Risk of eutrophication due to increased nutrient load in the waters adjacent to the cage fish farm

The possibility of algal blooms at the location of the cages and the surrounding water is one of the major risks associated with the management of fish farming in cages. In the present study, the risk of eutrophication (risk of algal blooms), the rate of nutrient enrichment (eutrophication) and the availability of nutrients (for phytoplankton consumption) due to fish farming in the waters adjacent to the cages with Farther from the location of the cages during a six-month rearing period in Qeshm region was compared. In the study, the range of changes related to scale and non-scale trophic indices and trophy efficiency coefficients were equal to 3.75-5.23, 3-4-78 and 3.78-4, respectively. Based on the studied indicators, the trophy status in the waters adjacent to the cages is high (at the mesotrophic level) and the risk of blooming is high, as well as the availability of nutrients by primary producers (phytoplankton) based on the trophy efficiency coefficient was high. However, in the waters farther from the location of the shelves (control station), the trophy status was moderate (at the mesotrophic level) and the risk of blooming and the availability of nutrients were low. The use of superior technologies and proper, principled and scientific management of water and food quality, in addition to reducing the environmental effects of such activities can play an important role in increasing production, exports and further valuation by this industry.