Estimation of mackerel (Scomber scombrus L., 1758) and horse mackerel (Trachurus trachurus L., 1758) daily egg production outside the standard ICES survey area

An experimental egg survey was carried out to assess whether there was significant spawning of mackerel and horse mackerel outside the area surveyed triennially by the international mackerel and horse mackerel standard egg survey. In all, 170 stations were sampled in May 2002 on the Porcupine, Rockall, and Hatton Banks, over the Rockall Trough, and in Faroese waters, with 38 control stations inside and 132 stations outside the standard survey area. There was some spawning of mackerel south and cast of the Rockall Bank and southeast of the Faroe Bank, extending to west of the Scottish Shelf Limited horse mackerel egg production was found west of the Rockall Bank and south of the Faroe Bank. The total mackerel and horse mackerel daily egg production estimated from samples collected in 2002 outside the standard survey area was low compared with the egg production estimated in adjacent waters just inside the standard area in the same year and during the international standard surveys in May and June of 2001. The results suggest that including the spawning activity of both species outside the standard survey area would not significantly contribute to the total estimated egg production. (c) 2005 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.