Spatial and Temporal Distribution of Spawning Effort for White Bass in Pool 4 of the Arkansas River

Spawning behaviors and dynamics of white bass Morone chrysops in the Arkansas River have not been documented.  An assessment of the population is needed to provide a scientific basis for management.  We sampled white bass during their spawning season in the 10 primary tributaries found within Pool 4 in the Arkansas River.  The pool was divided into three segments (upper, middle, lower).  Each segment had three tributaries.  Each tributary was sampled every third week during the spawning season to determine spatial variability.  One tributary (Caney Bayou), known to be occupied by white bass during the spawning season, was sampled weekly to document temporal variability of the spawn.  White bass were collected by boat-mounted electrofishing.  The catch per unit effort (CPUE) averaged (SD) 6.2 (16.9) fish/h across the pool.  The CPUE for Caney Bayou averaged 8.5 (20.3) fish/h.  Caney Bayou was the most utilized site, but other sites were also utilized during the spawning season.  Precipitation and temperature appear to influence spawning effort.  Once water temperature reached 13°C, white bass activity near tributaries increased.  In addition, there was a positive relationship between precipitation and the occurrence of white bass in a tributary.  Overall gender ratio was 1M:2F, while the gender ratio in Caney Bayou was 1M:3F.  Two indices of population size structure were calculated.  The PSD was 68.9 and the PSD_P was 53.7.  Average relative weight across all cohorts was 103 (23.5).  The average TL for age-1 white bass was 204 (31.5) mm, and for age-3 white bass was 353 (21.3) mm.  The oldest white bass collected was a 7-year-old.  Total annual mortality was 49.3% using a catch curve regression.  As habitat alterations occur and water allocations and releases are modified, understanding the critical habitats and conditions supporting favorable spawning and recruitment is imperative.  Sampling will continue in spring 2011.