Responses to Gizzard Shad Recovery following Selective Treatment in Walker County Lake, Alabama, 1996-1999

Abstract Gizzard shad Dorosoma cepedianum is an important prey fish that is capable of influencing both the upper and lower trophic levels in aquatic systems. Contrary to our predictions, during the 4 years after a selective reduction of gizzard shad in Walker County State Fishing Lake (WCL), Alabama, the sport fish population structure did not decline as gizzard shad abundance rebounded. Adult gizzard shad catch rates in electrofishing transects (g/h) increased annually, and we saw a concomitant reduction of the WCL zooplankton community over the 4-year period. Limnetic larval gizzard shad density was highest in the second postreduction year and declined during the third and fourth years. In years when larval gizzard shad appeared in limnetic larval fish samples before larval white crappies Pomoxis annularis, larval white crappie densities were low. Conversely, the density of limnetic larval sunfishes Lepomis spp. was unrelated to that of larval gizzard shad, probably because of the protracted reproducti...