What makes a fish go for your fly is a topic highlighted in an article by Dr. David
Ross, a senior scientist with Woods Hole Oceanographic Institution in Hyannis,
Massachusetts. In previous articles for Saltwater Fly Fisherman, Dr. Ross has
discussed the senses that are most important to fish: smell, hearing and vision.
In the April/May 1999 issue of Saltwater Fly Fisherman, Dr. Ross talks
about whether or not your fly is appealing. This is a really terrific article and one
worth reading. Here are some highlights.
Basically, the senses of taste and touch don't factor into a fish's initial attraction
to a fly. Rather, to react to your fly, a fish must smell, hear or see it. When you
hook up, a fish has made one of these three sensory responses.
Most fish, especially game fish have an excellent sense of smell; some fish species
detect scent a million times better than humans do. A fish's sense of smell can be
particularly useful when the water is dark or too turbid for its vision to be effective.
Some species of fish communicate via scents; some fish actually emit chemical odors
to attract members of the opposite sex for mating, or to indicate danger or food.
Anglers, particularly those, who fish offshore, often capitalize on a fish's excellent
sense of smell by putting out chum to entice feeding activity. Fly fishers also use this
technique by free drifting chum flies (flies that resemble pieces of bait) into the scent
trail, a technique that's effective for most offshore marine species. Some anglers even
go to the extent of putting fish oil on their flies. But this would disqualify anyone from
an IGFA world record. Actually the most effective substance is human saliva, which
is why some fisherman feel that spitting on their flies will improve their luck.
Fish are very sensitive to sound. How many times have you been in the flats when
someone in another boat slammed down a hatch? You can visually see fish life
exploding underwater (called blowouts) as fish react to the sound generated. Fish
detect sounds in one of two ways: using their inner ear, or using their lateral line.
Fish can register sounds on their lateral lines within a range of 20 to 30 feet (what
scientists call the near field). Noises within 5 feet or less are picked up with extreme
accuracy. Sometimes fish make vibrations by swimming and then use the sound
rebounding to their lateral lines to detect nearby object possibly even flies.
Fish not only detect near-field sounds with their inner ears, but also sounds coming
from far away (from the far field). Species that have an inner ear attached or close
to their swim bladders typically have very sensitive hearing, because the swim bladder
acts as a sound-amplifying organ.
Because fish are so sound sensitive, it makes sense that noise-making flies are often
effective. Some noisy flies contain rattles (Rattle Rouse), others cause a surface
disturbance (Ultra Hair Bug), and some are bulky and push water (Tabory Snake
Fly). Rattles and poppers may draw fish from far distances, while flies that push
water work better in the near field. Noise making patterns are probably less
effective in the surf zone. Keep in mind that fish are wary of any unfamiliar noise,
such as boats, wading, or a fly slapping the water.
Dr. Ross believes that vision is of less value to fish for their survival than smell or
hearing. However, it's not known what fish actually see. There is evidence that
some fish may see in a special range beyond what humans see, including seeing in
polarized light. Most offshore gamefish only have blue and green in their spectrum.
So distinguishing colors are less important. Some recent research by Australian
scientists indicates that Marlin may detect some colors when the fish hook up
closer to the surface.
One important factor to consider - are the fish hungry? Some fish will gorge
themselves and others will not eat at all. During full moon periods, fish will eat
at night and just lounge around during the day. You know how frustrating it
is try to fish after a full moon. Also tides and weather influence feeding. So fly
pattern, color, shape, and motion won't make much difference. Another factor
is how similar in size and shape is your fly to the baitfish being consumed. Some
anglers feel the size and shape of the fly is more important than color. I believe
bigger flies catch bigger fish. ~ Doug
Mastering the Cast next time!