Effects of lighting spectrum and disturbance level on the growth and stress responses of yellow perch Perca flavescens

.— We evaluated the effects of different lighting spectra and routine disturbances on the growth and stress responses of yellow perch Perca, flavescens. Fish were reared in tanks under one of three different lighting spectra: blue (405–530 nm), red (600–750 nm). or full spectrum (380–750 nm). For each lighting spectrum, fish were reared under one of two disturbance levels: one in which the fish were exposed to 2–4 daily routine disturbances which typify intensive tank culture conditions (e.g., casting shadows over the tank, sham tank siphoning, and dissolved oxygen measurement: ‘disturbed’). or a second treatment in which such disturbances were minimized (‘undisturbed’). The fish were reared for 87 d under temperature, photoperiod. and feeding conditions near optimal for the growth of yellow perch. The cortisol stress response of the different fish groups was evaluated by measuring baseline serum cortisol levels on days 0, 1,3, and 21, and by measuring cortisol levels 30 min after the application of an acute handling stressor on days 0, 1, and 3. Treatment effects on growth were measured from days 21–86 of the study. On day 87, various organs and parameters were evaluated to compare the health and condition of fish reared under the different treatments. Disturbed fish gained less weight and length, and had a significantly lower condition factor than undisturbed fish. Additionally, the disturbed fish showed no signs of acclimation to the frequent disturbances. The fish under red and full spectrum light gained more length than those under blue light. Frequent disturbance had a greater negative effect on length gain in fish reared under red light than in those reared under the other light treatments. On day 21, but not on other days, baseline cortisol levels were higher in disturbed than in undisturbed fish. Undisturbed fish had higher levels of mesentery fat than disturbed fish. Our results demonstrate that yellow perch growth can be significantly affected by disturbance level and lighting conditions. These factors should be taken into consideration when developing culture strategies to maximize the growth of yellow perch reared under intensive culture conditions.