Fish Attraction Devices – Floating and Submersible
LED Arrays
An LED Array is a visual Fish Attraction Device made up of
Superbright Green, Blue and full spectrum White LED's.
Fish eyes peak in the blue/green spectrum, these
wavelengths also penetrate deeper than other colors, cool
white full spectrum LED’s are included to make for better
human viewing of fish around the array. In a floating
array or underwater light 100% of the light is available
whereas an overhead light, depending upon ocean
conditions, may be attenuated up to 90% due to the light
reflecting off the surface. For photographic purposes the
difference between an overhead light and an underwater
light would be about two full aperture stops. In clear
off-shore water blue/green light may penetrate to 100
meters, cloudy inshore waters will limit penetration.
These pictures show first generation LED arrays, the LED
is shown with voltage turned down to prevent photo
wipeout. In actual use the LEDs are extremely bright, from
a fish viewpoint it is virtual cloud of light.
Illuminated FAD's are used by fisherman to "make bait" and
attract game fish, and by fishery scientists to attract
and identify species within a given area, in this instance
underwater cameras using, ambient, IR and/or full spectrum
lighting would be positioned around, below or over the
array recording fish species and activity, many new
species of fish and other aquatic marine species have been
discovered using these FAD's.
Fish are attracted to light in a roundabout way, it's all
about the ocean food chain wherein the big fishes eat the
little fishes and the little fishes eat the plankton that
are nourished by the sun. At the bottom of the food chain,
the starting point, are single-celled marine plants called
Phytoplankton (algae, primary diatoms, dinoflagellates,
coccolithophordis, etc., are collectively called
phytoplankton). Phytoplankton
float within the upper layers of the oceans, they use
solar energy from the Sun (photons) to convert
(photosynthesize) carbon dioxide and other nutrients
derived from ocean bottom upwelling's into carbohydrates
that in turn is the food used by marine creatures.
Zooplankton such as macro-shrimp, copepods, jellyfish,
etc. feed on Phytoplankton, smaller Zooplankton are eaten
by larger Zooplankton which in turn are eaten by bait fish
including small squid, anchovies, sardines, lantern fish,
etc...
Fish appear to be programmed to know that light may be a
potential food source thus at night they will be attracted
to a light source, this may be due to the fact that most
predators and game fish feed 24/7, at night an abundant
food source is the tiny but luminous lanternfish, thus any
night light may translate into a grouping of lanternfish.
Large predators and game fish will typically "stand-off"
from the brightly lit area foraging bellow and on the
periphery of the light zone picking off the bait fish as
they dart in and out of the bright illuminated feeding
area. Observing these larger fish is accomplished by
placing underwater or floating video cameras with
(invisible) infrared lighting on the periphery.
When fishing with
floating or underwater lights cast your line into the dark
surrounding waters and/or drop a line along side or close
by the array to about 8 to 10 feet below the array. A bit
of chum helps a lot.
During the spawning season California Market Squid
(Logilo) are particularly attracted to underwater lights
and floating light arrays offering easy harvesting.
These inshore
waters are usually cloudy obviously the more light the
better but even a small light can be very effective
depending upon the competition from lights in the
immediate area.
Although blue/green (aqua) is the preferred wavelength for
fish attraction that color, when viewed from a boat deck
the water appears dark to the human eye thus the fish that
are attracted are difficult to see. The present
generations of super bright (Cool White, not Warm White)
full spectrum LED’s contain a large spectrum of
purple-blue-green thus they not only attract fish but make
for easy human viewing. Nothing is accomplished by using
colored filters over a white light. Today full spectrum
cool white is the easiest way to go. To check the full
color spectrum of a white LED hold a CD disc near the LED,
the CD will reflect the full spectrum much like a prism.
The difference between a cool white and warm white will be
noticeable.
The following FAD describes a floating LED array with a
difference, it is essentially a poor man’s “Holographic 3D
projector", best results are obtained in water with poor
visibility as it utilizes particles in the ocean water as
a reflective "3D" projection screen.
In this instance the target fish species would be
Yellowtail or White Sea Bass usually off San Clemente
Island or the backside of Catalina Island where inshore
water conditions (visibility) are usually poor. White Sea
Bass forage in these murky waters using their lateral line
sensors to locate prey, usually market squid, and then
vision for the final pounce.
The array consists of 8 10mm large super bright cool white
LED's electronically wired as strobes, they are mounted in
a circular pattern in a 10" watertight container, the
jumbo 10 millimeter LED's protrude thru the bottom to take
advantage of emitted side-lighting and sea water cooling.
Not visible in the video clip, on the bottom in the center
of the container surrounded by the LED strobes, is a 3
inch long by 3 inch wide reflective cylinder, the strobes
flash in a consecutive counter-clockwise motion around the
cylinder which reflects the light flashes in a rotating
360 degree pattern. As the strobes flash around the center
cylinder the cylinder blocks the back side light, the
result is a flash on one side of the cylinder and a dark
shadow on the reverse side; this gives the appearance of a
dark object chasing the flash around the array.
A fish below viewing the display would see what
would appear to be an excited rotating "bait-ball" or
maybe a shoal of agitated spawning market squid, both
sought after food targets for most predator game fish.
The circuit draws less than one watt making it
practical to use self-contained batteries. Still working on an
underwater video.
An
excellent source for ready-made fishing lights at
reasonable prices:
http://www.fishinglightsetc.com/
We highly
recommend their 12 volt super bright LED submersible full
spectrum cool white lights.