Distribution and discrimination of anchovy, and sprat in the Black Sea from high frequency sound records

High frequency (200 kHz) was used to identify anchovy, and sprat schools from over the entire trackline of broad-scale acoustical survey over a period of 4 years (1991-1994) in the Bleak Sea. Analysis of color enhanced echograms as well as trawl catches provided detailed morphological descriptions to discriminate aggregations of anchovy, and sprat together with characteristics of their habitat. Sprat showed fish school scattered in relatively, a thin layer near the bottom like semi-pelagic fish made up. Anatomy of the aggregation did not change between day and night, and there was 110 diet shift in the habitat. Anchovy formed the pole shaped schools as well as compact aggregation arising from bottom around the shelf break area to that as much high up as 30-70 m, during the day. Additionally, a striking point is that the anchovy in an appearance, of what looked to be pole shape school, stand ready on top of submarine steep cliff to escape down immediately in case of any disturbance to the school. There is a sharp discrimination between the schools of sprat and anchovy.