Growth and mortality of prairie stream fishes: relations with fish community and instream habitat characteristics

Few studies have been conducted to describe the age structure, growth rates and mortality of fishes in small stream ecosystems. The purpose of this st udy was therefore to determine age structure, growth rates and mortality (i .e., total annual mortality and, age-specific mortality) of central stonero llers Campostoma anomalum, creek chubs Semotilus atromaculatus, red shiners Cyprinella lutrensis and green sunfish Lepomis cyanellus from 13 streams o n Fort Riley Military Reservation, Kansas, using incremental growth analysi s. Further, we were interested in determining the influence of fish communi ty and instream habitat characteristics on growth rates. The age structure of central stonerollers, creek chubs, and red shiners was dominated by youn g individuals (i.e., less than age 2); however, over 60% of the green sunfi sh were age 2 to age 4. Mean total annual mortality was > 60% for cyprinids and averaged approximately 44% for green sunfish. The age-specific mortali ty of central stonerollers and red shiners was generally less than 45% betw een age 0 and I and increased to over 85% for fishes greater than age 1. Fi sh community characteristics (e.g., catch per unit effort of trophic guilds ) and chemical habitat (e.g., total phosphorous) were not related to growth rates (P >0.05). Growth of central stonerollers was not significantly corr elated with physical habitat (P >0.05). However, the growth increments of c reek chubs, red shiners, and green sunfish were related to the amount of wo ody debris (e.g., total woody debris, log complex habitat; r >0.60; P less than or equal to0.05). The results of this study provide important informat ion on the population dynamic rate functions of cyprinid and green sunfish populations in small prairie streams. Furthermore, these data suggest that woody debris is important habitat influencing growth of stream fishes.