3 research outputs found
Atlantic mackerel daily spawning dynamics and implications for batch fecundity estimations
The present study contributes to a better understanding of the daily spawning dynamics of southern NEA mackerel (Scomber scombrus) with
implications for the estimation of batch fecundity. It shows that there is a time window during the day, mainly in the afternoon, during which
the advanced oocyte mode in imminent spawners separates from the remaining, smaller oocytes. This synchronicity in the separation of the
spawning batch amongst imminent spawners corroborates evidence for the existence of daily spawning synchronicity in the population. This
is particularly important for applications of the daily egg production method, DEPM, because such pattern facilitates both the ageing of eggs
for the estimation of the daily egg production at sea and the ageing of postovulatory follicles for the estimation of spawning frequency. For
NEA mackerel, batch fecundity could only be measured when a clear hiatus was established between the spawning batch and the smaller oocytes. Hydrated females that do not show such hiatus would not be valid for batch fecundity measurements suggesting that the “hydrated
oocytes method” is not fully applicable for this stock. Knowing the time of day at which the batch is separated, will facilitate the sampling of
valid females for the estimation of batch fecundity