I attended a meeting in Alaska where several Phd. types were talking about chemical polloution altering fecundity in fish stocks. One of them cited a study that showed Rainbow trout could be rendered sterile by as little as .0063 parts per Quadrillion of Dioxin in water. No mention was made of growth hormone in effluent from feed lots but hey they were focused on Pulp Mill effluent.
This beggs the question what is the effect of growth hormones in aqua culture where the stuff is put deliberately into the water, not just "effluent" discharge?