The egg production and spawning stock size of the North Sea mackerel and horse mackerel stocks in 1988

During the period 5 April to 28 July 1988 the spawning areas of North Sea\nmackerel and horse mackerel were investigated by research vessels from the\nNetherlands, Denmark and Norway. Based on the plankton samples and\ntemperature observations obtained during this period the egg production\nand spawning stock size were estimated. The total egg production of\nmackerel represents a spawning stock biomass of 37 000\ntonnes, which is about 20 % less than the 1986 estimate. The total egg\nproduction of horse mackerel represents a spawning stock\nsize of 110 000 tonnes.