Clear Lake continues to amaze fishermen. No other lake is the country undergoes the changes that Clear Lake does and that is what is so special about the oldest lake in the world. The big news this year were the massive fish die-offs that began in July and continued until September. Thousands of dead fish of all species were observed along the shoreline from Nice to Clearlake Oaks.
There are dozens of theories on what killed the fish and they range from spraying chemicals in the lake to massive algae blooms. The recent poor fishing was blamed on the die-offs and results of recent bass tournaments tended to confirm that. The tournament anglers said they have never seen the bass fishing as tough as this year. The other factor is the color of the water. Throughout much of the lake the water color is either a dark brown or even blackish. Apparently the culprit proved to be the hot months of July and August when he air temperature rose to 100-plus degrees and stayed there for several weeks. This caused massive algae blooms, which in the end depleted the dissolved oxygen (DO) in the water. This had a major impact on the fish.
The future of the bass fishery on Clear Lake was considered bleak by many. That all changed this past weekend when fishermen were catching up to 50 bass per day. I fished with Chris Hurt of Novato on Saturday and we ended up catching and releasing 37 bass, which would have been unheard of a week ago. Other fishermen reported similar success. We caught all our bass near the docks in shallow water. Helping the situation was the water color, which changed from a dark brown to green with visibility of more than a foot. We also graphed a lot of baitfish in the shallow water.
Apparently the cooling temperature has helped increased the DO in the water. Whereas a month ago the DO reading is most of the areas was less than 1, the DO readings on Saturday were 5 to 6. Bass require a DO of at least 5 to survive. The higher the DO the more active the fish become. During the fish die-off I checked the DO in several areas from Nice to Clearlake Oaks and most of the areas it varied from 2 to as low as less than 1.
A good comparison of the effect on low DO readings to fish is similar to when a human climbs a really high mountain. Near the top of the mountain the oxygen level drops and the lungs becomes starved for air. The same thing happens to a fish when the DO levels drop in their favorite habitat.
One theory is that during the die-off many of the bass moved into the deeper water, which has higher DO levels. As the water cooled and the DO increased, the bass have since moved back into the shallow water to feed.
Even with the die-off that killed thousands of fish of all species, there are still millions of fish that survived. Clear Lake has more fish per acre than any other lake in the nation.
This is also the time of the year when the blue-green algae dies off. The algae is a plant and goes through lifecycles as do all other plants. During the spring and summer months the algae grows and blooms, but by November the algae dies and the water clears up. That is what is happening now. Few lakes in the world go through the annual changes like Clear Lake. During its history the lake has constantly changed. Some of the changes have helped the lake and others have hurt it. These changes will continue for thousands of years to come.
