Post-spawning bath treatments to reduce morbidity and mortality of pond-cultured pikeperch (Sander lucioperca L.) broodstock

摘要

High mortality (88.9-91.4%) of pond-cultured pikeperch Sander lucioperca broodstock was found 10days post-spawning primarily due to body injury (15.2-18.2% of body area) and secondary fungal infection (27.6-34.8% of body area). Ninety days post-spawning mortality was 97.1-98.1%. Surviving broodstock showed satisfactory condition with no observable pathology. Thirty-six treatments were evaluated for effects on post-spawning injury, fungal infection, and broodstock mortality: salt short (60-240min) and long baths (36-144h) at concentrations of 5-20gL(-1) and 2.5-10gL(-1), respectively, and formalin short (15-60min) and long baths (24-72h) at 0.15-0.30mlL(-1) and 0.015-0.030mlL(-1), respectively. The treatments most effective in reducing post-spawning pathology and mortality were salt baths for 144h at 2.5, 5, and 10gL(-1) and formalin at 0.015mlL(-1) for 48h. These treatments were evaluated in the following trial, and their positive effect was confirmed by low mortality of broodstock (0-8.3%) and low (3.0-10.5%) injury at 10days post-spawning and no additional mortality or body injury at 90days post-spawning. No secondary fungal infection was observed at either time post-spawning. The three salt baths are recommended as effective treatments for reduction of post-spawning morbidity and mortality of pond-cultured pikeperch broodstock.