DEEP-WATER SPAWNING OF ATLANTIC MACKEREL SCOMBER-SCOMBRUS, WEST OF IRELAND

Atlantic mackerel (Scomber scombrus L.) were sampled by pelagic trawl over the Porcupine Bank to the west of Ireland between 52 degrees N an d 54 degrees N at peak spawning time, between 27 May acid 10 June 1992 . Distribution of juveniles (age classes 1 and 2) was inversely relate d to depth, comprising over 90% of hauls close to the coast of Ireland and 20% of the catch on the Porcupine Bank. Egg production increased westwards and was high along the continental shelf edge. Adult spawnin g fish were found throughout the shelf area and beyond, into waters ov er 3000 m deep. The results indicate that mackerel spawn over deep wat er some distance from the shelf edge and may exploit oceanic food reso urces from deep water.