Influences of photoperiod on growth and reproduction of farmed fishes - prospects in aquaculture

Abstract

Photoperiodism is a critical environmental factor that influences the development, growth, feeding, metabolism, and reproduction in all living organisms. Photoperiod regulates the biological rhythms which entrain the circadian clock in association with the sleep-wake cycle, feed intake, metabolism, cognition and hormone secretion which are essential for physiological homeostasis in fishes. This study summarizes the effect of photomanipulations on early life-history characteristics, growth, reproductive performance and stress response in farmed fishes. Studies found that photomanipulations for long-day period results in improved growth in larvae, juveniles and adults in some fish species. Long-day photoperiod also has a positive effect on the reproductive performance in fishes depending on the species, photoperiod and exposure time. In contrast, short-day photoperiod has both positive and negative effects on growth and reproduction in farmed fish species. In both cases (short-day and long-day photoperiod conditions), manipulated photoperiod exerts a stress response by altering the hematobiochemical profile of fishes. A number of biomolecules including melatonin, hypothalamic neuropeptides, growth factors and sex steroids are involved in regulation of growth and reproduction in changing photoperiod depending on the species. Overall, this study is the first comprehensive review regarding photomanipulations and aquaculture performance of commercially important farmed fishes all over the world.

Keywords

• Photomanipulations
• Light-dark
• Biological rhythms
• Hematobiochemical parameters
• Stress response