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If there has been any real revolution in fishing over the last 20
years, it's been "structure fishing". Bass fishing as a
sport, depended on shallow water "bank beating" since
it's inception. Over the last 20 years, it has become fashionable
to wander off shore in search of more and bigger fish. Much has
been written and discussed, but there still seems to be some
confusion over structure fishing, even among the pros, and the
majority of the fishermen have just become off shore fishermen,
not structure fishermen. Let's look at what we mean by structure
fishing, and some of the tricks of the trade.
The definition of structure is a change in bottom contour,
(i.e. depth), which results in an irregular feature on the bottom
of the lake. Now just about any quick change in depth results in
some type of structure, a hump, point, ledge, or something. The
biggest misunderstanding seems to be the definition of
"quick". Quick is a relative term. In a traditional
reservoir, this could be anything from a vertical drop to a
gentle slope dropping 5 feet over a 30 yard distance. In a
natural Florida lake, where it may normally take 1/4 mile to
change depth by 1 foot, it may be a 6" deep channel running
through a 5 foot deep flat, or a two foot drop over 30 yards.
Where ever you find it, structure is another edge in the
underwater world, and we all agree that fish just love edges.
Let's spend just a minute talking about what structure isn't.
Structure isn't a weed bed on a flat, or an isolated stump, or a
brush pile. All of these things are "cover". A weed bed
may constitute a different type of edge, both of the weeds and of
the bottom composition, but not structure. Wood, whether natural
or man made, is just somplace to hide. Likewise, a feeding flat
is a place, not a structure. We all have seen times when fish are
on the flats and relating to cover. Even during those times,
there will still be some fish around the surrounding structure.
Even on days when the fish are straying away from structure, they
generally won't go that far if they don't have to. Learn to
recognize structure and it can narrow your search for fish
dramatically.
Now that we can agree on what is structure and what is cover,
we can also agree there are times when one or the other seems
most important. Deep structure without cover can and does
normally hold a few fish, but generally not a great
concentration, at least of bass, (catfish and crappie are another
story). And we blow by miles of shoreline or shallow water cover
every trip that doesn't have a concentration of bass. But put the
two together, and you generally will find the fish stacked at
least some of the time. The trick then is to know the other
variables and be there at the right time. And every once in a
great while we can find that honey hole with both structure and
cover that have fish all the time, at least until we fish it out
and have to find another one.
Types of Structure
We can define structure types by the relationship to the
surrounding depths. The basic component of structure is the
ledge. A ledge is simply a distinct change in depth. In a
southern resevoir, this might be a drop of 5 feet over a twenty
foot slope. In Florida, it is most times a drop of 6 inches to 1
foot over the same twenty foot slope. A ledge, by our definition,
is a fairly straight line of depth change. Start putting some
noticable curves along the lip of a ledge, and you get other
structure. A point is a protrusion of shallower water along a
ledge. Surrounded by deeper water on three sides, it is the most
recognizable and often the most productive type of structure. The
opposite of a ledge is a cut. A cut is an indention in the line
of a ledge with deeper water surrounded by shallow water on 3
sides. A hump is nothing more than a ledge that wraps around on
itself, or an underwater island of sorts. A hump has deeper water
on all sides. The opposite of a hump is simply a hole, literally
deep water with shallow water on all sides. There are several
other types we can talk about, but these are the basic types.
We now have our basic definitions, but we need to put some
size restrictions on them, else everything is some type of
structure. For instance, the main lake body could be seen as a
hole, or simply a round set of ledges. We need to decide which
one because we'd like to fish the structure differently depending
on which type of structure we call it. As a reasonable guide,
let's look for just a second on how fish use structure.
Structure, what ever it's form, is a type of underwater
transportation system. Fish generally follow a narrow depth
getting from one place to another. The advantage of using
structure edges is the deeper water provides an immeadiate excape
route if you happen onto something much bigger than you. Now just
like any road, fish rarely live right in the center lane. More
likely, they will be just off one side or the other, which is
were the cover part comes in. In any event, for our purposes, the
extent or limit of a useful definition for a structure is the
depth change itself and the reasonable area adjacent to the drop
where fish will wander off to feed. In the case of our hole, a
fish might reasonably wander out, say 100 feet into the hole
without loosing the advantage of the edge for chasing shad. So,
if we assume both sides of hole are good for 100 feet, then
anything that is over 200 feet wide, at it's narrowest part,
isn't a hole, just two separate ledges. Simularly, if a hole is
too small to make use of each side, you have a ditch or a
depression, not a hole. Each of these other cases may be useful,
but for our discussion, they aren't holes. Apply all of the same
comments to the other structures: points, humps, cuts, etc.
Cover and Structures
Even with our size restrictions, we still have a tremindous
area to work. But we can narrow the odds by putting one
additional restricution on our prime structure. We already said
we'd like structure with cover, but let's now say we want the
cover to end along the edge of our structure. A point with a
grass bed is good. But if the grass bed happens to end right at
the edge of the point, then the point is great!
Weed beds in particular are excellent types of cover to either
change types, or stop all together right at the lip of the
structure. A ledge may have heavy grass in say 10 feet on the top
edge, while have either a different type of grass or, even
better, no grass at all at the bottom edge. If you work the
outside of the weed bed, you actually are working three edges at
the same time, the vertical edge of the grass, the edge of the
weed bed, and the depth change of the structure. Add a small
point or cut in the straight ledge, and you have 4 or 5 edges.
This is the kind of high percentage spot worth spending hours to
find.
Standing wood is another case of cover at a structure. When
you are fishing an old road bed or creek channel and the wood
suddenly stops at a particular depth, you get all the advantages
of the structure and the cover. I have found it necessary to be
careful with defining wood on a ledge. Where you have creeks or
roads, you a likely to also have hills or mounds. In this case
you need to find a structure on a structure. Just because to the
bed runs at a consistant depth, the top edge will, more often
than not, rise and fall over mounds or small hills. A gentle
slope up an underwater hill may consentrate the fish at a single
tree because the depth is 6 inches different than the surrounding
trees. If you don't know what depth, it can be frustrating. On
the other hand, a slight mount in on one side of a bed can act as
a magnet for every fish in the area not actively hunting. Find an
area with several of these mounds and you've got your honey hole.
Depending on the local botany before it was flooded, you may be
able to spot these mounds by looking for a specific type of tree
which grew only on a mound or down in a cut. A perfect example is
willow trees that would tend to have grown lower and closer to
the water level of an old creek than say the surrounding oak
trees. Cypress trees are another sure tip off of a change in
structure level. You'll read many times about a tournament won
fishing a specific type of tree. More than likely, it wasn't the
wood type that made the difference, it was depth that type of
tree was growing in before the lake was built.
Water Temperature and Structure
We've now established looking for a structure with cover, it's
time to chose amoung all structures with cover that ends at the
structure edge. This will depend on several variables, water
clarity, weather, season, statification, temperature, etc. We
could try to consider everything, but for starters, there is an
easier way. Most of the changes can be interpreted as water
temperature. Like any other generalization, it doesn't work all
of the time, but for 80 - 90% of the cases, it works just fine.
The general rule of thumb: "The Colder the Water, The
Steeper the Drop." Pretty simple, and it works. During
winter and early spring, look for the fish to relate to a steep
drop into deep water. This might be from 5' or from 20' into a
deep hole, but the fast drop is the key. The fish will move
during warmer periods to the upper shelf to feed and may suspend
over the hole during those blue bird cold fronts. During summer
and well into fall, look for a gentle slope into deeper water.
The fish may range a couple of hundred yards from the structure
but at least some will be on slope for most of the year. The only
tough part about this is they may actually move deeper to feed
and return to the slope to rest. But again, for the most part
they will move into the cover for feeding while the bait is on
the bottom.
Everything else being equal, we still don't know at what depth
we should look for our structure. In the Florida Chain Lakes,
with different water clarity in different lakes, you can still
find structure, with cover, the correct type of slope, and the
correct contour in just about any depth. The tie breaker is again
water temperature, just not surface temperture anymore. The most
productive structure, all things being equal, will be where the
structure tops out at the same depth as the thermocline. A
thermocline, for those not normally worrying about those things,
is a physical layer between two different temperatures of water.
This normally exists when the lake is "stratified", or
during the summer when there is little movement between the upper
and lower water layers. In this case, the cooler water will
remain below the warmer upper layers. In the fall, as the upper
water cools, it will normally fall within the water column,
causing a lake to "turn over", normally tough days to
be fishing. Anyway, a structure near the thermocline with
appropritate cover, can be a gold mine for fishing.
There are several ways to find a thermocline if one exists.
The most obvious, and the most trouble, is to lower a temperature
probe and look for a dramatic, (3 - 6 degrees), change in
temperature. An easier way is to use your depth finder. A
thermocline will reflect sound waves if the temperature change is
great enough. Move to deep water and place your unit in manual
mode. Increase the gain, (sensitivity), until you see a solid or
broken line in the middle of the water column. If your depth
finder has the little fish symbols on it, this may take the form
of a line of fish around a particular depth. As you move the
boat, this line may move slightly up or down, (a foot or so), but
should remain pretty close for a given area. Find structure at
that depth, and you should find fish. By the way, during the dog
days of summer, you may find 2 or 3 thermoclines at the same
time. Generally, the fish won't be below the lower one, (commonly
about 25' in Florida). If you have 3 or more thermoclines, (more
common on reserviors where water 50' plus is the rule), fish the
middle one.
Fishing Structure
The absolute most important thing for fishing structure is
your depth finder. A depth finder which can mark in 1/10' or in
inches is ideal for this application. Also, you'll find it more
comfortable if your depth finder is mounted on the bow with the
transducer attatched to the foot of the trolling motor. If you
have only one depth finder, mounted on your console, then keep in
mind the depth being shown is for the stern of the boat, not
directly under you and your trolling motor. Get to be best
friends with your depth finder, for structure fishing, it's the
most important peice of gear you've got.
Most of the time, you'll find the majority of the fish on the
top lip of the structure. The rest of the time, you'll find the
fish suspended just past the lower edge at approximately the same
depth as the upper edge. Boat position is the key to effectively
fishing the structure. Run up and down your structure a time or
two and get to know the rate of the slope and where it bottoms
out at. Position the boat so at a full cast length, your lure is
about 10 over the top edge while holding the boat in deeper
water. Keep the boat at the same depth as you follow the contours
of the structure. If you find a narrow cut, back off and fish the
bottom of the cut as well as moving in and fishing the
surrounding lip. If you move over a point, make sure to go back
and fish the normal edge line across the top of the point as well
as following the point out into deeper water.
While you're fishing the top of the ledge, don't forget the
deeper side of the boat. Every 6 or 8 casts, turn around and
heave one out into open water. Make sure you monitor your bait on
the drop, that's were the bite will be for suspended fish. Pay
particular attention to suspended fish around the ends of points
and at the corner of flats.
After you've finished a run on a structure's top edge, if it
still looks promising, make another pass fishing the bottom edge.
Position the boat as close as you can to the top edge, (where
you've just fished), and use your bait to "feel" you
way along the bottom edge. If the cover stops on the top edge,
many times a different scattered grass, limbs, or simply trash
will pile up on the bottom edge. If you can't feel anything, and
when all else fails, you can count down your lure and get a
pretty consistant feel for the depth you're fishing. This is also
the pass you'd like to fish straight across points and cuts
looking for fish suspended in the middle. In general, this deep
water pass will also be your best bet of sticking that kicker
you're looking for.
If you think there are some suspended fish in the area, try a
long Carolina rig. Instead of simply pulling the bait along the
bottom, pop the bait up in the water. As the sinker drops, the
bait will actually whip upwards and you can effectively cover 6
or 8 feet off the bottom. In these situations, expect a very
light bite and give the bait plenty of time to float back to the
bottom before the next jerk. It won't be unusual to not feel
anything and simply have a fish on when you raise your rod. You
can increase your hook up ratio by gently raising the rod tip and
feeling for pressure before jerking the bait off the bottom. This
is a prime example of the wisdom of the adage, " The Jerk's
Free".
There are a hundred other ways to fish various structures, and
there are many more variations of the structures themselves.
We'll look in future articles at the more specific structures and
techniques, but this pretty much covers the basics. Give
structure fishing a try and I think you'll like the results. Like
most other techniques, it more a matter of confidence than
anything. Given the right situation, structure fishing can open
up a whole new world of schools of fish and big bites! See you
off shore.
Next: Structure Fishing 202 Click here to read it!
Paul Crawford
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