The Effect of Non-Circadian Photoperiod on Growth and Puberty Onset of Brook Trout Salvelinus fontinalis Mitchill

Abstract

The aim of the present study was to assess the effects of a prolonged photoperiod on growth rate and sexual maturation in brook trout Salvelinus fontinalis. The task of the experiment was to determine the most effective light regimen capable to minimizing the effects of puberty, including impairment of somatic growth and further general characteristics. In this regard, the studied fish were reared under three photoperiod regimens in which fish were exposed to 24 h continuous light alternating with 24 or 48 h under the ambient photoperiod or 48 h continuous light alternating with a 24 h ambient photoperiod. A control group was reared under the natural ambient photoperiod. Four-hundred and fifty fish with an average initial body weight of 101.3 ± 1.2 g were used for each experimental group (three replicates of each treatment plus control). A statistically lower growth rate showed control groups in both sexes. At the end of the study, control males had an average body weight of 226.6 ± 39.8 g and control females a body weight of 199.8 ± 12.2 g. At the same period, a significantly higher average body weight was found in groups reared 24 h under ambient photoperiod alternating with a 48 h continuous light regime (2CP:1AP) in both sexes (296.56 ± 62.5 g—males, and 239.9 ± 19.2 g—females, respectively). A significantly higher percentage of sexually mature fish was observed in the control group (80% of males and 29% of females, respectively). We found significantly fewer sexually mature females compared to males. The lowest survival was observed in group 2CP:1AP at 92%. It was concluded that regimen under which fish was exposed to 48 h of natural ambient photoperiod alternating with 24 h of constant light (1CP:2AP) lead to the successful delay of gonad development and onset of puberty and increased somatic growth in both sexes.

Status assessment and opportunities for improving fish welfare in animal experimental research according to the 3R-Guidelines

“…For brook trout (Salvelinus fontinalis), it could be shown that a more natural light regime seems to be more suitable. Lundova et al exposed specimen to 48 h of natural photoperiod alternating with 24 h of constant light, which resulted in increased somatic growth in both sexes (Lundova et al 2021). Another positive effect was the delayed gonadal development and the onset of puberty (Lundova et al 2021).…”

“…Lundova et al exposed specimen to 48 h of natural photoperiod alternating with 24 h of constant light, which resulted in increased somatic growth in both sexes (Lundova et al 2021). Another positive effect was the delayed gonadal development and the onset of puberty (Lundova et al 2021). Additionally, Valenzuela et al concluded in their study that a 24/0 regime contributes to increased stress production in rainbow trout (Valenzuela et al 2022).…”

Impact Analysis of Photoperiodic Disorder on the Eyestalk of Chinese Mitten Crab (Eriocheir sinensis) through High-Throughput Sequencing Technology

“…The photoperiod serves as a key cue for animals to modulate their life activities. Fish growth and gonadal development are influenced by the photoperiod, with long-day manipulation applied for healthy growth and early gonadal maturation in ornamental fish [6,7]. Crustaceans, such as crayfish, are susceptible to light signals that affect molting frequency, growth, and reproductive efficiency [8,9].…”