Demographic characteristics of female mottled sculpin, Cottus bairdi, in the Coweeta Creek drainage, North Carolina

Synopsis We quantified: (1) growth rate, (2) length-mass relationships, (3) size- and age-specific fecundity, (4) egg size-frequencies, and (5) size- and age-specific egg diameter relationships for reproductively active female C bairdi from one of the southern-most extant populations of this species (Coweeta Creek drainage, North Carolina). Gravid females were collected during February and March in 1993-1995, and 1998. Cottus bairdi reached an age of 7+ and 79 turn standard length. The youngest and smallest gravid female collected was a 41 mm 1+ individual. Mature 1+ females were not uncommon and we collected 21 during our study. All females older than age 2 were mature. Mean fecundity for C bairdi at Coweeta was 71 eggs (range 9-166 eggs). We found significant positive relationships between fecundity and female length, weight and age. Female length and weight also significantly affected mean egg diameter, although the relationship was not linear. Neither female size or age significantly affected mean maximum egg diameters. Female C. bairdi from the Coweeta Creek drainage possess a unique suite of reproductive characteristics that may represent adaptations to the local selective regime or ecophenotypic variation.