However, the synthesis of the Vtg protein can occur in males when exposed to exogenous estrogens and has been linked to environmental estrogenic endocrine disruption in fishes.
Laboratory and field research suggests that reproductive health and viability is compromised due to these disruptions and it is therefore of highest interest to understand natural trends of Vtg within healthy populations of declining species.
Sex steroid hormones typically undergo seasonal increases associated with reproductive activity.
In other turtle species, male plasma total testosterone (TT) increases in the fall/winter associated with spermatogenesis, and some species exhibit a second TT increase in the spring when mating and courtship behavior peaks.