Clear Lake is one of the most fertile lakes in the country. In fact, the lake holds more species of fish than any other lake in California — 10 native and 21 non-native to be exact.
Of these different species of fish, the largemouth bass is by far the most popular fish in the lake although that wasn’t always the case. The lake originally held 14 species of fish of which four are now extinct. Some of the species of non-game fish that were abundant a few years ago are now in a sharp decline. For example, the populations of the once-abundant Sacramento blackfish and Clear Lake hitch have been shown dramatic declines compared to historic levels.
All the game fish in the lake are non-native with the exception of the Sacramento perch. They include largemouth bass, white, channel and brown bullhead catfish, green sunfish, bluegill and black and white crappie. Creel surveys done in 1969 showed that crappie dominated with 39.9 percent, followed by bluegill (22.8 percent) and catfish (13.1 percent). Bass made up only .5 percent of the catch 52 years ago. By 2000, crappie made up less than 1 percent of the catch while bass had soared to 85 percent.
Thirty years ago 67 percent of a fisherman’s catch consisted of largemouth bass while bluegill made up 15 percent of the catch. By 1994, largemouth bass comprised 85 percent of the catch and bluegill had dropped to 2 percent.
One of the most common fish in Clear Lake the past five years is the threadfin shad. While it was never stocked into the lake by the Department of Fish and Wildlife (DFW), scientists believe fishermen transported the shad from Lake Mendocino to Clear Lake back in the 1980s to serve as a a bait fish for the bass. The shad population exploded in the lake within a few years. The DFW did stock Lake Mendocino with shad in the early 1980s as bait for the striped bass.
The other small non-native bait fish in the lake is the silverside minnow. The minnow was stocked in Clear Lake and Blue Lakes back in 1967 to control the Clear Lake gnat. Within one year they were the most numerous fish in the lake. The silversides also spread throughout California within a few years.
Whether or not the minnow had an impact on the gnat population at Clear Lake is debatable because the primary food for the silverside is zooplankton, not gnat larva. At the same time silversides were introduced into Clear Lake, the lake was also being sprayed with DDT, which could have killed the gnats. Silverside minnows and threadfin shad feed on the same zoo plankton. When one population explodes, such as the shad this year, the other species goes into a decline and that is what has happened this year. It’s the old story of food availability.
As for native fish, the blackfish makes up the highest number. The blackfish is actually known as the Sacramento blackfish and dates back to long before humans walked the shoreline or boated on the lake. They are native to Clear Lake and the Sacramento and San Joaquin drainages. They also were introduced into other waters in the state. This species of fish is popular with some people because of its superior eating qualities. In fact, for years the blackfish was commercially harvested on the lake and shipped live to restaurants in the Bay Area where they sold for as much as $4 a pound.
The native fish that has drawn the most attention recently is the hitch. This fish also has been around for thousands of years and once was one of the primary foods for the Pomo Indians that lived on the shoreline of Clear Lake. During the past 20 years the hitch population has plummeted and steps are now being taken to restore its population.
With a total of 31 species of fish (native and non-native) in the lake it just goes to show why Clear Lake is so special and must always be protected.
