Is the birth control pill an effective form of reproduction for wild fish?
Karen Kidd, University of New Brunswick
Considerable evidence exists that reproduction in freshwater fish is being compromised by compounds present in municipal wastewater discharges (e.g. Blazer et al., 2007; Hinck et al., 2009; Jobling et al., 1998; Jobling and Tyler, 2003; Sumpter and Johnson, 2008). Fish exposed to these substances are unable to develop eggs or sperm, or spawn successfully (see review by Scholz and Kluver, 2009). One group of contaminants of particular interest are the estrogens and estrogen mimics, as they can feminize male fish and decrease their reproductive performance at very low water levels. Feminized male fish produce egg yolk proteins and, in the more severe cases, develop eggs (Jobling et al., 1998), are found downstream of municipal wastewater discharges, and are more common in heavily populated catchments (Jobling et al., 1998; Blazer et al., 2007; Desforges et al., 2010). These wastewaters contain numerous potent estrogen mimics but the ones of greatest concern are the natural (e.g. estradiol) and synthetic (e.g. ethynylestradiol from the birth control pill) estrogens women excrete (Desbrow et al., 1998; Sumpter and Johnson, 2008). Although treatment can remove estrogens from the effluents (e.g. Kirk et al., 2002; Bringolf et al., 2003), several rivers in North America contain feminized male fish and lab studies have confirmed that the release of estrogens can explain most of the impacts in wild fish living downstream (e.g. Länge et al., 2001; Parrott et al., 2005). Despite the overt evidence that fish are being adversely impacted by estrogens, it is not understood whether there are fewer fish in the rivers because of estrogen inputs. It has been recognized nationally and internationally that there is a need to determine to better understand whether these hormones and mimics are interfering with the sustainability of fish populations. This presentation will describe a multi-year, whole lake experiment to address this research need.