 When comparing adjacent populations of white sucker fish, the exposed female fish can have up to five oocyte stages and asynchronously developing ovaries versus the unexposed female fish who usually have two oocyte stages and group-synchronously developing ovaries.Previously, this type of difference has only been found between tropical and temperate species.Sperm concentrations and motility perimeters are reduced in male fish exposed to xenoestrogens in addition to disrupt stages of spermatogenesis.