The fact just about everyone agrees on about Clear Lake is that it”s constantly changing. This year the lake”s algae problem is different and there is a noticeable lack of various species of baitfish. For example, very few silverside minnows are being seen and no threadfin shad. Actually, there are very few baitfish of any species.
In past years silverside minnows and shad made up the bulk of the baitfish in the lake but two years ago the shad all but disappeared and this year the silversides are nowhere to be seen. The result is there are few water birds ? such as grebes, cormorants and white pelicans ? here to prey on the tiny fish. There are even fewer baby bass. Normally the boat ramps are loaded with juvenile bass between 2-4 inches, but not this year. Either there was a poor spawn or the young bass are hiding in the massive weed beds.
The silverside minnows were first introduced into Clear Lake in 1967 to control the Clear Lake gnat. The primary food for the silverside is plankton and they can overwhelm a lake. The silverside population rises and falls in relation to the amount of plankton. This year the plankton counts are down considerably, which apparently has had an effect on the silverside numbers. Young bass will feed on the silversides and they are an important food source for these fish between 3-5 inches.
Silversides often congregate under floating weed mats and the juvenile bass follow the silversides. In turn, the larger bass feed on the younger bass. That”s why you often see explosions in the weed mats as the larger bass chase and devour the younger fish. Fishermen capitalize on this behavior by casting a plastic frog to the mats and they often catch some huge bass. This year, because of the lack of silversides, there has been little frog topwater action.
The threadfin shad have experienced wild population fluctuations during the past five years. Three years ago the shad were everywhere and the bass gorged on them. The population crashed two years ago and last year only the occasional school of shad was seen. This year there have been no reports of any schools of shad.
Fishery biologists say threadfin shad are a mixed blessing for a lake. They are an important food source for adult bass because their bodies are high in protein. They are also easy for the bass to catch. When the shad were in the lake by millions the bass put on fantastic weight and 10-pounders were common. Since the shad population plummeted, the number of large bass has decreased. Biologists say the shad have a negative effect on the juvenile bass because their huge numbers decimate the zoo plankton. Bass fingerlings feed on the plankton and without the plankton many of these small bass starve.
The silversides and shad are also an important food source for the many water birds visiting the lake. When the shad were at their peak the grebe population numbered in the tens of thousands. As the shad population declined so did the grebe population. Even though there are grebes on the lake, very few are nesting and there are practically no young ones. Nature has a rule that says if the food source isn”t sufficient the grebes won”t nest.
In addition, the white pelican population is only a shadow of what it was a few years ago. Pelicans feed solely on young fish and eat up to 4 pounds a day. When the silversides and shad were at their peak the pelican population numbered more than 1,000 birds. This year there are fewer than 50 pelicans on the lake. The same applies to the cormorants. At one time the trees around the lake were loaded with these fish-eating birds. Today the cormorant population is less than a third of what it was five years ago.
Clear Lake goes through these fish and bird population cycles every few years. It”s always been “boom or bust.” A few years from now the shad, silversides and the birds will return in abundance. It”s the nature of the oldest lake in North America.
