Zero, one or more broods: reproductive plasticity in response to temperature, food, and body size in the live-bearing rosy rockfish Sebastes rosaceus

Patterns of reproduction, such as size-fecundity relationships used in models to assess fish populations, are generally treated as static through time and invariant to environmental change. However, growing evidence suggests that changes in ocean conditions, such as warming water temperatures and reduced primary productivity, affect life history traits, including reproduction. Under controlled experimental conditions, we documented reproductive plasticity in the live-bearing rosy rockfish Sebastes rosaceus in response to different temperature and feeding regimes, with maternal size as a covariate. Rosy rockfish occur throughout the California Current, a highly dynamic ecosystem for which increased environmental variability is predicted with climate change. Females produced 0-5 larval broods annually. Larger females had disproportionately higher fecundity than smaller females by producing larger-sized broods and a greater number of annual broods. Warmer water temperature decreased the time interval between brood releases, likely reflecting faster egg and larval development. However, warmer temperature did not increase the total number of broods, potentially reflecting a tradeoff with increased metabolic demand. Well-fed females had better body condition and higher annual fecundity compared to poorly fed females, primarily due to a greater number of broods. Conversely, females with poor body condition at the start of the reproductive season did not reproduce, providing possible evidence of delayed maturation at smaller sizes or skipped spawning at larger sizes. Reproductive plasticity (in terms of whether and how many broods are produced per year) in response to the environment likely contributes to high inter-annual variation in population larval production. Understanding the causes and consequences of reproductive plasticity is critical to developing sustainable management strategies and predicting population response to changing climate conditions.