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4. Fish distribution

Figure 3 illustrates the distribution of all fish as observed with the acoustic integration system. This will mainly show the pelagic species. The units of acoustic reflection is 0.1 × m2/nm2 reflecting surface. This unit is not directly proportional to fish density since small sized fish gives a higher acoustic reflection per unit weight than bigger fish, but in gross terms Figure 3 gives a fair picture of the main distributional features of the small pelagic fish in the area. An arbitrary scale has been used to illustrate different levels of concentration. The acoustic data will later be used for biomass estimates.

The Suriname shelf.

As during the previous coverages the highest densities were found over the inner shelf areas. The aggregations consisted mainly of anchovies and various clupeids, of which Chirocentrodon bleekerianus was the most common in the catches.

Guyana.

The highest aggregations were found in the shallower waters, and consisted mainly of anchovies and various clupeids. One aggregation was found more offshore, at about 60 m bottom depth and consisted mainly of round sardinella (S. aurita).

Venezuela off the Orinoco Delta.

The distribution pattern registrated by the acoustic system was close to the one during the previous survey. Fish aggregations were only recorded in a narrow belt inshore in the depth range 20 - 30 m. Most of these were identified as anchovies with some clupeids.


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