Alosa to detect ultrasound (at frequencies above 20 kHz, which is the limit of human hearing). This was first discovered by fisheries biologists studying a type of shad known as blueback herring, and was later verified in laboratory studies of hearing in American shad. This ability is thought to help them avoid dolphins that find prey using echolocation. "Alosa" species are generally pelagic. They are mostly anadromous or semianadromous with the exception of strictly freshwater landlocked species. "Alosa" species are generally migratory and schooling fish. Males usually mature about a year before females; they spawn in the late spring to summer.
Fox River (Fish River tributary) tributary of Fox River, known as Blue Rock Creek. I X L Gulch is a small tributary which heads about a mile southwest of Fox River. Slate Creek is another tributary, from the south. Along Fox River, about south of Council, there are several dikes of greenstone that under the microscope are found to be slightly altered diabase. They consist of labradorite and olivine phenocrysts in a groundmass of plagtoclase, augite, and biotite. Some greenstone masses which appeared to be slightly altered tuffs were found in the divide between Fox and Solomon rivers. Fox River (Fish River tributary) Fox River