Reproductive biology of blue sucker in a large Midwestern river

Abstract

Efforts to protect or rehabilitate depressed blue sucker Cycleptus elongatus populations require an understanding of life-history characteristics and reproductive biology to provide fisheries managers with the tools required for science-based management. The objective of this study was to examine the reproductive biology of blue sucker in the Wabash River, Indiana, during March and April 2006. A total of 105 reproductively mature blue sucker (53 males, 52 females) was collected using boat electrofishing to examine size-at-maturity, absolute fecundity, gonadosomatic index (GSI), relative fecundity, and estimated egg size. Size-at-maturity was estimated at 515 mm total length (TL) for males and 568 mm TL for females. Mean absolute fecundity of females captured during the study was 150 704 eggs per female (range, 26 829–267 471 eggs per female) and was positively related to both TL (r2 = 0.66) and wet weight (r2 = 0.77). Mean GSI was 6.4% (range, 2–9.3%) for males and 17.2% (range, 4.3–23.4%) for females. Relative fecundity ranged from 15 331 to 65 887 eggs kg−1 body weight (mean = 46 946 eggs kg−1 body weight) and was strongly correlated with GSI (r2 = 0.87). Mean estimated egg size was 278 eggs g−1 (range, 229 364 eggs g−1) and exhibited an inverse relationship to GSI (r2 = 0.42). The results of our study provide information on the reproductive biology of blue sucker which can be used to aid in the identification of potential recovery threats for depressed populations.