Influences of temperature variations on the reproductive activity of red porgy (Pagrus pagrus)

This study evaluated the effect of temperature variations on the reproductive activity of captive red porgy (Pagrus pagrus) under a controlled thermal regime during four spawning seasons (2015–2018). Daily relative fecundity (fecundity) and percentage of viable eggs (egg viability) of daily spawning were evaluated in response to water temperature in a manner independent of days from the spawning onset using Generalized Additive Models (GAMs). Mean fecundity changed in a roughly bell-shaped manner with thermal change up to ~18.5 °C, with a peak at 16.6 °C. Fecundity dropped sharply when the temperature exceeded 18.5 °C, indicating ovarian regression. Egg viability increased almost linearly between ~15 and 18 °C. Within the same thermal range of spawning peaks (between ⁓15.5 and 17.5 °C), a significant dispersion of fecundity values was observed, with ovarian maturation and ovulation synchrony among females being maximal around 16.6 °C. This information on the reproductive responses of red porgy to variations in temperature would help to optimize reproductive control in captivity. Furthermore, this study provides important information for approaching the role of temperature variation as a driver of change in the reproductive dynamics of wild populations in the context of climate variability and change.