Reproductive Biology of Redbreast Sunfish in a Suburban Watershed of Metro Atlanta, Georgia

Urbanization of a watershed increases sediment load, nutrients, and metals, leading to altered freshwater biodiversity. Anthropogenic disturbances may select for adaptive traits in tolerant fishes, including adjustments in life history and reproductive behavior in response to a changing environment. The main goal of our project was to study the reproductive biology of redbreast sunfish (Lepomis auritus) in a highly impacted suburban stream near Georgia Gwinnett College, Lawrenceville, Georgia, USA. Sunfish were collected from the Yellow River watershed by backpack electrofishing from June 2015 until September 2016. Egg count ranged from 670 to 2643 (mean ± SE: 1355 ± 139), and egg diameter varied from 1.24 to 2.14 mm (1.75 ± 0.04). For mature females, mean gonadosomatic index (GSI) was 7.1% ± 0.7 and ranged from 1.7 to 12.4% during the peak spawning period (May–July). Ages of mature sunfish ranged from 1 to 6 years, with 38% of the sample comprised of young individuals (1–2 years old). Additionally, we observed a 1-year-old female that invested significantly in reproduction (GSI = 12.4%, 1788 eggs). Analysis of female GSI over time indicated that fish likely spawned from April to September, with the biggest spike in GSI occurring between May and July. Examination of egg counts indicated that individual redbreast sunfish might spawn more than once during the spawning season. Further work is needed to assess reproduction in relatively unimpacted streams for comparison.