Effects of pulp and paper mill effluents on the reproductive and physiological status of perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) during the spawning period.

Reproductive and physiological parameters were studied during the spawning period in perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) downstream of two pulp and paper mills and reference sites in southern Lake Saimaa, Finland. Plasma 17β-estradiol (E2) and testosterone (T) concentrations in female perch and roach decreased during the spawning period. At one of the mill sites, plasma E2 and T concentrations in pre-spawn female and male perch and male roach were significantly higher. As compared with the reference sites, liver ethoxyresorufin O-deethylase (EROD) activity in exposed perch and male roach was 29%–91% higher, and for exposed female roach it was 53%–79% lower. In contrary to perch, EROD activity in male roach was higher than in females. Resin acids concentration in the bile of exposed fish (0.2–2.0 μg ml) was higher than at the reference sites, whereas chlorophenolics concentration was similar (0.4–0.7 μg ml). Results indicate that exposure to pulp and paper mill compounds still exists, although much lower than before implementation of ECF bleaching and activated sludge wastewater treatment at the mills. Effects of pulp and paper mill effluent on reproduction of spawning fish were inconclusive.