Sacramento pikeminnow

The Sacramento pikeminnow (Ptychocheilus grandis), formerly known as the Sacramento squawfish, is a large species of freshwater ray-finned fish belonging to the family Leuciscidae, the daces, chubs, Eurasian minnows and related species. This species is endemic to California in the United States. It is native to the Sacramento-San Joaquin, Pajaro-Salinas, Russian River, Clear Lake and upper Pit River river basins. It is predatory and reaches up to 1.4 m (4.6 ft) in total length.

The species has been introduced into the Salt River, where it is considered an invasive species.

The species was introduced to the Eel River watershed in the 1970s by anglers using the pikeminnow as bait. It has a large appetite for salmonid species once it reaches about 6 inches (15 cm) long. Until then, it eats anything in its path. Because it is invasive in the Eel River, it has very few predators. River otter populations have increased and helped stabilize the pikeminnow population, but they still put pressure on endangered salmonid species.

Distribution

Sacramento pikeminnow is a common widely distributed species that is native to California.

Its natural distribution includes low and middle elevation run of the Sacramento-San Joaquin Province, the Clear Lake Basin and the Pajaro-Salinas and Russian river systems. They have also been introduced into the Eel River, Morro Bay tributaries and Southern California reservoirs. It is, however, uncommon in the freshwater Delta region. The species introduction resulted from juveniles released as bait fishes or in stocked gamefishes.

Behaviour

The diet of Sacramento pikeminnow is diversified including freshwater and estuarine invertebrates and fish species. Juveniles smaller than 10 cm (3.9 in) fundamentally feed on insect larvae and aquatic invertebrates. As they grow, the focus of their diet shifts to crustaceans and then fishes. There is considerable overlap in the diet of this species and Striped Bass. Both are opportunistic feeders that prey on seasonally available food including chinook salmon, minnows and sculpins. They even prey on frogs, large stoneflies, lamprey ammocoetes, and small rodents. This piscivorous species is known to also feed on its own young. And so, the juveniles tend to inhabit more sheltered areas to avoid predation threats.