|Morpho-physiological predictors of ovulatory success in captive striped bass Morone saxatilis|
Weber, G.M.; King V, W.; Clark, R.W.; Hodson, R.G.; Sullivan, C.V. (2000). Morpho-physiological predictors of ovulatory success in captive striped bass Morone saxatilis. Aquaculture 188: 133-146
In: Aquaculture. Elsevier: Amsterdam; London; New York; Oxford; Tokyo. ISSN 0044-8486, more
|Authors|| || Top |
- Weber, G.M.
- King V, W.
- Clark, R.W.
- Hodson, R.G.
- Sullivan, C.V.
This study evaluates morpho-physiological characters as predictors of ovulatory success in cultured striped bass, Morone saxatilis, that could be used by farmers to select females for induced spawning. Diameter, size homogeneity and growth of ovarian follicles; blood plasma levels of testosterone (T), oestradiol-17 ß (E2) and vitellogenin (VTG); and in vitro maturation of oocytes, in response to a combination of insulin-like growth factor-I (IGF-I, 100 nM) and 17,20ß, 21-trihydroxy-4-pregnen-3-one (20 ß-S, 290 nM) were examined for females prior to spawning induction and compared with their subsequent ovulatory response. Fish spawning within 8 days of implantation with pelleted analogue of mammalian gonadotropin-releasing hormone analogue (GnRHa; [D-Ala6-des-Gly10-NEt] -LHRH) were considered to have given a satisfactory maturational response. The in vitro assay was the most reliable predictor for ovulatory success. All fish whose oocytes completed final oocyte maturation (FOM) in vitro in response to the combination of IGF-I and 20 ß-S spawned, whereas, 12 out of 13 fish, whose oocytes did not complete (FOM) in vitro, failed to spawn within 8 days of GnRHa treatment. The in vitro assay was field-tested on commercial farms, and correctly identified all four females that spawned out of the eight females that were given hormone treatment. Among the other measurements, follicle diameter best differentiated between fish that later spawned and those that did not spawn. Plasma T concentrations were greater on average in fish that spawned, but the technical complexity of the assay and overlap in T concentrations between fish that spawned and those that did not limits the value of this measurement to farmers. There was no significant difference in follicle size homogeneity, follicle growth over the 2-week period prior to hormone treatment, or plasma levels of E2 and VTG between fish that spawned and those that did not.