Publication Abstract

Field observations of the daily pattern of spawning in the western stock of mackerel (Scomber scombrus L.)

J.H. Nichols and S. Warnes

The daily pattern of spawning of mackerel was inferred from plankton samples taken during two periods in 1989 and again during two periods in 1991, in the western mackerel spawning area. The time of day that early-stage eggs in these samples were fertilized was calculated using data on their rate of development obtained from concurrent shipboard observations on artificially fertilized eggs. From these back-calculations of fertilization times of eggs up to 8 h old (32-cell stage) in 1989 and up to 9.4 h old (64-cell stage) in 1991, it was apparent that spawning might occur at any time of the day or night. Furthermore, there were no significant peaks in spawning at any time of the day or night. The absence of a diel periodicity in the spawning of mackerel has important implications for the use of the batch fecundity method to estimate total seasonal egg production in an area.

Reference:

J.H. Nichols and S.Warnes, 1993. Field observations of the daily pattern of spawning in the western stock of mackerel (Scomber scombrus L.). ICES Journal of Marine Science, 50: 219-225.