Constant long photoperiod inhibits the onset of the reproductive cycle in roach females and males

Abstract

Photoperiod and temperature are commonly accepted as the determinant factors for the control of the reproductive cycle in freshwater fishes. However, this determining effect is dependent on fish species. While applying a constant long photoperiod has an inhibitory effect in some species, the same photoperiodic manipulation has a stimulating effect in others. In cyprinids, a decrease in temperature or photoperiod can induce the gonad recrudescence. However, in roach Rutilus rutilus an early spring spawner cyprinid, there is little knowledge about the cueing role of each environmental factor. The aim of this work was to study the effect of a constant long photoperiod on the gametogenesis in roach. Fish were kept under either naturally simulated photoperiod or artificial constant long photoperiod and sampled at three times: at the beginning of photoperiod decrease, at the beginning of temperature decrease, and at the end of temperature decrease. Morphological parameters (gonado-somatic, hepato-somatic and viscera-somatic indexes), plasma sexual steroids, and proportion of gametogenesis stages were estimated at each sampling time. The results showed that a constant, long photoperiod exerted inhibitory effects on gametogenesis advancement in both females and males that could stem from decrease of sex steroid production. Roach displayed a similar response to photoperiodic manipulations to other early spring spawners like percids, such as European perch, yellow perch and pikeperch. These results clearly showed the cueing role of the photoperiod in the induction of the reproductive cycle in roach.

Reproductive cycle of the female Anisotremus scapularis (Tschudi, 1846) on the marine coast of Callao, basic knowledge to go towards its aquaculture

“…Total fish weight (g) Â 100 (Ben Ammar et al, 2020) To deepen the analysis of biometric indexes, it was created a new ordinal variable called "length categories"; using standard length data recorded. This new variable grouped the specimens into two categories of standard length: The first category included the collected specimens with lengths greater than or equal to 30 cm (≥ 30 cm individuals), and the second category included the collected specimens with lengths smaller than 30 cm (< 30 cm individuals).…”

Effects of different photoperiods on growth and ovarian development and maturation of silver pomfret Pampus argenteus

“…In teleosts, gonadal development and maturation are affected by environmental and seasonal changes, such as temperature, light, nutrition and hormones (Abdollahpour et al ., 2018; Boeuf & Falcon, 2001; Shahjahan et al ., 2013; Siegfried, 2010). Among them, photoperiod is an important environmental factor that regulates the reproductive cycle of fishes (Ben Ammar et al ., 2020; Bromage et al ., 2001). Photoperiod refers to the ratio of the length of day to that of night every day (24 h).…”