Non‐lethal assessment of reproductive stage for female blue sharks <i>Prionace glauca</i> using sex steroid hormones

Abstract

Abstract Plasma concentrations of progesterone (P 4 ) and 17β‐oestradiol (E 2 ) in juvenile, pre‐ovulatory, early, mid‐ or late pregnancy stages of female blue sharks Prionace glauca were analysed. Concentrations of P 4 were significantly higher in pregnant than in non‐pregnant individuals, whereas E 2 concentrations increased with embryonic and follicular development. A highly accurate (86.1%) random forest classification model was developed to predict shark pregnancy. It is proposed that hormone concentrations could be used for the subsequent non‐lethal determination of female P. glauca reproductive state.

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