Trout ‘spy’ at Penn State reveals surprises
UNIVERSITY PARK -
Fishermen get many surprises in
discussing trout with Robert A.
“Bob” Bachman of Penn State.
Bachman set a world record in
studying brown trout for three
fishing seasons from camouflaged
“blinds” on Spruce Creek in
Huntingdon County.
First, he noticed that wild brown
trout use a “sit and wait” feeding
strategy over 86 percent of the
time. Second, he observed that
over 95 percent of the wild brown
trout in Spruce Creek feed in sites
without overhead cover during
nearly all daylight hours. And
third, he noticed that wild brown
trout feed more than hatchery
reared trout and move around less
than hatchery trout in the same
stream.
Bachman studied over 100 wild
brown trout intensively from April
through November for three
consecutive years. He recorded
peak feeding rates of 200 to 300
times per hour frequently between
noon and 2 p.m. in bright sunlight
during July and August. The “sit
and wait” feeding strategy con
sists of choosing a place to in
tercept food drifting along the
stream where the trout can see
well and conserve energy at the
same time.
He is convinced that feeding site
quality is also the key to deter
mining the number of trout in a
stream and how fast they grow.
This discovery questions the
validity of the theory that
overhead cover decides the
number of trout in a stream.
He claims the speed of a trout’s
growth, and how big it gets,
depends on the difference between
the energy gained from food and
the energy spent in catching it. He
noticed that hatchery trout,
brought into the research site, used
up more energy than they gained
mostly due to wasted
movements. Thus, they didn’t
survive well in the wild.
Bachman carried out his studies
while associated with the
Cooperative Fish and Wildlife
Research Unit at Penn State. In so
doing, he completed requirements
for the doctor of philosophy degree
in ecology.
Location and composition of the
Spruce Creek wild trout are sur
prisingly stable, it was noted.
'lndividual trout return to the exact
same sites month after month,
year after year. Significant
migration occurs only during the
fall spawning season. Of 18 trout
observed late one summer, 15
returned to the same foraging sites
and home ranges the following
spring. The next year, 11 of 14 trout
returned from the previous fall.
“Behavior of fishermen disturbs
wild brown trout in their normal
midday feeding,” Bachman
stated, observing that “in the
evening you certainly can get
much closer to brown trout without
frightening them.”
Bachman found that overhead
cover is used mostly by fish when
danger threatens. At such tunes,
cover is important, he affirmed.
Trout will take cover when an
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angler makes a clumpsy approach,
when a woodchuck swims across
the stream, or a heron flies over.
But in 20 minutes, the trout
generally are back to their normal
routine.
From his intensive observations,
Bachman could predict, within a
quarter of an inch, where a trout’s
head would come to rest after the
fish had been feeding. Usually such
position would be next to, above, or
below a certain rock or submerged
object.
Bachman knew the trout in his
section of Spruce Creek so well
that each one had a number and
often a name such as “Old
Yellowfin” and “Beethoven.”
From photographs he could tell
how much each trout had grown
from year to year.
He watched each fish for 15
minute intervals, punching into a
computer called the “Trout
Tracker” everything about a
particular fish such as fighting,
feeding behavior, position
changes, and hiding. Each time a
trout ate an insect, the time of day
and location were recorded. The
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observations continued for 10 to 12
straight hours daily.
“Rigid terrotoriality in the
traditional sense was not evident
among the wild i brown trout in
Spruce Creek,” Bachman
stated.'Tnstead, we found that the
Spring can he tough
on calves housed indoors
UNIVERSITY PARK - The
warm days and cold nights of
spring can be tough on youngstock
housed in poorly ventilated
quarters. Pens and stalls with
manure packs in them can become
pretty rank on warm spring days.
It doesn’t take much increase in
temperature to encourage rapid
release of ammonia and other
gases. It’s amazing how foul the
air in the old horse barn or chicken
coop can get on a spring day when
it’s full of calves and a manure
pack.
Many barns that 1 ad adequate
air exchange during :old weather
Todays profit minded poultry, swine, and grain
producers must think in terms of an automatic
system.
"System thinking" can help you (dan away problems
before you begin, or ft can help you automate away ’
problems you now have.
Hershey Equipment Co. is geared to provide ail
components of the system including equipment,
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tish share their tune in feeding
sites. There is, however, a
hierarchy of dominance. If three
fish use the same site, the largest
one dominates, but all three share
the area. And there goes another
myth about trout behavior,” he
added.
to control moisture become foul
during warm spring days. Shelters
with poorly placed openings may
need to have extra door’s and
windows opened on warm sunny
days and then closed some on
frosty nights to prevent drafts at
animal level.
Individual calf pens with four
solid sides can become par
ticularly offensive on warm muggy
days. More regular cleaning and
bedding may be necessary.
A little extra time and care to be
sure calves have good fresh air to
breathe this spring will pay
dividends in better health and
growth
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