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  • 1
    Publication Date: 2021-06-27
    Description: Estimation of individual egg production (realized fecundity)is a key step either to understand the stock and recruit relationship or to carry out fisheries-independentassessment of spawning stock biomass using egg production methods. Many fish are highly fecund and their ovaries may weigh over a kilogram; therefore the work time can be consuming and require large quantities of toxic fixative. Recently it has been shown for Atlantic cod (Gadus morhua) that image analysis can automate fecundity determinationusing a power equation that links follicles per gram ovary to the mean vitellogenic follicular diameter (the autodiametric method).In this article we demonstrate the precision of the autodiametric method applied to a range of species with different spawning strategies during maturation and spawning. A new method using a solid displacement pipette to remove quantitative fecundity samples (25, 50, 100, and 200 milligram [mg]) is evaluated, as are the underlying assumptions to effectively fix and subsample the ovary. Finally, we demonstrate the interpretation of dispersed formaldehyde-fixed ovarian samples (whole mounts) to assess the presence of atretic and postovulatory follicles to replace labor intensive histology. These results can be used to estimate down regulation (production of atretic follicles) of fecundity during maturation.
    Keywords: Biology ; Ecology ; Fisheries
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 148-164
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  • 2
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    In:  aqdchief@seafdec.org.ph | http://aquaticcommons.org/id/eprint/18757 | 17342 | 2015-11-15 15:48:54 | 18757 | Southeast Asian Fisheries Development Center, Aquaculture Department
    Publication Date: 2021-07-11
    Description: Experiments were undertaken to assess the survival, spawning, fecundity and nauplii production of ablated P. monodon females reared in flow-through broodstock tanks with white coralline and black sand substrate for 62 days. The similar trend observed in mortality rates in both substrates suggests that variation in substrate material for broodstock tanks is not a likely cause of prawn mortality. There were also no significant differences observed between rematurtion rates, i.e. number of spawnings, under the different treatments. Singnificantly higher nauplii production were observed in females in tanks with white substrates. At present, the land-based broodstock tanks in SEAFDEC utilize white coralline substrates due to higher hatching rate of eggs and nauplii production, convenience in siphoning out debris and excess food that tend to accumulte in the tank, and contrast provided by the white substrate during nightly observations of ovaries.
    Keywords: Aquaculture ; Biology ; Crustacean culture ; Fecundity ; Spawning ; Substrata ; Penaeus monodon
    Repository Name: AquaDocs
    Type: article
    Format: application/pdf
    Format: application/pdf
    Format: 20-22
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