Reproductive schedule and traits of Hybopsis amblops (bigeye chub) in the Flint River system, Huntsville, Alabama

The goal of this study was to ascertain a reproductive schedule and describe reproductive traits of Hybopsis amblops in the Flint River system in Huntsville, AL. Members of this species were collected from the Flint River from May, 2013 to July, 2014. The standard length (SL) of each fish was measured using digital slide calipers. Gross body mass (GBM) and gonadal mass (GM) were obtained using a digital balance. In adult fish, gonadosomatic indices (GSI) were calculated to aid in determining reproductive timing. Ovaries and oocytes were categorized into developmental stages. Total fecundity (TF) of each female was calculated from the number of oocytes found in each ovary. The average size of oocytes in each stage of development was defined by diameter measurements. A spawning season from March to June with peaks in April and May were indicated by mean monthly GSI values. The primary reproductive month was April as evidenced by a peak GSI value with the retrieval of more than 800 stage III mature and stage IV ripe ova from females collected that month. An absolute fecundity ranged from 90 to 2,566 oocytes. This study examined multiple relationships between SL, GBM, GSI values, GM, TF, and water temperature. GSI values were found to be independent of SL and GBM in both sexes. Total fecundity not strongly correlated to GSI values (R2=0.306; p < .0001). The strongest relationship was seen between TF and GM (R2 = 0.621; p < .0001). Similar trends were noted for the mean monthly water temperatures (ºC) and TF. This study provides baseline information concerning the reproductive schedule and describes reproductive traits in H. amblops. These data are important for future examinations into this population’s response to environmental fluctuations, allopatric population comparisons, and any conservation effort based on scientific data.