Dark Walleyes in Lake Nokomis?
April 1, 2007
from the Wenonah neighborhood, asks: “I
was running around Lake Nokomis one night when
I saw patches of luminous
water east of the Cedar Ave bridge. And, in that patch
were what I can only describe as glowing eyes
watching me. An old timer fishing off the observation
platform tried to convince me that Nokomis
walleyes glow in the dark, especially
during a full moon. I almost hate to ask, but
was he pulling my leg?”
was a new one to us. But NENA researchers hit the
archives and discovered much. Technically, the Lake
Nokomis walleyes don't light up by
themselves. But, then again, they do glow
in the dark. Read on...
In 1887, a German button maker, John Frederick Boepple,
arrived in the Mississippi River town of Muscatine,
Iowa. There he opened a mother-of-pearl button factory
supplied by the abundance of American pearl mussels
from nearby rivers and streams. Business boomed, but
the work was difficult. To make it easier for his freshwater
divers to find the mussels in the murky water, Boepple
introduced a small effofluorescent freshwater
shrimp into his backwater mussel "farms." This
schooling shrimp, Neocaridina denticulata fluorisis, "Glowlight," has
the unique ability to emit a bluish-white light when
agitated or mating. It was a brilliant move. Freshwater
pearl divers would simply sweep their hands in circles
near the bottom to light up the shrimp and help illuminate the mussel beds.
Add a Dose of Fear and Panic:
ahead to February 1942: Dozens of amazed people witnessed
the crew of a small German submarine, U-235, frantically
running fore and aft trying to “rock” the
sub off a mud bar in the Mississippi River north of
Baton Rouge. The U-boat escaped, but the incident
set off a wave of panic during the opening
months of World War II. The War Department,
fearing deep penetration into our coastal waterways,
ordered the US Coast Guard to develop a plan to discover
and capture this menace.
in a Ford:
At the same time, the US Navy was developing their
own 2-person submarine. Ford
Motor Company was building the B-1 Class subs at its
St. Paul Highland Plant along the river’s edge.
The first example, nicknamed the "Twofer," was nearly
finished and a launch was planned for May. However,
the Mississippi exceeded
flood stage that month. Leery of the treacherous currents,
the first test unit, T1, was trucked across the river,
closest “still” body
of water, Lake Nokomis, for its "seaworthiness" test
in June, 1942.
You Get Four Eyes:
weeks, drab green tanker trucks secretly released millions
of the Glowlight shrimp into the lake. From the air,
the trainees could easily spot the shadow where a submersible
would displace the agitated shrimp, no matter how dark
the night. Problem solved.
On July 4, the
Coast Guard and the Marine Air Reserve commenced Operation
Four Eyes, a classified mission where a series
of manned barrage balloons were positioned at intervals
along the Mississippi River. Training for observers
and crews was held at Lake Nokomis, chosen because
of its proximity to the Marine's Air Reserve squadron
at Wold-Chamberlain Field and of course, the available
Twofer. It soon became apparent that night observation
was nearly impossible, so the Coast Guard tried several
methods to highlight renegade submersibles -- such
as flotillas of floating oil lamps or submarine nets
attached to bell buoys. All provided impractical at
best. It was then that a young Marine reservist named
Boepple from Muscatine stepped forward with an idea.
Quiet On the Northern Front:
war ended and the military left, but the freshwater
shrimp stayed. They did well, multiplying rapidly because
of the nutrients in the lake, especially the phosphates,
a mineral that the shrimp use to produce their fluorescing
pigments. Area seniors might remember when returning
GI’s would take their sweethearts to Lake Nokomis’ northern
hillside at night and enjoy the view, marveling at
the mysterious bluish light in the water.
Beginning in the late 70's, the State
DNR stocked Lake
Nokomis with thousands of walleye fingerlings.
The fish quickly developed a taste for the glowing
shrimp, an easy catch for the famous night
predator. The walleye (Sander vitreus vitreushas)
has relatively large eyes that, like a cat's, reflect
light. This is the result of a specialized light-gathering
layer in the eyes called the tapetum lucidum which
allows the fish to see well in low-light conditions.
This has the effect of concentrating and reflecting
the shrimp light--and moonlight--back towards the viewer.
During a full moon, the shrimp will congregate near
the surface in a glowing mating ritual which attracts
the walleyes and other game fish. But, only the walleye's
large eye's reflect the additional light, making them
easy to see.
interesting side effect is that newly hatched shrimp,
unable to swim for themselves, attach themselves
to the scales and soft tissues of a host fish and
ride around the lake feeding on tiny particles that
pass by. The juvenile shrimp are highly reflective
at that age, but normally unfluoresced while passively
cruising around. However, a fish with enough of the
hitch-hikers will appear to glow when struggling
against a fishing line or removed from the water.
The effect can last for several minutes to a half
hour or longer.
Ford went on to produce 13 of the inland submarines
at their wartime foundry just below the lock and dam.
That site is now a truck parking lot, visible half way down the
river bank. The assembly and dry dock area to the south
was cleared and returned to the City of St. Paul for
Hidden Falls Park. All that remains are chunks of broken
concrete and the boat launch, now a public ramp.
The T1 "Twofer" kept patrolling the lake until
it capsized and sank during a gale in November 1944.
of the two balloons assigned to Nokomis met a somewhat
slower demise when an overzealous 10 year-old "soldier" shot
a hole in it with his trusty Red Ryder BB gun.
After the war, pollution and the switch to zippers and
plastic buttons sealed the fate of Muscatine's mother-of-pearl
and cultured pearl industry. Today, only one company remains.
remaining barage balloons were scrapped,
and much of the lightweight fabric was sold to
an obscure Hollywood garment manufacturer. They turned the rubberized silk
into a highly successful line of specialized undergarments.
That company later became Frederick's.
1950, the Park Board erected a modest limestone and
bronze monument honoring the wartime effort on the
south end of the lake. Ironically, in 1969, a Marine pilot, freshly returned
from Vietnam, careened off the Parkway and launched
both his new Pontiac and the monument into the lake.
The car was fished out; the monument wasn't.
the walleye have greatly reduced the shrimp population
in recent years, there remains several communities
at the southern and northwestern edges of the lake.
resemblance in the above story to actual fact may
be coincidental and could be disregarded, depending
on your mood. April Fools!
from the Bottom Up and other stories
that you may not have seen yet.
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