why is catching bass getting harder

[Matt Fly]

How does a lake maintain fertility with three years of drought, and these are man made lakes and resorvoirs.  Only one natural lake in the state of Tx.  Caddo lake, it was formed by an earthquake.  

RoLo, The lakes you mention are not man made, I do know that as a lake ages, it loses fertility if nothing is there to replace the old existing structure.   As droughts go, so does the tributaries that feed them.   Most lakes don't suffer droughts, but do serve as public water resorvoirs, and demand on metro areas specially in summer when water usage is required more.   Due to no rains, and water consumption up, alot of exposed banks in N/NE Tx right now.   Populations are not going to decrease, but increase more every year.  The growing need for more water sheds is in demand in states and metro areas where massive populations exist.     Check your rain fall totals for the last 50 yrs,  Mother nature has given us the normal amounts every year, some less, some more, it hasn't changed very much, what has changed is the population explosion and the need for more water.

[Matt Fly]

I choose a northern state to show the difference in growing seasons and fertility.

From the Mn DNR

Many anglers still believe that northern lakes-cool, deep, clear, clean-are the ones packed with fish. But actually, it's southwestern lakes that contain and produce the most fish per acre. A northern Minnesota lake simply can't produce as much fish as a similar sized southwestern lake, any more than an acre of land in St. Louis County can grow as much corn as an acre in Le Sueur County. A northern Minnesota lake such as Vermillion in St. Louis County produces about 8 pounds of game fish per acre, while a southern Minnesota lake such as Tetonka in Le Sueur County produces about 40 pounds of game fish per acre.

Why the difference? Because lake fertility is one of the most important factors limiting the number and size of fish in a lake. The more fertile the lake-up to a limit-the more fish per acre it can produce. That's because fertile lakes support more plant life, and plant life supports the entire food chain.

Minnesota's lakes range from the relatively infertile oligotrophic ("scantily nourished") Northern Minnesota lakes, which have steep, rocky shores and contain few nutrients, and are so deep that the sun can penetrate only a small amount of water, to the extremely fertile eutrophic ("richly nourished") southwestern Minnesota lakes, which are surrounded by rich farmland and are so shallow that sunlight can reach -and thus stimulate plant growth in-a relatively large percentage of the water mass.

Between two regions are the central Minnesota lakes, called mesotrophic ("moderately nourished").

One qualifier: Lakes can actually have too many nutrients and grow too fertile to support game fish. That's because the same plants that provide food and oxygen to the lake also consume oxygen when they die and decompose. Every few winters, thick ice and snow on shallow lakes block adequate sunlight from reaching plants, which then die. As the vegetation decomposes, it uses up dissolved oxygen needed by fish to survive. When fish die in large numbers in late winter from lack of oxygen, it is called winterkill. This commonly occurs on overly fertile southwestern lakes and ponds.

[RoLo]

"Drought" is an unusual situation, and when it occurs, it affects natural and manmade lakes alike.

Floridian examples of drought include Johns Lake, Orange Lake and Lake Lochloosa.

When a drought lowers the water volume in a lake, it reduces the lake's ability

to dilute human waste, composted aquatic vegetation and phosphates (which are all fertilizers)

Human overpopulation likewise increases water fertility. When I lived in Georgia, the population

explosion in Atlanta overfertilized the Chattahootchie River and the headwaters of West Point Lake

where it enters. This was due to more people, more lawn fertilizer, increased agricultural phosphates

and last but not least, more fecal coliform.

[Matt Fly]

The south doesn't need to add nutrients on most cases.  But does need to provide a new source of cover once the new has worn off.  Banks and shoreline erode the cover.   New cover must be inplace for fry to survive.   Droughts that kill vegitation because of 20' drop in water levels need new vegatation introduced for new oxygen supplies or newly heavy growth on the uncovered shorelines.

This study comes from the "show me state" Mizzou and Iowa.

In Missouri, reducing nutrient inputs is central to our efforts dealing with nonpoint source pollution. Though it seems counterintuitive, some lake managers in the U.S. intentionally put nutrients into lakes, a process known as lake fertilization. By fertilizing, lake managers hope to increase the harvest of sport fish that lake users spend so much time and money to catch.

Fish yield and lake trophic state are highly correlated, meaning that greater nutrient concentrations in a lake equate to greater fish biomass. Adding nutrients to a lake will directly increase the amount of algae present, and the algae in turn provide food for zooplankton, many of which become food for fish (see the article Bottom UpTop Down).

People love to catch big fish, but before you decide to pour your lawn fertilizers into the lake, read on. Lake fertilization is generally only recommended in a handful of U.S. states where soil fertility is very low and fishing pressure is high. In addition to fertilization, some U.S. lakes are so acidic that lime must be added to increase both the pH and the chemical availability of the phosphorus. In acidic water, any added phosphorus will quickly bind with sediments on the lake bottom. Typically, Missouri lakes aren't blessed with the problem of too little algae, and our abundance of limestone generally ensures that the pH is high and phosphorus is readily available to algae.

Fertilization efforts are expensive and labor intensive. Fertilized lakes must be monitored frequently and fertilizer needs to be applied multiple times per growing season to provide a stable environment for fish populations. The heavy biological loads associated with fertilization require careful attention to dissolved oxygen concentrations. To avoid fish kills in cases of very high fertility, aeration may be required.

Fertilization is really only a viable option for lakes where fishing is the primary use. Swimmers, divers and municipal water users would certainly be upset to find that considerable money was spent to turn their lake into a green algae soup! Considering a lake's existing uses is important for any management plan, and favoring one lake use (fishing) to the exclusion of another (swimming, water supply) may not be legal.

The level of fish biomass that a lake can support is ultimately determined by the lake's fertility. The concentration of chlorophyll (the algal pigment measured by the LMVP), is one measure of lake fertility. In a study of Missouri and Iowa lakes, Jones and Hoyer (1982) showed the concentration of chlorophyll explained about 83% of the variation in fish harvest.

A 2004 study of Iowa lakes by Egertson and Downing shows that Catch Per Unit Effort (measured as weight of fish caught in a net each night) increases as chlorophyll concentration increases. However, with the increase in algae, the species of the fish captured shifts from traditional sport fish to benthivorous (i.e. bottom feeding see page 5) species like the common carp and the black bullhead. So, a lake with more algae can support more fish than a lake with less algae, but those fish may not be the desired species.

Ironically, in some Northwest U.S. waters, human activities have resulted in too few nutrients. Salmon fry hatch in fresh waters and grow as they move downstream to the sea. After a few years, the salmon have grown large by feeding in the ocean, and they return to freshwater to spawn and die. Historically, most of those salmon bodies would rot in the stream or lake, depositing nutrients in the process. As human fishing pressure has increased, more and more nutrients are taken out of the water as fish meat, leaving inadequate nutrients in the stream to support the flora and fauna upon which the salmon depend. For this reason, fertilization programs have begun in some northwestern lakes.

[Go Big Orange]

( in fact on one of my trips to Toledo Bend I had to go to a repair shop on the Lousiana side and the man that owns the shop has a stringer of bass he caught in the early 70's of 10 bass for a total weihgt of 108 pounds! and two other stringers with similiar days on the water. )

Maybe thats the problem too many lunkers hanging on a stringer instead being released.  >

I dont know if you have size limits there but we do 15" to keep which I dont keep I take a picture and throw em back. But I saw a show on how a 15" limit can have negative effects. They said limits like that tend to make the lake produce fish of 15" or less. Kinda corresponds to the poll on the main page.