Abstract
Jackfish Bay is an isolated bay on the north shore of Lake Superior, Canada that has received effluent from a large bleached-kraft pulp mill since the 1940s. Studies conducted in the late 1980s found evidence of reductions in sex steroid hormone levels in multiple fish species living in the Bay, and increased growth, condition and relative liver weights, with a reduction in internal fat storage, reduced gonadal sizes, delayed sexual maturation, and altered levels of circulating sex steroid hormones in white sucker (Catostomus commersonii). These early studies provided some of the first pieces of evidence of endocrine disruption in wild animals. Studies on white sucker have continued at Jackfish Bay, monitoring fish health after the installation of secondary waste treatment (1989), changes in the pulp bleaching process (1990s), during facility maintenance shutdowns and during a series of facility closures associated with changing ownership (2000s), and were carried through to 2019 resulting in a 30-year study of fish health impacts, endocrine disruption, chemical exposure, and ecosystem recovery. The objective of the present study was to summarize and understand more than 75 physiological, endocrine, chemical and whole organism endpoints that have been studied providing important context for the complexity of endocrine responses, species differences, and challenges with extrapolation. Differences in body size, liver size, gonad size and condition persist, although changes in liver and gonad indices are much smaller than in the early years. Population modeling of the initial reproductive alterations predicted a 30% reduction in the population size, however with improvements over the last couple of decades those population impacts improved considerably. Reflection on these 30 years of detailed studies, on environmental conditions, physiological, and whole organism endpoints, gives insight into the complexity of endocrine responses to environmental change and mitigation.
Highlights
Jackfish Bay is an isolated bay on the north shore of Lake Superior, Canada, and it has received the effluent from a large bleached-kraft pulp mill at Terrace Bay, Ontario since the 1940s
During the baseline years of primary treatment (1988 and 1989), both female and male white sucker sampled from Jackfish Bay during the spring were older, shorter, and had higher condition factors than white sucker from Mountain Bay (Tables 3, 4 and Figure 3)
In fall 1988, female and male fish sampled from Jackfish Bay were shorter, weighed less, and had higher condition factors, with older females and younger males found at the exposed site (Tables 5, 6 and Figure 5)
Summary
Jackfish Bay is an isolated bay on the north shore of Lake Superior, Canada, and it has received the effluent from a large bleached-kraft pulp mill at Terrace Bay, Ontario since the 1940s. In the late 1980s studies on the effects of pulp mill effluent entering Lake Superior at Jackfish Bay documented delayed sexual maturity, reductions in gonad size, sex steroid hormones and secondary sex characteristics in white sucker (Catostomus commersonii; 1, 2). Studies confirmed a delay in sexual maturity in lake whitefish (Coregonus clupeaformis) at Jackfish Bay (3), and reproductive impacts in white sucker at a number of other mills (4). Modeling of the reproductive changes documented during the late 1980s and early 1990s at Jackfish Bay suggested a 34% to 51% annual decrease in recruitment of white sucker (8) These studies confirmed earlier studies in Sweden which suggested that pulp mill effluents releasing organically bound chlorine and its chemical constituents could cause impacts on the growth and reproduction of fish at much lower environmental concentrations than previously thought (9). Studies at Jackfish Bay, Ontario, Canada, and those done at Norrsundet in Sweden, increased global awareness of the potential for industrial effluents to impact reproductive processes in fish, and prompted studies in more than 15 countries (11)
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