The bass and other game fish in Clear Lake have drawn a reputation for being fat and heavy. Just about every fisherman remarks on how healthy the fish are right now. The reason behind their heavy bodies is because of the abundance of baitfish in the lake. There are literally millions of threadfin shad, silverside minnows, small crappie and a long list of other baitfish available to the bass.
Threadfin shad are one of the more easily recognizable baitfish and they got their name from the long, and thread-like final ray of the dorsal fin. They can also be distinguished by a black spot on their side just behind the gills. They are a member of herring family.
Threadfins are not native to California. The Department of Fish and Wildlife (DFW) first introduced the shad into San Vincente Reservoir in San Diego County in 1953. The purpose was to provide an open water forage fish for bass and trout. Since then, the shad have spread across the state and now just about every low-elevation lake holds threadfin shad. It is thought that the threadfin shad found in Clear Lake were transplanted here by fishermen from Lake Mendocino. The DFW originally stocked the shad in Lake Mendocino as food for the striped bass
Threadfin shad first appeared at Clear Lake in 1986 and within two years the shad had multiplied by the millions. They are a fast-growing but short-lived fish. They only live about three years. A threadfin can grow as much as an inch per month and can reach lengths of 6 inches although most are only 3-4 inches long. Shad as long as 5 inches have been found in the lake though it’s extremely rare.
Shad feed on plankton, which puts them in direct competition with other fish in Clear Lake such as silverside minnows, blackfish and hitch. The sheer number of shad can overwhelm the plankton population at times.
Shad spawn when the water temperature reaches 65 degrees. They have an unusual method of spawning. The spawning occurs most often at dawn and centers around floating or partially submerged objects such as logs, brush, aquatic plants and docks. Small and compact groups of shad swimming near the surface approach an object at a fast speed and at the last moment veer away while spewing their eggs and sperm onto the object. The eggs contain an adhesive so that they will stick to logs and other debris. The eggs hatch in three to six days. Each female shad produces 900-21,000 eggs.
Threadfin shad are a delicate fish. They have a low tolerance for cold water and when the surface temperature drops to 45-48 degrees most of them will die. They also can’t tolerate sudden changes in water temperature, which sometimes leads to massive die-offs.
It was thought that the cold winter of 1991 killed off all the shad in Clear Lake, but they reappeared in 1997 and DFW biologists feel they were either restocked into the lake by fishermen or a small population survived from 1991. Why the shad have appeared in such great numbers the past few years in Clear Lake is unknown. Biologists say it probably is because of an abundance of plankton and other microscopic life that the fish feed on.
Threadfin shad are an excellent forage fish for adult bass and catfish. They are high in protein and are easy for the predator fish to catch.
The shad can be used as bait for bass and other game fish but there are certain rules a fisherman has to follow to obtain them. They cannot be snagged. Throw nets are also not allowed to obtain the shad. What can be used is a dip net and there are dip nets manufactured especially for catching shad and other small baitfish. When placed in a boat’s livewell or an ice chest shad will only live only a short time.
Threadfin shad can be seen schooling around the docks at Library Park in Lakeport, Lakeside County Park, the docks at Redbud Park and anywhere along the Nice-Lucerne shoreline. They are an important food source for the birds living at the lake. Western grebes feed heavily on shad as do osprey, cormorants, herons, pelicans and even bald eagles. The otters in the lake also feed on the shad.
The existence of the threadfin shad in Clear Lake is just another mystery at the oldest lake in North America and one more reason why it is so special.
