Development and Evaluation of an Ultrasound Imaging Reproductive Index Based on the Ovarian Cycle of Channel Catfish, Ictalurus punctatus.

Commercial production of hybrid catfish (female channel catfish Ictalurus punctatus × male blue catfish Ictalurus furcatus) is reliant on interdependent biological, environmental, and technical procedures. This study addresses one of these critical components - the evaluation of channel catfish ovarian development based on sonographic analysis. The objectives were to: (1) develop a channel catfish ovarian ultrasonography index, (2) test the effect of the spawning trials on fertilization estimates of fish assessed using the ultrasonography index, and (3) evaluate the expected (hypothesized) and observed outcome of the ultrasonography assessments. Seven ovarian morphology classifications were developed based on ultrasonography of 915 channel catfish ( N = 915 images), and 210 females were selected for spawning. The predictions based on the classifications prior to hormone injection showed a significant effect ( P < 0.002) on the observed outcomes (viable or nonviable eggs). The probability of correct classification was 0.86-0.89 for Categories 3 (developing), 4 (advanced), and 5 (mature), and 0.93-1.0 for Categories 1 (undeveloped), 2 (underdeveloped), 6 (spawned), and 7 (atretic). The ultrasonography index covered the full range of ovarian dynamics (i.e., recrudescence through spawning). It provided an unobtrusive, direct method of ovarian assessment to work toward improving the efficiency of broodstock selection. [ABSTRACT FROM AUTHOR]