THE UPTAKE, DISTRIBUTION AND METABOLISM OF BENZO[A]PYRENE IN COHO SALMON (ONCORHYNCHUS-KISUTCH) DURING THE PARR-SMOLT TRANSFORMATION

Benzo[a]pyrene (BaP) uptake, distribution, and metabolism patterns wer e investigated from February to June during the transformation of fres hwater coho salmon (Oncorhynchus kisutch) parr to smolts. At a BaP con centration of 5 mu g/L, uptake rates increased significantly from 0.01 +/- 0.000 mu g/g/h in February to 0.04 +/- 0.003 mu g/g/h in May and declined to 0.035 +/- 0.004 mu g/g/h in June. Following a 24-h exposur e to BaP, the highest percent of body burden of BaP was found in the l iver, gills, skin, and bile. The proportion of BaP in the liver and gi lls increased in fish from February to May and declined in June, where as the proportion of BaP in the bile continued to rise until June when it reached a maximum of 49% of the body burden. The percent body burd en of BaP in tissues such as the stomach, intestine, visceral fat, mus cle, and brain did not show significant changes through the duration o f the study. An analysis of bile suggests that both coho salmon parr a nd smolts are capable of metabolizing BaP via phase I and II biotransf ormation reactions to glucuronide, sulfate, and other conjugated metab olites. No significant changes occurred in the proportions of metaboli te classes during the parr-smolt transformation process.