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

Abstract

High mortality (88.9–91.4%) of pond-cultured pikeperch Sander lucioperca broodstock was found 10 days 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 (60–240 min) and long baths (36–144 h) at concentrations of 5–20 g L−1 and 2.5–10 g L−1, respectively, and formalin short (15–60 min) and long baths (24–72 h) at 0.15–0.30 ml L−1 and 0.015–0.030 ml L−1, respectively. The treatments most effective in reducing post-spawning pathology and mortality were salt baths for 144 h at 2.5, 5, and 10 g L−1 and formalin at 0.015 ml L−1 for 48 h. 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 10 days post-spawning and no additional mortality or body injury at 90 days 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.