July 2008 12 / OutdoorIllinois July 2008 OutdoorIllinois / 13
On the surface, the notion of fish
being able to smell underwater
just doesn’t make sense. From a
human perspective, detecting
aromas while submerged in
water is literally impossible. We
breathe air, not water. But what about
fish—those full-time water inhabitants
that breathe by absorbing oxygen
through water? And why do fish appear
“It has been demonstrated that fish
can detect certain smells down to just a
few molecules in the water,” Burr
added.
What does this mean for fishermen?
Department of Natural Resources
fish biologist Alan Brandenburg, manag-er
at Little Grassy Fish Hatchery in
Williamson County, said it’s helpful to
understand how different species of fish
utilize their sense of smell and taste.
Some species rely heavily on smell and
taste while others don’t. Some
species—such as European carp and
various catfish—rely heavily on those
interconnected senses while other
species—such as panfish and bass—
feed primarily through visual triggers.
“A lot of fish will grab and taste
something before deciding whether to
spit it out or swallow it,” Brandenburg
said. “But not always. Look at a plastic
lure. It doesn’t taste or smell like any-thing
a fish would ever want to eat, yet
fish strike artificial lures all of the time.
It’s a visual response thing.”
To demonstrate how some fish
ignore their sense of smell or taste,
Brandenburg once rigged a “lure” from
a piece of plastic he found in the trash.
The plastic cigar holder he found had
zero potential as live bait. Yet when
Brandenburg added a hook and
twitched it through the water, he
caught a fish.
Visual cues or triggers are both
learned and instinctive feeding behav-iors.
The splash of insects falling into a
pond is quickly associated with food.
Of course, as with the junk plastic lure,
the splash doesn’t always represent
actual food.
At Devil’s Kitchen Lake at Crab
Orchard National Wildlife Refuge,
stocked rainbow trout appear to gobble
anything that floats down into the
water, possibly a learned response from
previously being fed food pellets at a
hatchery. Retired DNR biologist Jared
Garver—an avid trout fisherman—
always investigates the stomach con-tents
of trout he cleans after fishing at
the exceptionally clean lake.
Garver’s curiosity about rainbow
trout feeding behavior led to an inter-esting
discovery.
“Throughout one season I found
three cigarette butts, two plastic
worms, four sticks, a piece of gum and
a plastic minnow in the stomachs of
trout,” Garver reports. “Devil’s Kitchen
is such a clean lake, it makes me think
the trout will eat any unusual object
they see floating in the water.
“It also makes me think trout aren’t
nearly as smart as fishermen think they
are,” he laughed.
So, how important is smell among
the various senses fish use before decid-ing
to bite? For some species, it matters
greatly. Therefore, the use of
“stinkbait” for catfish or flavored corn
pellets for carp is clearly a good choice
for anglers wanting to attract those
species that rely on smell and taste.
Even for species with good eyesight
(the “sight feeders”), an added bit of fla-vor
doesn’t seem to hurt.
During a major bass tournament on
Rend Lake several years ago, this writer
shared a boat with TV pro angler Hank
Parker as he squirted a bit of scent on a
plastic worm before casting into a likely
bass hangout. Action had been slow,
Parker pointed out, and a spritz of his
secret potion might improve the odds.
Within a few casts, Parker hooked
and boated a bass. Yet, after several
more minutes and many unproductive
casts, he abandoned the spray and
changed lures.
There also is the impossible-to-quan-tify
influences of random coincidence,
as well as the psychological boost of
adding flavor to a lure that causes
anglers to sharpen their focus and catch
more fish.
For anglers, simply knowing that fish
can and do smell clearly leads to a more
productive fishing experience. The ques-tion
remains:What smells attract fish?
Wouldn’t we all like to know?
From stinky baits to lure
sprays, fishermen for
ages have assumed
fish can smell. Is there
any supporting science?
Story by Joe McFarland
Photos by Adele Hodde
Can Fish Smell
Underwater?
Does adding a little flavor to artificial baits
(left) attract more fish? Catfish anglers
have long believed that strong flavors can
be detected by specialized sensory
“whiskers” (above).
Ever wonder why fish appear to have
nostrils? Since fish “breathe” through
their mouth and gills, what good are
those tiny holes in the snout?
Carp and trout anglers maintain that kernels
of corn are good bait—but flavored corn
soaked in everything from strawberry juice
to butterscotch works even better.
to have nostrils if they actually breathe
through gills?
Are those “nostrils” connected to
olfactory smelling senses?
The idea that fish can smell is a basic
assumption by many sportsmen. Fisher-men
everywhere dunk their lures in
secret potions and use rotted, even fer-mented,
concoctions to attract species
of catfish and carp, all under the assump-tion
fish can somehow smell the bait.
But can fish really smell?
“Yes, fish can smell,” proclaims
Brooks Burr, a fish biologist at Southern
Illinois University at Carbondale. Those
little nostrils we see on the snout of fish
do, indeed, connect to internal cham-bers
that are equipped with folds of
sensory tissue. Those receptors detect
everything from sex hormones to trace
amounts of blood in the water.
(Photo by Joe McFarland.)
(Photo by Joe McFarland.)
