Polychlorinated biphenyl exposure and fish recruitment from 1988 to 2002 in the upper Hudson River, New York, USA

Starting in the late 1940s, fish in the upper Hudson River, New York, USA, were exposed to polychlorinated biphenyls (PCBs) from discharges from two manufacturing plants. These discharges greatly decreased in 1976, and PCB concentrations in fish generally declined between 1980 and 1991, increased in 1992-1994 due to a failure in 1991 of a structure that contained PCBs, and then decreased after 1994. To assess the impact of PCBs on fish reproductive success and recruitment, we collected yellow perch (Perca flavescens), largemouth bass (Micropterus salmoides), and brown bullhead (Ameiurus nebulosus) from 2002 to 2006 at two sites just downstream of these PCB sources. A subsample of these fish were aged; ages of remaining fish were assigned using a length:age key, and linear catch curves [loge (Number-at-age) = age] were computed. Maximum ages ranged from 11 to 16 years across species, and residual values generated from these catch-curve regressions represented relative year-class abundances produced from the late 1980s to the early 2000s. Wet-weight muscle tissue PCB concentrations in adults varied from average highs of 18-30 μg/g in the late 1980s-mid 1990s to lows of 3-9 μg/g by 2002 at the site nearest to the PCB sources. PCB concentrations in adult fish were unrelated to the formation of weak or strong year-classes in all three fish species. Although PCB concentrations were 2 to 8 times higher at the site nearest the PCB sources compared to a downstream site, natural mortality rates (fish harvest prohibited) derived from catch-curves were similar between sites for all three species. Thus, longevity and production of older year classes were consistent between sites. For these three species, we did not detect any PCB-mediated effect on fish recruitment at the population level at adult PCB concentrations (18-30 μg/g).