This AOP details the linkage between binding and activation of androgen receptor (AR) in
females and reductions in cumulative fecundity and spawning. AR-mediated activities are
among the major concerns in endocrine disruptor screening programs. Cumulative
fecundity is the apical endpoint considered in the OECD 229 Fish Short Term Reproduction
Assay. It is also one of several variables with demographic significance in forecasting fish
population trends. Therefore, this AOP supports the use of measures of AR activation as a
means to identify chemicals with potential to adversely affect fish populations. At present,
this AOP is largely supported by evidence from small laboratory model fish species. While
many aspects of the biology underlying this AOP are largely conserved across oviparous
vertebrates, its relevance to vertebrate classes other than fish, or to fish species employing
different reproductive strategies has not been established. Thus, the applicability domain
should be carefully considered when evaluating fit-for-purpose.