Tilapia Aquaculture. Proceedings from the Fourth International Symposium on Tilapia in Aquaculture, November 9-12, 1997, Orlando, Florida. NRAES-106: 683-700
Israel Rubinshtein; Shmuel Rothbard; William L. Shelton
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The Israeli Journal of Aquaculture
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Abstract: The duration of cytokinesis-1 (T), as measured in units of embryological age (intervals between consecutive and synchronous mitotic cell divisions), is termed to and is an important relationship in ploidy manipulations. T/to is constant and species specific in teleosts. Timing of shock initiation (ts) for intervention to retain extrusion of the 2nd polar body (2Pb), or for mitotic (late) intervention, is associated with cytokinesis-1 and can be referenced to to units. The present study compares effects of temperature determinants, which define T/to in nine fish species. The temperature dependence of embryological age to is expressed by the equation to = 10a x C-b. The equation corresponds with the Krogh’s curve, where the power coefficient b is equal to and replaced by T/to. A standard equation (St) was formulated to calulate T/to in fish species. The to equations were compared to the standard equation, using Q10-coefficients for oxygen demand of fish at four different temperatures: (alpha)- temperature limits of the fish’s distributional range, (beta)- the minimum temperature of reproduction as expressed by Krogh’s curve, (gamma)- the actual temperature of reproduction and (theta)- the temperture at which the T/to- curve intersects the standard curve.