Factor Analysis of Associations of Fishes in Little River, Central Texas, with an Interdrainage Comparison

Abstract

Species associations among 31 spp. of fishes in the Litte River, a large tributary of the Brazos River, central Texas, were examined using factor analysis of coded species abundance data for 184 collections. Separate analysis of correlation between 14 habitat variables vs. abundance data for the 5 spp. most closely associated in each factor resolved by the analysis gave insight into the major determinants of association among species. Collections with high scores for Factor I (channel catfish group) were concentrated in larger permanently flowing channels of the drainage. The distributions of collections with high scores for Factors II (orangethroat darter group) and III (fathead minnow group) were complementary, with the former concentrated in clear, hard-bottomed streams and the latter in turbid waters of sluggish streams of the Blackland Prairie region. Collections with high scores for Factor IV (longear sunfish group) were concentrated in permanent pools of tributaries and headwater streams throughout the system. Comparisons of the results for the Little River with those of a similar analysis of another river system demonstrated that, even in very different streams, similar species tend to assort into similar species associations.