Growth and expansion of haddock (Melanogrammus aeglefinus L.) stocks to the west of the British Isles in the 1990s
A marked expansion of haddock (Melanogrammus aeglefinus) distribution and abundance to the west of the British Isles in the 1990s is described using fisheries landings and research survey data. The expansion appeared to begin at approximately the same time (1994-1995) across the region and led to the establishment of new fisheries on haddock in the Irish and Celtic Seas. Fish in different sea areas showed different characteristics of length at age, maturity, and recruitment patterns. Haddock in the Irish Sea were much larger (60 cm at age 5) than those west of Scotland (40 cm at age 5). Fifty percent of the females were mature at 27 cm in the Irish and Celtic Seas and at 22 cm to the west of Scotland. It is shown that these characteristics allow populations at the southern extreme of the species range in Europe to respond rapidly to more favourable conditions. Such conditions could have occurred over a large region allowing substantial growth of existing populations. Alternatively, introductions of ichthyoplankton by advection, or the spread of juveniles from densely populated areas, could take place to create a large self-sustaining introduced population in areas such as the Irish Sea. However, any mixing appears to have been limited as recruitment patterns differed among areas. Owing to the synchrony of the expansion in the different areas, it is concluded that some condition, or combination of conditions, changed to enable haddock to exploit resources in all the areas to the west of the British Isles in the late 1990s.
Article from Marine Science Symposia Vol. 219 - "Hydrobiological variability in the ICES Area, 1990-1999", symposium held in Edinburgh, 8-10 August 2001. To access the remaining articles please click on the keyword "MSS Vol. 219".