Bass Biology 101: Stocking Practices
September 24, 2010
A top bass biologist shares his insights into stocking practices and what can be done to maintain our top bass fisheries.
Photo by Ron Sinfelt
by Scott Robinson
"Man, we didn't catch a thing all day! The state needs to stock more bass in this lake," is a comment that can be heard on a regular basis from bass anglers at just about any lake, and at first glance it seems to make sense. Put more fish in the lake and there will be more fish to catch, right? But if all that was needed to produce better fishing was to stock more fish, the fish hatcheries in this country would be much larger and more numerous than they are now.
State and federal agencies, universities and private lake managers around the country have been working for over 100 years to produce the best fishing possible in both public and private waters, so if stocking fish was the perfect answer, it would be done on a much grander scale than what exists now.
While stocking fish is not always the answer, particularly in the case of largemouth bass, there are some great bass stocking stories that have produced results over the years. On the other hand, there have been instances where considerable time and effort has been invested in stocking programs that did not produce the desired results. The unsuccessful stocking attempts provide guidelines for what not to do next time.
Just as long as we don't keep making the same mistakes over and over, all is not lost, even when things don't work out. There are many intriguing research and experimental stockings going on right now that may have a big influence on bass fishing in the future. Here's why and how bass are being stocked today, and where past and current stocking efforts may lead fisheries management and fishing in the years to come.
Bass are stocked for several different reasons. Experimental stockings include stocking bass of a particular size, sex, or number, or even a new genetic strain of bass, then tracking their performance and impacts in the stocked water. Many of the most successful stocking efforts in the US were developed after experimental stockings, both successful and unsuccessful, were used to refine stocking techniques and determine the likelihood of success in a particular situation. Experimental stockings also offer the opportunity to determine if a stocking is cost effective or not. Generally speaking, bigger bass survive better after stocking than smaller bass, but bigger bass cost more and take longer to produce in hatcheries. Since hatchery space and other resources are always limited, one question that must be considered is "Do we stock more small bass or fewer bigger bass?" That question and many others can be answered with experimental stockings. The trick is that each water body is unique, so stocking programs on any body of water must be tested and periodically evaluated.
One of the most interesting bass stocking experiments going on right now is Texas Parks and Wildlife Department's introduction of triploid largemouth bass. These are bass that have three sets of chromosomes instead of two (hence the term triploid), so they are effectively sterile and will not reproduce. Triploidy, as it is called, is often used in fisheries management to produce sterile fish. The two most common methods of producing triploid fish are by heating the eggs or placing them under high pressure after they are fertilized; the resulting fish that hatch from these treated eggs are triploid and unable to reproduce. The hope is that bass that do not reproduce and do not spend the time and energy necessary to spawn will grow faster and larger than bass that do spawn. This technique may also offer the opportunity to stock a genetic strain of bass that, because they are sterile, will not interbreed with the existing bass population and change the genetics of it. The jury is still out right now, and this is definitely an experimental stocking at this stage, but the possibilities exist for producing big bass and refining bass management using this technique.
Other situations where stocking bass has been successful include new lakes, lakes that have been renovated or drained, or lakes where many or all of the bass have been killed by natural disaster. In recent years, several southern states have lost bass populations to fish kills caused by hurricanes, tornados, and floods, and in these cases bass have been successfully restocked to help speed up the recovery process and bring balanced, fishable populations back to the lakes as quickly as possible.
In new lakes, bass are stocked to establish an initial population that will eventually reproduce and become self-sustaining. This is also an opportunity to kick start the fishing in a lake by stocking a fast growing genetic strain of bass. Typically bass grow pretty fast in new lakes where the forage fish populations are expanding, and introducing bass at the right time can produce some phenomenal catches. One small public fishing lake in Georgia has recently produced several bass well into the teens, including a 15 1/2 pound bass last spring and a 13 and a 14 pound bass in one day by the same angler, as well as numerous bass over ten pounds. Most of these huge bass came from the original stocking of bass fingerlings raised in state hatcheries and stocked in the lake about six months after bluegill were stocked for forage fish. On the other side of the Mississippi river, that famous lunker factory Lake Fork in east Texas was stocked in a more indirect way. Florida bass, with the ability to grow larger than the native northern strain bass of Texas, were stocked in ponds in the basin of the lake before the lake itself filled up. As the lake filled up and flooded the ponds, these Florida bass and their offspring found thousands of acres of new habitat filled with tons of food, and boy did they ever grow!
So at this point, if your favorite lake doesn't receive stocked bass, you might still be asking "Why don't they stock more bass in my lake now?" The answer lies in the nature and biology of bass. Largemouth bass are prolific spawners. Each female can produce hundreds or even thousands of eggs. The males, of course, fertilize the eggs and then vigorously guard the nest and it's precious contents against predators. As a result, one pair of bass can easily produce several hundred offspring that survive to fingerling size. Many of those will live to adulthood if food, space, and habitat are available. However, the competition for food and space is fierce in the bass's underwater world, and that competition is usually the limiting factor that keeps bass populations from being any larger. In most southern lakes bass reproduction is plentiful and successful, so stocking more bass is like pouring water in a bucket that is already full. The bucket will only hold a certain amount of water, just as a lake will only support a certain number of bass. When we add bass to these lakes they often don't survive, or if they do, they simply replace bass that were already there. In such cases stocking bass is not a wise use of the limited time, money and effort of state fisheries agencies. However, suppose we could add bass that grow a little bit faster, reach a larger
maximum size, or strike lures a little more often than the existing bass. When that is the case, then stocking bass is not a waste of time and resources after all, which brings us to the Florida bass story.
No article about bass stocking would be complete without mentioning the success of Florida strain bass introductions west of the Mississippi river, outside the natural range of the Florida bass. California, Texas, Oklahoma, Louisiana, Arkansas and other states have all experienced dramatic increases in the size of bass available to anglers after Florida bass were stocked. Texas' largemouth state record stood at just over 13 pounds for nearly fifty years, yet in 1980, just eight years after Texas Parks and Wildlife Department began stocking Florida bass in the state, the record was broken by a 14 pound Florida. From that point on the record climbed steadily until the 18 pound mark was topped in 1992 with a Florida strain bass from Lake Fork. Other states saw similar results, although not all were as dramatic as the results in Texas. Obviously, Florida bass grow larger than Northern bass in some situations, and Florida bass stockings have resulted in anglers having a much better chance of catching a trophy size largemouth. They have also generated a lot of excitement for anglers and brought increased business from fishermen to lakes in each state.
Biologists have found, however, that the stockings must be continued year after year to maintain the trophy bass production and the level of Florida bass genetic influence needed to grow the big ones. When Florida's are not stocked on a regular basis, northern bass genes begin to dominate the population again in most lakes. Today millions of Florida bass are stocked each year in lakes all over the south in an effort to produce bigger and faster growing bass.
All these Florida bass stockings don't come without a downside, though. Florida bass have a reputation for being lure-shy and tough to catch. Researchers in Texas documented that Northern strain bass tend to be more easily caught, or aggressive, than Florida bass. The Alabama Game and Fish Department has shifted away from stocking Florida bass in all of its public fishing lakes because the bass fishing simply got too tough. Even though electrofishing surveys showed plenty of nice bass, fishermen just weren't catching them. It seems the Florida bass is much more likely to have a stubborn case of lockjaw than the Northern bass, and if you stock too many in one lake you may not catch any thing at all.
East of the Mississippi river the Florida bass' genetic influence shows up naturally in populations as far north as Maryland. Generally though, anywhere north of the Florida-Georgia border the native bass are actually intergrades, or natural hybrids, of the Florida and Northern strains. More Florida genetic influence shows up in the southern end of this range, and moving north the Northern bass genetic influence becomes stronger and stronger until you eventually find pure Northern strain bass again. There are also pockets of pure Northern strain bass in some regions south of Maryland. Biologists have debated over whether stocking Florida strain bass would provide any benefits in areas where Florida genes already exist, and the general consensus is that it won't provide the dramatic differences seen farther west. In fact, Florida bass have been stocked in numerous locations throughout the southeast, and nowhere have we seen results like those achieved in the western states. However, most of the state records for largemouth east of the Mississippi have been well into the teens for years, and of course the world record 22 pound, 4 ounce bass came from south Georgia, so there really isn't a whole lot of room for improvement as far as state records go in most southeastern states.
Anglers and biologists in these states haven't given up on improving the genetics of their bass populations though. Tennessee recently began a Florida bass stocking program in several lakes in an effort to give their bass populations every 'boost' possible. Georgia and Alabama have been conducting experimental stockings with an F1 hybrid largemouth. The F1 is the first generation offspring of a female Florida bass and a male northern bass. The F1's are touted as having some of the best qualities of both strains - the aggressiveness of the northern bass and the faster growth and larger size of the Florida bass, combined with a good dose of hybrid vigor. An F1 bass in Alabama was reported to grow to a fantastic 7 1/2 pounds in just 27 months. While an aggressive, fast growing, large bass sounds like a dream come true, the jury is still out on whether or not these fish will truly make a difference in large reservoirs.
One other situation exists where bass are being stocked successfully, and that is when bass are present but successful reproduction and survival of young bass is limited for some reason. It may be because of a lack of suitable spawning and nursery habitat or a lack of suitable size forage that small bass need (usually aquatic insects and larval fish). It may even be due to high numbers of a predator that eats baby bass, such as adult blueback herring. In cases such as this, bass can be grown in hatcheries until they pass the critical stage in their lives where the bass in the lake aren't surviving. For instance, blueback herring have recently been introduced in some southern lakes, probably by live bait fishermen who released their bait at the end of the day without realizing the consequences. In lakes that don't have a lot of shoreline cover, adult blueback herring can prey heavily on largemouth bass fingerlings, and young blueback herring compete directly with the young bass for food. In this situation, stocking bass three or four inches long that are too large for blueback herring to eat may eventually increase the number of adult bass in the lake and improve the bass fishing.
Another southern lake, Lake Talquin in Florida, has very little vegetation and shoreline cover, but there is food available for adult bass. Bass spawned and hatched naturally in the lake have been found to hatch too late to take advantage of an early spring shad spawn, and when combined with the lack of shoreline cover and vegetation this results in poor survival and growth of naturally spawned bass. In this situation, bass three to four inches long are stocked early in the spring season, when they can take advantage of the shad spawn and grow quickly. These stocked fish have survived well, grown better than wild fish that spawn too late in the season, and comprised as much as forty percent of the existing bass population in the lake. This is definitely a successful bass stocking scenario, and one that is likely to be continued for years. Talquin is in direct contrast with Norris Lake in Tennessee, where biologists stocked 9,000 tagged, largemouth bass five to eight inches long. Three electrofishing surveys over the next year failed to produce a single tagged largemouth bass, and researchers rightly concluded that the situation was unsuited for bass stockings.
As you can see, bass-stocking success varies widely across the south and even from lake to lake. Success also depends on the goals of the stocking program. Stocking programs intended to increase the numbers of bass in a population are usually only successful when some other factor, such as predation or lack of suitable habitat, severely limits the number of bass fingerlings that survive to adulthood. Generally speaking, the most successful stocking efforts have been those that seek to enhance the genetics of an existing bass population to provide faster growing, larger or more aggressive bass. The
end result of these stockings is not more bass to catch, but hopefully bigger or more aggressive bass for fishermen.
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