Horse Mackerel Hydroacoustic Pilot Survey on the Africana Voyage 096, October 1991

The Horse Mackerel Hydroacoustic Pilot Survey was conducted on the Africana Voyage 096 from 14-28 October 1991. The objectives of the cruise were to test the feasibility of obtaining an acoustic estimate of adult horse mackerel; to assess the ability to determine target detectability, target identification and target strength; to obtain an estimate of horse mackerel abundance in a sub-region. The size of the sub-region were to be determined by the time available and on the results of the first two objectives; to collect biological data pertaining to horse mackerel; to measure currents by means of the Acoustic Doppler Current Profilers (ADCP) in order to: a) test for relationships between horse mackerel movement and near-surface and mid-water currents, and b) to add to the ADCP data base for the South East coast; to measure thermal and salinity structure of the water column using a Conductivity, Temperature, Depth (CTD), and measurement of basic biotic parameters; oxygen, nutrients and chlorophyll; to collect data from the satellite imager on the large-scale influence of the Agulhas current; to obtain a 'snap shot' view of the species diversity and stratification of mesopelagic fish and squids at a point east of the southern Agulhas Bank, in the region of the Agulhas retroflextion.