Photo credit: AKVA Group
Review: Abdel Rahman El Gamal (Founder of the website)
The Underwater lighting when practiced in a given aquaculture operation is often adapted for fast growing species such as salmon, trout, cod and others. In fact, the use of submerged artificial lighting during-night hours is steadily gaining more interests in application.
The purposes of submerged lighting although vary; better productive performance and easier management are the main ones.
When used in salmon farms, the underwater lightening is believed to enhance farm productivity through slowing down the maturation process and reducing the risk of early maturation prior to harvest for the exposed salmon enabling them to grow to larger sizes before sexual maturation. There are reports/observations about these findings for the Atlantic salmon (Salmo salar) and King salmon (Oncorhynchus tshawytscha).
The optimum underwater lightening results in an even light distribution which in turn assists in developing almost uniform densities of fish in culture units and so, improves the utilization of feed especially in farming units with high fish density and high turbidity water.
There are some environmental impacts which may accompany the submerged lightening including –in case of cages- a possible aggregation of aquatic organisms (e.g. zooplankton, bait fish) living in open waters around the illuminated areas of the cages increasing their vulnerability to possible levels of night-time predation.
In regard to birds, the attraction of birds to the artificial lighting over the farming units will depend on the behavior of birds especially the nocturnal birds which are active during nights. The attraction of these birds to lighted areas increases their risk of their collision and/or entanglement with farm structures.