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

Abstract

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.

Gametogenesis and Assessment of Nonlethal Tools to Assign Sex and Reproductive Condition in Burbot

“…Ultrasound has been used to assign reproductive condition in other female teleosts, such as steelhead and Channel Catfish, by detecting ovarian follicles (Evans et al. ; Novelo and Tiersch ). Compared to the ovarian follicles we observed in ripe female Burbot, ovarian follicles in ripe female steelhead are much larger (3 mm in diameter), allowing them to be easily delineated using ultrasound (Evans et al.…”

“…Ultrasound has also been used to assign reproductive condition by detecting visual changes in developing gonads (e.g., appearance of oocytes, changes in tissue echogenicity, and differences in gonad size; Evans et al. ; Novelo and Tiersch ). In female steelhead (anadromous Rainbow Trout), ultrasound was used to detect morphological differences between prespawn and postspawn ovaries (Evans et al.…”

“…For example, sex can be assigned with 100% accuracy in Pacific Halibut because the ovaries are rounded and tapered, whereas the testes are sickle-shaped and pointed (Loher and Stephens 2011). Ultrasound has also been used to assign reproductive condition by detecting visual changes in developing gonads (e.g., appearance of oocytes, changes in tissue echogenicity, and differences in gonad size; Evans et al 2004;Novelo and Tiersch 2016). In female steelhead (anadromous Rainbow Trout), ultrasound was used to detect morphological differences between prespawn and postspawn ovaries (Evans et al 2004).…”

“…Prespawn testes had a mean area of 2.86 cm 2 , whereas postspawn testes had a mean area of 0.62 cm 2 (Evans et al 2004). An ultrasound index of gonadal development in female Channel Catfish Ictalurus punctatus was also described using morphological and echogenic changes in ovaries during development (Novelo and Tiersch 2016). Undeveloped (i.e., nonreproductive) ovaries were differentiated by homogeneous echogenic texture and a lack of distinct oocyte structures, whereas developing (i.e., reproductive) ovaries had distinct oocyte structures (Novelo and Tiersch 2016).…”

Artificial fertilization and generating families for a selective breeding programme of large yellow croaker (Larimichthys crocea)

“…In trial 2, the latency time was determined by observing courtship behaviour and less spawning difficulties occurred. More non-invasive methods should thus be tested for measuring the stages of reproductive maturation in the stress-sensitive fish, such as measurement of sex steroid hormones in surface mucus and use of ultrasound imaging for monitoring gonadal development (Schulz et al 2005;Novelo and Tiersch 2016).…”