Captive and Wild Observations of the Courtship and Spawning Behavior of Guadalupe Bass Micropterus Treculii

The Guadalupe Bass Micropterus treculii is native to the Texas Hill Country of central Texas, and is threatened by hybridization with non-native smallmouth bass, M. dolomieu. Texas Parks and Wildlife Department developed a captive spawning program for Guadalupe Bass to counter the influence of hybridization. To identify potential mechanisms influencing hybridization in Guadalupe Bass populations, our objectives were: (1) characterize nesting habitat and behavior, (2) compare courtship behaviors in native and hatchery environments, and (3) identify behaviors influencing genetic diversity in offspring. During spring 2013, visual surveys and recordings were made at Gorman Creek, and at A.E. Wood Hatchery. Breeding-color patterns of males and females became more differentiated. Aggressive behavior of males included opercular flaring and jaw locking, and individual males courted multiple females syntopically at nest sites. Frequencies for several behaviors differed between hatchery and natural environments for both males and females. Behavioral sequences were similar in hatchery and natural sites, but transition probabilities differed. Potential mechanisms for hybridization were: similar reproductive color-pattern changes between species for males and females, female preference in both species for larger males, similar repertoires of reproductive behaviors, and monopolization of nesting sites and females by a few males.