Gonadal development and sex-specific demographics of the shovelnose sturgeon in the Middle Mississippi River

Abstract

Summary Harvest of the shovelnose sturgeon, Scaphirhynchus platorynchus for caviar has increased. To determine whether populations can withstand increased harvest, detailed information regarding sexual demographics is needed. We describe gender and reproductive development of 306 shovelnose sturgeon from the Middle Mississippi River (River km 0–322) during September 2001 through December 2003. Using dissection and histology, we identified three of the four gonadal stages described previously for male lake sturgeon and all seven stages for females. Males reached maturity at a smaller size than did females. Gonads can be rapidly inspected for sex and stage of development for the shovelnose sturgeon. The sex ratio was not different from 1 : 1. Seven intersexual fish occurred. Female fecundity was positively related to body weight (number of eggs ¼ 30.24 · body weight ) 8392; P ¼ 0.013; r 2 ¼ 0.45) and weakly related to fork length (number of eggs ¼ 146.37 · fork length ) 66 176, P ¼ 0.053, r 2 ¼ 0.23).