Acoustic observations of patterns of aggregation in haddock (Melanogrammus aeglefinus) and their significance to production and catch

摘要: A dual-beam acoustic system was used to collect detailed information on density and body size over a 24-h period in an area of the Scotian Shelf occupied by population large spawning haddock (Melanogrammus aeglefinus). The sampling showed persistent gradient decreasing with distance from bottom 50% fish < 2.5 m off bottom. Horizontally (scale hundreds metres), there high degree local aggregation which changed dramatically 24 h. Highest daytime, more dispersed throughout water column at night. differences time day appear be sufficient explain diel changes net catch rates. On larger geographic scales (tens kilometres), relatively uniform. Acoustics provide method for studying relative importance these various spatial estimates abundance. Haddock biomass also related organism size, as has been...