The enhancing effect of spawning on elimination of a persistent polychlorinated biphenyl from female yellow perch.

Distribution and elimination of 2,5,2',5'-tetrachloro[14C]biphenyl (4-CB) were studied for 6 months after exposing sexually mature female yellow perch to the compound in water and transferring them to flowing 4-CB-free water. Perch that were exposed in January spawned in May, and the study was terminated in June. During the first 41/2 months after exposure, the t1/2 for whole-body elimination was 22 weeks, primarily by elimination of 4-CB from the viscera and carcass. During spawning, enhanced elimination (t1/2 less than 0.7 weeks) was due to the voiding of eggs containing 4-CB. After spawning, whole-body elimination returned to a slower rate (t1/2 = 16.3 weeks). Prior to the enhancement in 4-CB elimination rate during spawning, there was a redistribution of 4-CB residues within the body of the perch which was characterized by a transfer of 4-CB residues from primarily the carcass and viscera to eggs. Two weeks after exposure, 30% of the initial 4-CB body burden was distributed to the eggs, whereas just prior to spawning, about 50% was present in this tissue. These findings demonstrate that egg maturation and spawning result in a significant reduction in the body burden of a persistent polychlorinated biphenyl in a lean-fish species.