La caballa (Scomber japonicus) y las condiciones ambientales en el area bonaerense de El Rincón (39°- 40°30' S), agosto 1996.
Castro Machado, F.
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In August 1996 acoustic methods were employed to estimate mackerel (Scomber japonicus) abundance in the Buenos Aires, Argentina shelf area of "El Rincón" (4,287 mn2), located between 39°- 40° 30' S. Results showed a biomass estimate of 77,260 t. ASIMRAD EK-500 equipment operated with a 38 KHz split-beam transducer was used. Midwater fishing trawls were employed to identify echotraces and to collect mackerel samples.Trawls 4 and 5 were the most successful. Samples included only adult fish (310-470 mm Lt and ages ranging 2-11). Length and weight growth parameters and mortality rates were estimated. Analysis of the stomach contents revealed that mackerel was feeding exclusively on zooplankters over 2 mmlength. The analysis of the characteristics (dimensions and density) of the mackerel shoals allowed to detect two areas of concentration above and below 40°S latitude. The northern area was characterized by relatively small schools of medium density similar to those of the Mar del Plata a.....