Observations on herring spawning and larval distribution in the Firth of Clyde in 1958

Abstract

Apart from the extensive egg surveys carried out by Norwegian workers (Runnstrom, 1941) most of the investigations on the spawning of the Atlantic Herring have depended on studies of the distribution of the spawning fish, on captures of newly hatched larvae, and on records of the occurrence of herring eggs in the stomachs of predatory fish species (principally haddock). With the exception of recent observations by Bolster and Bridger (1957), attempts to sample egg concentrations quantitatively in the North Sea and neighbouring areas have usually proved abortive. In consequence little is known of the distribution and density of eggs on the spawning grounds, their percentage fertilization, mortality during the egg stage, hatching rate, and the relationship between the distribution of eggs and the nature of the sea-bed.