Local Fish: The North Yuba Naturalist [7/15]

By Katie O’Hara Kelly

Rainbow Trout

The most common fish in the North Yuba River is the Coastal Rainbow Trout, which is native to California, but has been planted locally. The 61 mile long North Yuba River is planted in two locations by the California Department of Fish and Wildlife, in April and June. There are also non-native German Brown Trout, that swim up to spawn from Bullard’s Bar Reservoir. Occasionally you might also find a non-native Brook Trout that has flowed out from a higher elevation lake, during a spring high water. Years ago there were also lots of Sucker Fish, but the River Otters have apparently eaten them all!

Fish start as eggs which hatch into larvae. The larvae are not able to feed themselves, and carry a yolk- sac in their bellies which provides their nutrition. At this stage they are called “alevins”. In about 2-3 weeks, the alevins will develop to the point where they can feed themselves (mainly zooplankton), and are called “fry”. When they develop scales and working fins they are called “fingerlings”. At about 2-3 years of age they will have grown to 18-20 inches in length and have become mature adults, ready to reproduce.

Trout larvae

Trout eat a variety of aquatic insects, that fly-fisherman are always trying to imitate. The underwater nymphs you are most likely to find easily in the river are Caddisflies, Helgrammites or Dobsonflies, Stoneflies, Mayflies, Dragonflies, and Damselflies. There are also tons of insects they prey on that inhabit, frequently visit, or accidentally land on the surface of the water such as, Water Striders, Whirligig Beetles, Water Boatmen, Midges, and Crickets. Trout will also eat fish, worms, and crustaceans.

Stonefly nymph

In turn, there are lots of natural predators that eat fish, including River Otters, Minks, Common Mergansers, Osprey,and Great Blue Herons. The river is a complex ecosystem in a delicate balance. Hopefully the river and the critters that depend on it for food and habitat, will keep flowing during this incredibly HOT summer. Pray for rain!

Leave a Reply