One undisputable fact is that Clear Lake is loaded with juvenile bass right now. These are the fish that were spawned last spring and are between three to six inches long. If only a small portion of these fish survive the winter the lake will be literally awash with bass next year.
Of course, the big question is will they survive the winter?
The main factor on the survivability rate is if the young bass have enough food. Studies by fishery biologists have shown that a young bass five inches long must eat at least once every three days during the cold months or it will starve. A 10-incher can go without food between eight and 10 days while an adult bass can go for several weeks. The problem is that young bass don”t have the fat resources that larger fish do.
A number of years ago fishery biologist Phil Barrington and other biologists of the Department of Fish and Game (DFG) did a study to determine the survivability of largemouth bass during the winter months. They electro-shocked a number of juvenile and adult bass from Clear Lake. The DFG placed the bass in three separate tanks. The water temperature in one tank was kept at the ambient temperature, the second tank was kept 55 degrees and the third tank was kept at 40 degrees.
During the first part of the experiment only juvenile bass were placed in all three tanks. The bass were kept in the tanks for two weeks and fed small minnows. The juvenile bass in the warm water tank had a high survival rate. In the 55-degree tank the mortality rate was about medium, but in the cold water tank the mortality rate was nearly 100 percent.
Adult bass were then placed in the three tanks. The adult bass in all three tanks had a very low mortality rate. The conclusion was that the juvenile bass died because they became dormant in cold water and didn”t feed. They also had very little body fat to carry them through in the colder water.
During the cold winter months the metabolism of all fish slows down considerably. The fish then rely on their body fat to carry them through these periods. The experiment proved just the opposite for the adult bass. It was determined that an adult bass will normally carry enough body fat to last it through the winter.
Barrington said the other problem for the juvenile bass is that as their body functions slows down they become lethargic and are easy prey for the adult fish and water birds. Birds such as grebes, cormorants and other water birds feed on the young fish. Biologists say that only about 1 percent of the bass that are spawned survive to grow to 10 inches.
Juvenile bass will feed on zooplankton the first week or two after they have been spawned before switching to insects. Within a few weeks they begin to feed on small minnows.
The abundance of silverside minnows presently in the lake are a boon to the small bass. The problem is by January most of the silversides will be gone or have moved out into the deeper water. The young bass will then turn to small crappie or bluegill or even smaller bass for their food source.
Clearer than normal water could also spell trouble for the small fish. Plankton counts have been down at Clear Lake for several years. The plankton is vital for the young fish and it”s also a requirement for insect growth. Silverside minnows feed almost exclusively on plankton as do threadfin shad. These are the prime bait fish for the juvenile bass.
The severity of the winter also plays a major role in the survival of the young bass. If the winter is mild the survival rate will be high, however, if it”s a cold winter the survival rate will drop considerably.
Barrington says the good news is that it only takes a small percentage of the young bass to survive the winter to sustain the population. A typical female bass will deposit approximately 3,000 eggs in a nest during the spring. If only 30 of these eggs hatch and live to adulthood the population remains healthy.
