The effect of temperature on sex determination in Yellow perch was examined across two generations. The first set of experiments, previously presented in 2019, evaluated the effects of low (14°C) and high (27°C) temperature on the survival, growth, and resulting sex ratio of Yellow perch progenies (n=11) when exposed during the labile period of sex differentiation (when fish are 12-30mm total length). Sex ratio results obtained from 2 year-old fish suggested a masculinization effect of high temperature in 6 of 11 progenies exposed. Yellow perch males from this first set of experiments (F1) were used to sire an F2 generation. This F2 generation, consisting of 15 progenies from 13 different F1 sires, was then used in a second set of experiments that evaluated the effects of low (14°C), medium (23°C), and high (27°C) temperature exposure applied for 84 days from the start of first exogenous feeding.
Effects of temperature on survival and growth of the F2 progenies were evaluated throughout the temperature exposure, as well as through the first year of grow-out. Effects of sire’s temperature exposure and the interaction of the progeny’s and sire’s temperature exposures on the growth and survival of the F2 generation were also evaluated. Survival did not differ significantly between progeny of different temperature treatments at majority of the sampling points in the F2 generation.
There was a significant effect of progeny temperature treatment and sire temperature treatment, independently, on the growth of F2 progeny. During the temperature exposure phase, both medium and high temperature progenies weighed significantly more than low temperature exposed progenies. After the temperature exposure phase, high temperature groups weighed significantly more than medium temperature groups, which in turn weighed significantly more than low temperature groups. In addition, the F2 progenies of low temperature exposed F1 sires had significantly greater length and weight than F2 progenies sired by high temperature exposed F1 sires, regardless of the progeny’s own temperature exposure treatment. These results suggest a possible negative epigenetic effect of high temperature exposure during the larval stages of F1 males that results in lower growth performance of subsequent progeny, regardless of the progeny’s rearing temperature. There was also some significant interaction effects of progeny and sire temperature treatment on weight and length, but they were not consistently significant along the experimental period.
The significant difference in growth resulting from early high temperature exposure during the larval and early juvenile stages continued throughout the juvenile stage and into adulthood of both F1 and F2 fish, despite transition to rearing all groups at the same ambient temperatures. These results suggest that the temperature experienced at early life stages affects the growth of future life stages of an individual as well. Sex ratio results are to be collected from the F2 progenies at the end of 2021 and will be presented along with growth and survival of F2 progenies during the second year of grow-out. This study provides the first evidence of a masculinization effect of high temperature in Yellow perch exposed during the larval stages.