newly formed conservation group The Friends of the Suncook River hosted
the "Million Minnow March" that rainy Saturday in anticipation
of the spectacle. About 70 people crowded around the dam to stare at the
torrent of water leaving the lake once the boards were removed. But fish
being fish, they swam their merry way and elected not to join the festival.
Residents, who lived on the lake, and came to watch, have marveled all summer
long at the huge schools of minnows swarming along the shore.
The migration began four days later on October 10th. By Thursday, the 11th,
a few speedy alewives were well down the river and were passing the two
hydro stations on the lower Suncook at Pembroke hydro and the China Mill
hydro station. Because of the low flows in the river these plants had not
been operating. It is the lowering of the lakes above which sends a torrent
of water and juvenile alewives down river that also enables the hydro stations
to begin to generate electric power; sometimes a deadly combination.
By Friday afternoon the migration was well underway. I enjoyed an unusually
warm mid October evening on the banks of the Suncook at a cookout at a neighbors
picnic spot at the river's edge. As far as I could see up and down the river,
for over a hundred yards in either direction, the characteristic dimpling
of the surface by juvenile alewives could be seen. We all marveled at the
sight for the remaining hour or two before dark. Even then, when I took
a strong flashlight and cast its beam on to the river I witnessed the stampede
continue into the night.
The next afternoon I stopped by the China Mill dam to watch the fish tumble
over a bypass gate near the intake of the hydro station. The turbines remained
still and hundreds upon hundreds of little silver streaks were swept over
the spillway and were quickly carried down and deposited not 100 yards from
the Merrimack River. I watched the race downstream for nearly an hour. At
one point I counted about 300 fish a minute going over the falls. Most of
the water was still spilling over the main dam so just a fraction of the
fish was sweeping by my eyes. It was still a marvelous sight to witness.
After all 2,000 adult alewives were placed in Northwood Lake on May 5th.
Potentially 5,000,000 to 10,000,000 (million) juvenile alewives were descending
the river as I watched!
This brings me back to Tuesday morning, October 16th, 08:45 am: As I approached
the hydro station I could see that the operators were now generating electricity
as the current was rushing into the power canal that delivers the water
to the huge intakes to the turbines, now whirling away. But my heart sank
as I noticed that the bypass was not opened AND right in front of the intake
grill two large schools of juvenile alewives were swarming. I quickly made
my way around the canal and a second glance at the water showed it devoid
of fish. They had been swept into the intake's powerful grasp.
I quickly made my way around the back of the huge brick factory that has
stood here for over 150 years drawing its strength for the river itself.
It is no easy task to get to the discharge end of the hydro station. You
must fight through a jungle of growth, slip through and under a portion
of the fence where the river has eaten its foundation, and then traverse
the narrow corridor separating the factory and the river. Even this stretch
is a challenge. I fought my way along the banking and sprinted past the
two pipes three stories over my head spewing steam and fabric debris out
their snouts like angry dragons. It was obvious that sometimes a great volume
of scalding steam and debris is discharge on to the path I had selected.
At the tailrace of the hydro I saw what I expected to seefish dying by the
hundreds. Some fluttered a fruitless and vain attempt to swim with their
torn bodies in the swift current. The bottom of the discharge canal was
littered with the silver glimmering bodies of those that had succumbed to
the turbines minutes before. Most fluttered by in a steady stream holding
on to their last minutes of life. Some were just bits and pieces being swept
along and tumbling in the current at the bottom of the canal. I saw no survivors.
His was the same bleak image that I had seen before in fact, in 1996. That
year, while on the opposite side of the Merrimack River from where the Suncook
River enters, I noticed a huge swarm of gulls diving and feeding. I drove
over for a closer look and discovered a massive fish kill. Perhaps millions,
as the whole bottom of the Suncook River and well out in to the Merrimack
were littered with dead alewives. There were no gulls here so very likely
this fish kill had just started. There was far less death this time, but
clearly thousands of once vibrant little silver-sided baby alewives were
strewn down the river in a scene of mass carnage
I quickly made my way back around the old mill building and was fortunate
to meet the hydro operator as I arrived back at the intake. "You're
chopping up the fish" I exclaimed. He quickly shouted to another fellow
to run it and shut it down. At 9:02 the intake pipe belched back its last
gasp of leaves and young fish. The fish kill was over!
The hydro operators at this site and the one up river have agreed to bypass
as many fish as possible. Usually water is allowed to go past the intakes
and many of the fish can continue downstream unharmed. This operator said
that he had been watching for fish and regularly checking the canal. However
a school of fish did manage to slide down to the intake unnoticed. Both
this and the next upstream hydro facility, the Pembroke Hydro Station are
under new ownership and they feel very strongly that all the fish should
be allowed downstream unharmed. Fish and Wildlife Service biologists have
been working with them to minimize fish losses by recommending flow bypasses
and other diversion plans. The hydro operators have greatly reduced their
generator capacity by slowing down the turbines so the fish are not sucked
into the intakes and then the fish can be directed over the dams by allowing
a significant amount of water to bypass the intake and carry the fish away.
Progress is being made but there is much that remains to be done to restore
the Suncook and Merrimack Rivers.The Friends of The Suncook River hope to
be a part of a solution to fish losses that are plaguing the restoration
efforts of alewives to the Merrimack River system. They can be contacted
at suncook@worldpath.net
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