Evaluation of physiological and molecular tools to assess ovarian stages in the black tiger prawn ( P enaeus monodon )

Advancing knowledge of the molecular mechanisms governing vitellogenesis and spawning in the black tiger prawn, Penaeus monodon , requires an efficient method for identifying ovarian stages. Several physiological and molecular tools have been employed to define these stages in laboratory studies. However, it is necessary to assess these tools collectively to develop comprehensive staging approaches for studies aimed towards sustainable broodstock management. This study evaluated gonadosomatic and hepatosomatic indices (GSI and HSI), hemolymph Brix index, hemolymph 20‐hydroxyecdysone (20HE), and hemolymph vitellogenin (Vg) levels in eyestalk‐ablated P. monodon broodstock at defined ovarian stages. Ovarian stages were classified by ovarian histology and oocyte diameter measurements. Circulating Vg concentrations were measured by a newly developed enzyme‐linked immunosorbent assay (ELISA). The results demonstrated that GSI correlated negatively with HSI; the hemolymph Brix index significantly increased from the previtellogenic to the late vitellogenic stage; and hemolymph 20HE levels declined as the ovaries matured. Vg rose sharply in early vitellogenesis and remained elevated throughout ovarian development. The Vg ELISA was highly specific, sensitive, and reliable, enabling the detection of the Vg molecule and its fragments in hemolymph samples. Consequently, the hemolymph Brix index, 20HE, and Vg ELISA can be used as non‐lethal tools to investigate physiological and biochemical changes in hemolymph during ovarian maturation in P. monodon . This comprehensive approach would support studies aimed at assessing alternative methods of eyestalk ablation, as well as research evaluating the effects of diet, environmental manipulation, and genetic selection, among others.