Field trial evaluation of povidone iodine as an effective disinfectant for different stages of returning spawners salmon

Reaching with the fertilized gametes to the production stage is a critical process for the success of aquaculture and restoration of wild fish programs worldwide. Iodophors are routinely used to disinfect both broodstocks and fertilized eggs to control vertical as well as horizontal transmission of fish pathogens. During three successive spawning cycles, the specific fish pathogens Aeromonas salmonicida and Renibacterium salmoninarum associated with typical clinical picture have been isolated from examined salmon before gamete collection. The prevalence approximately reached 51% and 79% for A. salmonicida and R. salmoninarum respectively. On the other hand, the R. salmoninarum was isolated from the collected eggs of the broadstocks used for spawning in the above mentioned cycles. Average prevalence of infection in tested eggs was 15%. At the pre-rinsing cycles, the bacterial load was determined as 1.2 × 10 and 0.6 × 10 CFU/plate for A. salmonicida and R. salmoninarum in spawners respectively. On the level of fertilized eggs, the load was determined as 0.2 × 103 CFU/plate and 0.1 × 103 for A. salmonicida and R. salmoninarum respectively. In the following spawning cycle, the efficacy of povidone iodine as surface disinfectant for returning spawners and fertilized eggs of Chinook salmon were tested. Concentrations of 60 mg/L povidone iodine for 30 minutes as initial dose followed by a maintenance dose of 70 mg/L for 10 minutes were applied as rinsing solutions for ♂ and ♀ Chinook salmon spawners. Eggs were shell-hardened in 80 mg /L povidone iodine for 30 minutes. Isolation trials from equal number of post rinsing spawner Chinook salmon and fertilized eggs indicated a sharp decline in bacterial colonies number per plate for spawners and eggs. The achieved post-rinsing results are highly indicative for the efficacy of povidone iodine as efficient disinfectant for both fish and eggs. Ultimately, the current study will ensure the production of fish populations with less bacterial load and consequent potent health status. [Life Science Journal. 2007; 4(3): 87 – 93 ] (ISSN: 1097 – 8135).