Success, Failure, or Somewhere in Between: Assessing Genetic Restoration of an Endemic Black Bass Population

From 1992 to 2010, Texas Parks and Wildlife Department undertook a long-term stocking program with the aim of restoring the genetic integrity of Guadalupe Bass Micropterus treculii in the headwater streams of its namesake river.  At completion of the program, hybridization with the introduced Smallmouth Bass M. dolomieu was significantly reduced throughout the study area (From 20 - 100% in the 1990s to 0 - 24.2% upon cessation of stocking).  However, the future stability of the population’s genome was uncertain due to persistence of hybrids in the system and variable genetic trends observed in other hybridized populations.  Now, seven years since the cessation of stocking, three follow-up genetic surveys have been conducted.  We observed an initial, dramatic increase in hybridization rates one year post stocking in three of the four study stream segments.  Since then, trends in hybridization rates have been variable among stream segments.  These data suggest that variable biological and ecological factors among stream segments may affect survival and reproductive behavior, ultimately structuring the population’s genome.  These results are important for guiding current and future restoration efforts in other streams within its historic range and may help guide similar restoration efforts for other hybridized centrarchids.