Assessing Reproductive Condition in Captive and Wild Common Snook Stocks: A Comparison between the Wet Mount Technique and Histological Preparations

Abstract

We describe oocyte development in Common Snook Centropomus undecimalis and, secondarily, present results from a comparison of the wet mount technique with histological preparations of ovarian biopsies. Potential differences in ovarian development between wild and captive broodstock were investigated. Results showed that mean oocyte diameter (µm) was not statistically different between the two groups or within each defined stage and step of reproductive condition. Histological preparations were used to validate the wet mount technique as a rapid, yet accurate, low-cost alternative for assessing reproductive condition in Common Snook. When compared with histology, the wet mount provided a precise method for determining whether female broodstock were candidates for hormone induction in aquaculture applications. However, due to the loss of fine resolution, it was not possible to identify cortical alveoli, oocyte atresia, and postovulatory follicle complexes by using the wet mount technique. Despite these limitations, findings from this study indicate that the wet mount technique may have applications in fishery biology as a noninvasive method for assessing reproductive condition in wild fish stocks.A critical component for many studies of fish reproductive biology is an accurate assessment of the reproductive condition of individual fish. There are numerous macroscopic and microscopic methods for evaluating the gonadal condition of fish, particularly with regard to ovarian development. West (1990) reviewed some of these in detail and discussed the level of accuracy and usefulness for each. The methods in use range from

Development and fate of the postovulatory follicle complex, postovulatory follicle, and observations on folliculogenesis and oocyte atresia in ovulated common snook,Centropomus undecimalis(Bloch, 1792)

“…Pieces of ovarian lamellae were sucked into the tubing and subsequently blown onto a glass microscope slide and evaluated in real time using the wet mount technique (Neidig, Skapura, Grier, & Dennis, ). The technique has been improved and uses updated oocyte staging terminology (Rhody, Neidig, Grier, Main, & Migaud, ), patterned after “Adaptable Oocyte Staging,” a term that was introduced by Grier () following the introduction of mitosis and meiosis‐based oocyte staging (Grier et al, ). The wet mount technique renders basophilic, primary growth oocytes as clear and with well‐defined nucleoli, but cortical alveoli are not resolved.…”

“…The six stages are subdivided into “steps.” To adapt the staging to particular species of fish or to systematic groups of fish, it is only necessary to alter the steps. This is also the only oocyte‐staging scheme (Grier et al, ; Neidig et al, ; Rhody et al ) that is based on the universality of cell division, mitosis and meiosis.…”

Fish Oocyte Ageing and its Effect on Egg Quality

“…Under cultured conditions, hormone treatments can significantly induce ovulation and synchronize ovulation, facilitating hatchery management. A simple coverslip wet-mount method has been developed for rapid, accurate, low-cost and noninvasive evaluation of final oocyte maturation and reproductive condition in common snook, Centropomus undecimalis (Neidig et al, 2000;Rhody et al, 2013). In addition, a system of preovulatory oocyte maturity has been proposed in Eurasian perch Perca fluviatilis (Zarski et al, 2011) and pikeperch Sander lucioperca (Zarski et al, 2012a) based on the nucleus position and the coalescence of oil droplets to improve the synchronization of ovulation.…”

Digestive Enzyme Activity during Larval Development of Black Snook, Centropomus nigrescens

“…The Centropomidae family has been widely studied since the 1980s. Efforts to understand their basic biology are ongoing to develop and improve captive culture techniques for commercial‐scale production (Grier ; Cerqueira and Brügger ; Alvarez‐Lajonchére et al ; Tarcisio et al ; Gracia‐López et al ; Wainwright et al ; Yanes‐Roca et al , ; Yanes‐Roca and Main ; Rhody et al , , ). Similar to common snook, Centropomus undecimalis , and fat snook, Centropomus parallelus , black snook has been identified as a potential candidate for aquaculture because of its high demand, size, and culinary value.…”