Structure Fishing 101

written by Tim Allard

Structures are a big factor in fish habitat and certain types will concentrate fish.

Structures are areas where there is a variance in the depth or contours of the lake bottom.

If you’re new to fishing, knowing how to find structure and understanding how fish relate to it will dramatically improve your ability to find and catch fish. As a term, structure gets used a lot in fishing articles, television shows and presentations by professional anglers. In this guide I’ll define structure, discuss various types and share some tips for fishing them.

What is structure?

Structures are the physical features of a lake or a river bottom. From a fishing perspective, structures are areas where there is a variance in the depth or the contours of the bottom, and these changes can range from subtle to dramatic. Structures can be natural as well as human-made features of the underwater landscape. Structures are a big factor in fish habitat and certain types will concentrate fish.

Before I get any further, let me explain what structure is not. Sometimes cover is incorrectly used interchangeably with structure. Cover refers to objects in or on the water that provide shelter for fish, such as vegetation or a dock. Of course, finding structure and cover together can make great fishing spots (e.g., a hump with a dense weed bed), so it’s no surprise that the two terms get used interchangeably.

Some Basic Structures

Here are some common fishing-structures. A ledge is the beginning of a distinct change in depth. It marks the top of a drop, which is simply the sloping of the bottom towards deeper water. Ledges and drops are main structures that hold many freshwater species, such as walleye and muskie. Add a weedline in close proximity to a ledge or a drop and they can be prime spots.

A hump is a shallow area surrounded by deeper water and often a preferred piece of structure for bass. Humps are sometimes called underwater islands. A hole is the inverse of a hump – a deep pocket in the bottom surrounded by shallow water. Holes are favorite hiding spots of bottom-dwelling hunters, like catfish.

More Advanced Structures

The above items are some basic structures, but they also form the building blocks for more elaborate pieces of structures. What follows are some of the more common fishing structures, but this listing is by no means exhaustive.

One example is a spine. To imagine a spine, first picture an underwater hump as an elastic band. Take that band, stretch it slightly and you’ve got a spine. One of the most common places to find spines is as a continuation or off of a point from a shoreline, but others exist off the end of humps as well.

The contour of spines will vary, some even have fingers running off the sides of them, and their gradient, or slope, will also vary from steep to subtle. Like a hump, spines are surrounded by deeper water, with drops and edges on each of their sides. Long spines can be travel routes for fish as they move towards shore, transitioning from deep to shallow water.

The inverse of a spine is a cut, or trough, which can be described as elongated holes. Most common in flooded areas or reservoirs, many of these structures were streambeds in their former lives before water levels rose above their banks, submerging them. Of course, drops can sometimes contain cuts in their sides that are simply grooves that were not previously riverbeds. Again, these irregularities can attract fish and are worthy of fishing and their ledges can be particularly effective at holding fish or acting as route ways.

Still got that elastic? Holding both ends, bring them together slightly until the band bows. You’ve just created a saddle between two islands or underwater humps (your finger tips). Saddles can be great structures to fish with both deep and shallow water structures as well as being corridors for fish to follow as they move from one structure to the next. Depending on their disposition, fish may be anywhere on the saddle complex. They may be tight to the islands and feeding or positioned slightly off the saddle and inactive. In this case, it pays to know the behaviors of your target species and fish these areas accordingly, but when in doubt, pick the structure apart with different lures to work a variety of depths.

Another piece of structure is the breakline (sometimes shortened to break). A breakline is really just the edge of a drop that runs perpendicular to the shoreline. If you’ve ever trolled along the shore in an S-pattern, running between shallow and deep water, you’ve been fishing the breakline. Sometimes anglers will describe the different breaks as primary and secondary. The primary breakline is the first sharp drop in depth traveling from shore outward; the secondary following thereafter and another major drop in depth. Whether you think of breaks as walls or underwater stairs, they can be good structures to fish. Yet the entire breakline does not always hold fish. What makes them great fish-holding structures is when other elements (like a cut or a bend) or cover (such as a weed edge) are added to a stretch of the break.

Why is Structure Important?

Structure often concentrates fish. Structures provide different advantages to various species (such as corralling baitfish, providing an ambush area, or being close to deep water for comfort). For reasons like the three listed above, many species seldom stray far from structure. Learning how the fish you’re targeting relates to structure and being able to find structure on the water will increase your ability to catch fish. Structures can move you away from shorelines to intimidating expanses of water that may seem void on the surface, but what lies underneath can be fishing hotspots.

Putting Structure in Context

It’s important to keep in mind that structure is but one factor in the finding-fish equation. Finding structure can put you on fish, but it’s not an absolute that you’ll catch them. Structures are often feeding areas, but if there’s no food they’ll likely not hold fish. Weather conditions and seasonal patterns are also important to keep in mind and, again, are part of a larger equation to finding fish.

Other factors affecting if structures hold fish are temperature, oxygen supply, or water quality/light penetration. Since different species have different dispositions, some structures may appeal to certain fish and not others. For example, a 12-foot hump on a gin-clear, rock bottom lake may be a smallmouth bass hotspot, but too bright an area for walleye during the day. Yet at dusk and dawn it might concentrate light-sensitive walleye that move in to feed and ambush prey. Sometimes how well structures produce fish is all about timing and putting environmental and forage factors in your favor.

Using hydrographic maps and fish finders together can make finding structure a relative easy task.

How Fish Relate To Structure

As mentioned, food and environmental factors impact the mood of fish and thus, impact how they relate to structure. A common misnomer is that if fish are not directly on top of structure, they are not there or are not relating to it. Speaking in general terms, fish “on” structure are usually aggressive (add cover to the mix and things could change), while fish suspended “off” of structure are less aggressive or in a neutral mood, resting between feeding binges (unless baitfish are also suspended off the structure). Fish distanced from structure are still relating to it and catchable, so novice anglers should learn to fish both the actual structure as well as its surroundings. It pays to ask, “How do the fish travel to this spot? Is there an obvious route on my hydrographic map?” and “If fish are not directly on the structure, where might they be off of it?”

The Tools of the Trade & Finding Structure

As mentioned earlier, the easiest structures to find are those that extend from land, such as a point. The reason is obvious; one sees the gradual slope on land and knows this piece of structure likely continues into the water. What’s difficult is finding structure when there are not hints from land. This is where a fishing finder and hydrographic maps are critical.

Hydrographic maps illustrate the bottom contours and depths, showing where the structures are on a body of water. Of course the scale of the map will impact the detail of the features it shows. Depth finders are your underwater eyes. They provide a continual reading of the depth below your boat, and help you pinpoint depth changes and find structure. Using hydrographic maps and fish finders together can make finding structure a relative easy task, even on a new lake.

A recent addition to an angler’s arsenal are GPS units, which can hold hydrographic maps as well as store waypoints, allowing you to mark structure once you find it. Of course, carrying some buoys is also handy to help you stay on structure as you fish the entire area.

Tips for Fishing Structure

I won’t try and cover how-to fish the various types of structure in one article, but I will suggest a few tips. First off, working jigs along the bottom and around the edges of structure can catch several species of fish, anglers should not just concentrate on the bottom (whether using jigs or not). Consider trying lures to work other depths around the structures. Also, try and fish “off” of structure as mentioned earlier. By this I mean if trolling the breakline, weave out into deeper water to look for suspended fish. The same concept applies when casting areas, like humps, islands and saddles.

Here’s a tip: fish sometimes suspend off of structure around the same depth as the structure itself. So, a hump that’s 12-feet deep might have a pike several feet away from the edge of the structure, suspended at 12-feet over water with a depth of 25-feet. Another important tip, which I’ve touched on already, is learning to isolate prime structure by considering other factors influencing fish behavior (such as food, cover, environmental elements, and so on).

Once you’ve done your homework and found structure you think will hold fish – take the time and fish it thoroughly. Many anglers work large structures too quickly, and if a big trophy is relating to a certain, special area on the structure (often called “the spot on the spot”) you might pass over her.

Learning about structure is just another way of thinking to solve the “Where are the fish today?” puzzle. Use maps and read up on your favorite species and how they relate to structure and you’ll find yourself catching more fish. Large pieces of structure can be intimidating to fish, so take the time to look for the best areas (considering other fish-factors) and fish them thoroughly.
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Warmwater Lake and Pond Habitat Initiative

The Department’s fisheries biologists recently discussed the feasibility of installing fish habitat structures to mitigate for the absence or loss of physical fish habitat in some New Hampshire water bodies. This discussion was initiated because of the potential opportunity that exists to enhance warmwater fisheries through fish habitat improvement projects.

The overall goal of these habitat projects is to improve warmwater fish populations and the opportunities to fish for these species. An additional objective of installing shoreline habitat structures would be to increase youth fishing opportunities.

Improving fish habitat by installing structures has been a successful management strategy in use for many years in states across the U.S., as these structures can benefit both forage and sport fish populations in a number of ways. Habitat structures have been shown to provide important nursery areas for many fish species and can act to increase fish growth and survival. The abundance of forage fish species is often enhanced in areas with habitat structures, which in turn can increase the abundance and growth of sportsfish (this is especially relevant in some NH lakes and ponds where a decline or lack of forage fish and/or crayfish may be the result of the absence or loss of appropriate habitat). Additionally, studies have shown that habitat structures can increase nest density, spawning success and juvenile survival of both largemouth and smallmouth bass.

Using fish habitat structures in New Hampshire waters is currently in a conceptual phase and there is no firm timeline for when, where, and what types of structures will be used. Before formulating a specific plan, the Department’s fisheries biologist will first thoroughly review the existing scientific literature, inventory current habitat quality and quantity on various lakes and ponds, and communicate with anglers in an effort to better understand their interest in this type of initiative.

The Department is also actively pursuing a feasibility analysis of using fish habitat structures. The feasibility analysis will answer the following questions: Will fish habitat structures provide habitat for the fish species of interest? What types of structures have been used elsewhere and for what purpose? What types of structures (artificial or natural) are allowed under current regulations? What are the potential problems (maintenance, ability to obtain permits from NH DES, potential navigation issues, potential effect on other fish species such as invasive species) in using fish habitat structures? What are the costs of building, deploying and maintaining such structures? How will anglers use the fish habitat structures (i.e., how will they access them)? What monitoring efforts would be best suited for evaluation purposes?

Warmwater fish habitat projects offer an exciting opportunity to improve fish habitat and warmwater fisheries in New Hampshire lakes and ponds. Additionally, involving anglers in this process presents an excellent opportunity for the Department and anglers to work together towards the common goal of improving and sustaining our state’s fisheries resources for current and future generations.

CONTACT:
John Magee, Fish Habitat Biologist
Gabe Gries, Region 4 Fisheries Biologist and Warmwater Project Leader

Ohio Pond Management
Increasing Fish Production
Methods of Increasing Fish Production
Fertilization
Artificial Feeding
Adding Fish Habitat Structures

Pond owners should view their ponds as selfsustaining bodies of water that are capable of providing all of the ingredients necessary for good fish production. The amount of fishes that can be harvested depends upon a pond’s ability to produce them, and this amount varies from pond to pond. Ohio ponds can often support up to 250 pounds of fish per acre, although this amount is generally less for ponds that are smaller than one acre. If a pond’s normal fish production is less than what the pond owner deems acceptable, it may be possible to enhance production.

The most effective methods to artificially increase fish production are pond fertilization and fish feeding (pellet feeding pictured). However, each of these methods can also cause pond problems, so pond owners should consider them only after carefully weighing the trade offs associated with trying to increase fish production.

Fertilization
Fertilization can improve fish production by increasing the production of tiny plants and animals at the bottom of the food chain, the phytoplankton and zooplankton. This increase in production at the bottom of the food web may ultimately translate into improved growth and production of sport fish. However, negative impacts from fertilization can also result if the added nutrients stimulate growth of undesirable types of aquatic vegetation and algae. Whereas excess vegetation can be a problem to anglers and swimmers during warm weather months, it can also make the pond more susceptible to fish kills due to a build-up of dead and decaying plant material. The pond owner may find that the cost of fertilizer, effort to maintain a fertilization program, and risk of fish kills outweigh the benefits of the increase in fish harvested.

Most ponds in Ohio are adequately supplied with nutrients from the surrounding watershed and should not require artificial fertilization. In fact, many ponds receive so many nutrients from the watershed alone that problems develop with growth of excess vegetation and reductions in water quality. The following criteria should be met if a pond is to be considered for fertilization: 1) the watershed to pond ratio is less than 20 acres of watershed per surface acre of pond, 2) the watershed consists primarily of woodland acreage with soils that are low in fertility, and 3) the pond has a minimal amount of shallow water and most of the shoreline has the recommended 3:1 slope to discourage the growth of aquatic vegetation. Ponds without these characteristics should not be fertilized.

If fertilization is appropriate, then the pond owner needs to proceed with the proper treatment applied on a careful schedule. The recommended procedure is monthly applications of liquid fertilizers 10-34-0 (N-P-K) applied at the rate of two gallons per surface acre. Treatments should begin when water temperatures reach 60°F in the spring, and stop when water temperatures drop below 60°F in the fall. Fertilization should be temporarily halted when water temperatures exceed 80°F during the summer. Dilute each gallon of fertilizer with 10 gallons of water and spray the mixture evenly over the pond surface. Water clarity is a simple and convenient way to measure the progress of a fertilization program. The water clarity should be monitored twice each month throughout the fertilization season. This is easily accomplished by simply lowering a white object into the pond, such as a coffee mug on the end of a string. The white object should be visible to at least 18 inches below the water’s surface. If the object is not visible down to 18 inches, overfertilization may be a problem. In this case, postpone the next fertilizer treatment until the water has cleared somewhat and remeasure water clarity.

Artificial Feeding
Feeding is the most direct and reliable method to increase production of bluegills and channel catfish in ponds that are less than five acres. Proper artificial feeding will increase fish growth and provide larger fish for anglers. Unlike fertilization, with artificial feeding all of the nutrients go directly into fish production rather than the complex food chain. For ponds less than five acres, feeding is a feasible way to increase fish production. Bluegills and channel catfish will readily eat pelleted feeds that are available at agricultural feed stores. Pellet feed containing at least 25 to 32 percent protein will produce the best growth. Largemouth bass prefer live natural foods and will seldom eat pelleted feed.

Training fishes to accept artificial pellets may take a few days. When bluegills are feeding on the surface in the evening, tossing a few floating pellets into the areas where they are feeding will teach them to eat pelleted food. Begin an artificial feeding program by feeding fish about two pounds of pellets per acre per day. This amount may be increased to 15 pounds per acre per day after they have become accustomed to being fed. The feeding rate should be adjusted in the summer according to how much the fish are eating. Feeding may slow or even cease during the summer if water temperatures get above 85°F.

The best guide to feeding fishes is to give them no more than they can eat in 15 to 20 minutes. Using floating pellets in a feeding ring is a good way to monitor how much food they are eating. A feeding station approximately three feet in diameter can be constructed by sealing the ends of a piece of corrugated field tile. Connect the ends after sealing to form a three-foot circle and place the tile in an area of the pond that can easily be reached to fill with food (pictured right).

A pond owner should be willing to make a long-term commitment to continue feeding before a feeding program starts. Feeding should begin in the spring when water temperatures reach 60°F and should stop in the fall when water temperatures drop to 60°F. Fish should be fed daily at approximately the same time and in the same place. Missing a few days of feeding while on vacation will not cause problems if feeding is consistent during the remainder of the summer. Overfeeding fish can cause many of the same problems as overfertilization. Food that is not eaten by fish will decompose and use up the pond’s dissolved oxygen (see fish kills). Decomposing food can also release nutrients into the water that may promote the growth of aquatic vegetation and algae.

Adding Fish Habitat Structures to the Pond
Habitat structures –“fish shelters,” or “fish attractors”– are primarily designed to concentrate fish and increase an angler’s chances of success. Depending upon the size and type of materials used, structures can provide cover, resting areas, and feeding areas. Habitat structures can act as substitutes for natural cover in ponds where these types of areas are lacking.

Habitat structures can be constructed from many different natural and man-made materials. Easily obtained materials such as discarded Christmas trees can be banded together, weighted and sunk, although trees such as oak, hickory, and cedar work best due to their resistance to decay (brush pile picture right) . Man-made materials such as PVC pipe, field tile, concrete block, and wooden pallets can also be fashioned into fish attracting devices. Habitat structures can be placed into the pond from the bank if the structures are not too large and there is relatively deep water near the shore. Larger structures can be placed from a boat to allow access to deeper water.

Winter ice cover provides an excellent opportunity to build and place structures too large to install from the shore or by boat. These structures can be built on the ice, or built on shore and dragged out onto the ice. In either case, the structure is placed on the ice and allowed to fall into the desired location when the ice melts (see brush piles on ice to the right).

Fishes & anglers alike will make the best use of habitat structures that are distributed carefully in the best locations. These structures are best placed in water that is within reasonable casting distance from shore & two to eight feet deep to allow consistent fish use. Habitat structures should not be placed in the deepest part of the pond where low dissolved oxygen levels (common during summer) make them inaccessible to fish.

How to Build Fish Cribs for Habitat
The approximate cost of a crib is about $10.00 each, and now there is a new way to help purchase cribs for Lake Chippewa Flowage. In the summer of 2002 friends of the flowage will have the opportunity to purchase $10.00 raffle tickets. A drawing will be held in October and the lucky winners will be able to schedule a free day with a local fishing guide for 2003.
The Chippewa Flowage was created over 75 years ago. In those 75 years many trees and stumps that harbored food and shelter for fish have disappeared through natural decay. Realizing the structure must be replaced for a healthy fishery, the Lake Chippewa Resort Association, along with the Chippewa Flowage Area Property Owners Association started building and placing fish cribs in Flowage waters. Since March 1996 over 2500 cribs have been built and placed by volunteers from these associations. Building Cribs:

The first step is to accumulate wooden pallets. Pallets are donated by various companies in Wisconsin and trucked to the flowage at our expense. Cinderblock, clips and strapping must be purchased to build cribs. Cribs are constructed by layering pallets separated by cinderblocks on each comer until it is 3 or 4 pallets deep. Then the “sandwich” is strapped together. At this point the cribs are loaded by tractor-forklifts onto special pontoon boats that have been totally stripped down to just bare decks. Workers then turn the pallet/cribs on edge to stuff in brush. It takes a lot of brush to fill each crib. Accumulating brush and stuffing the cribs is actually one of the hardest parts of the job. Finally , when the pontoon is totally loaded, the captain and workers shove off and the cribs are dropped off into new crib locations.

Meanwhile other volunteers are cooking and serving food and beverages to the hungry workers. A master map is kept by the associations, but not published. After all, the cribs are for the fish, not the fishermen!

Crib building is an on-going project. Members of both associations are committed to preserving and enhancing this great fishery for current and future generations. If you are interested in supporting this effort, look for Crib Program Raffle Tickets on your next visit or mail donations to: CFAPOE Adopt-a-Crib P.O. Box 555 Hayward, WI 54843-0555

Read more at the Washington Examiner: http://washingtonexaminer.com/news/2011/04/calif-agencies-sue-over-sucker-fish-habitat#ixzz1KBj6L3I7

Columnist | Joe Mosby
Volunteer workers improve fish habitat in Lake Hamilton
Posted on 05 March 2011
By Joe Mosby
The old lament of “why don’t they do something about the fishing in this lake?” is getting an answer in several Arkansas bodies of water.
The “they” is a combination of federal agencies, state agencies and — the key ingredient — private citizens who volunteer their money and labor.
One strong example is Lake Hamilton, the heavily used impoundment on the Ouachita River at the doorstep of Hot Springs. Fish habitat structures are being fabricated and sunk in appropriate places in the lake.
“Build it, and they will come” has been proven any number of times in Arkansas waters. The Lake Hamilton project, which will go on for several years, is moving ahead under guidance of fishing veterans Ricky Green and Darryl Morris. They have a contingent of other volunteers working with them and with the help of the Arkansas Game and Fish Commission.
Brett Hobbs, a fisheries biologist with the Game and Fish Commission, said volunteers are also doing much of the habitat work on DeGray Lake and Lake Greeson.
Green, formerly of nearby Arkadelphia, was one of the top professional bass tournament competitors in the 1970s and 1980s. Morris operates Family Fishing Trips, a guide service focusing on crappie fishing, on Lake Hamilton.
Morris said, “We are making two types of cover with bamboo. One is 10 to 12 feet tall that we call a ‘condo,’ and one is 5 to 6 feet tall that we call a ‘casa.’ There are other types available upon request by donors.”
The components are a plastic drain pipe with holes drilled in it, cane or bamboo and a 5-gallon bucket that is filled with concrete to hold the rig in place underwater.
Lake Hamilton is an old lake, built in the early 1930s by Arkansas Power & Light Co. for power generation. All of its natural cover is gone, Morris said, and the structures being installed will partly restore cover.
Morris said, “The fish structures benefit bass, crappie, bream and baitfish. They will support the entire life cycle of the fish. The density of these habitats provides ample protection for fish fry and bait fish. Algae growing on (the structures) provide food for fry and baitfish. This reduces the mortality rate and increases recruitment of the fry and baitfish which in term increases the number of catchable bass, crappie and bream.”
The structures are not marked, Morris said, “but are put in strategic locations like coves and points where they will be easy to find with a sonar unit” (depth finder).
The bamboo-and-bucket structure has been used for several years with success on Lake Greeson, where Morris worked with fellow crappie guide Jerry Blake in putting numerous structures into that lake. The encouraging crappie catches on Greeson have become known around Arkansas fishing circles.
Morris said about the Lake Hamilton project, “This will be an ongoing project. We hope to do 200 or more per year. After about five years it will become a maintenance program to keep the cover in the lake.
Help is needed.
Materials for the fish structures cost money even if the bamboo or cane is free except for the labor in cutting and transporting it. Green and Morris have several volunteer workers to assemble the structures and move them by boat to the desired locations. But they can use more willing hands.
Money donated by cash, check or credit card goes into a 3-to-1 match of federal and state funds for sport-fisheries restoration.
Morris can be contacted by e-mail at captdarryl@familyfishingtrips.com. A website, www.lakehamiltonhabitat.org, has more information.