Gonad Size Measured by Ultrasound to Assign Stage of Maturity in Burbot

Abstract We measured gonad size (diameter and circumference) by ultrasound used it as a metric to assign stage of maturity in Burbot Lota lota from Lake Roosevelt, Washington. collected paired tissue measurements monthly November 2017 March 2018 processed for histological analysis confirm maturity. diameter circumference ultrasound. also excised (i.e., true diameter) digital calipers measuring tape. All late vitellogenic (stage 6) ovaries had greater than 3.90 cm, suggesting value cm or may be characterize females capable spawning the current reproductive cycle. One mid-spermatogenic 3) all ripe 4) testes were too large assigned 5.11 maximum being our transducer. A males Testis is not reported because some wider transducer could measured. Measurements testis did differ between measurement methods (ultrasound versus true), but ovary higher measurements. attributed difference flattening while applying Gonad highly correlated with gonadosomatic index ovarian follicle diameter, indicating an appropriate development Burbot.