Rapid identification of scallop gender and gonadal maturity using endoscopy

Scallops are important cultured bivalve in China. Before the artificial reproduction of scallops, it is imperative to segregate male and female parents, and monitor gonadal development to determine the optimal timing for seedling production. Currently, scallop gender and gonad maturity are determined in vivo through stimulating the soft tissues with nylon rope stimulation or dry in shade to let the scallops open their shell, and then observing the color of the gonads. The aforementioned methods are time-consuming and conducted off-water, potentially leading to the miscarriage of parent scallops and the seedling production being out of control. In this research, a novel approach utilizing endoscopy was employed to identify gender and gonadal maturity of scallops, based on the coloration in gonadal images captured via a probe inserted through the byssus orifice between their shells. Our data indicated that scallop gonads' color and gender could be clearly visualized with endoscope without direct contact with the delicate soft tissues while the scallops were in a closed state, and the time required was 1/2 and 1/4 of that using traditional nylon rope stimulation and dry in shade, respectively. Furthermore, the endoscope could capture clear images of scallop gonads in seawater, facilitating in-situ observation of scallop gonads. This non-invasive endoscopic technique eliminates the need to stimulate scallop opening the shells, allowing for accurate and rapid gonads observation and gender identification, thereby enhancing the efficiency of scallop breeding.