| Abstract | A study of the biology of the rare Modoc sucker (Catostomus microps) was undertaken in Modoc and Lassen counties, California, in 1973. It appears to require small partially shaded streams with large muddy bottomed pools and is eliminated when the streams are channelized. Even where abundant, it is a minor part of the total fish fauna present. Their abundance was positively correlated with that of speckled dace (Rhinichthys osculus) but negatively correlated with that of brown trout (Salmo trutta), Pit sculpin (Cottus pitensis), Sacramento sucker (C. occidentalis) and Sacramento squawfish (Ptychocheilus grandis). Their feeding habits and growth rates are similar to other members of the genus Catostomus, although they seldom grow larger than 15 cm SL or live longer than five years. They achieve maturity in their second or third year, spawning in April and May. Their small numbers, concentration in a few small streams, and susceptibility to channelization and hybridization with Sacramento suckers indicates they should continue to be managed as a threatened species. |
