Title Processed CTD continuous observations from the Shoal Ecology Cruise on the Africana Voyage 018, April 1984
Authors

Gavin Tutt
Oceans and Coastal Research, Department of Forestry, Fisheries and the Environment (DFFE); role: Marine Scientific Technician; contact details: email: Gtutt@environment.gov.za

Tarron Lamont
Oceans and Coastal Research, Department of Forestry, Fisheries and the Environment (DFFE); role: Marine Scientist; contact details: email: tlamont@environment.gov.za

Publisher Department of Forestry, Fisheries and the Environment (2022)
Contributors

Contact Person: Gavin Tutt
Oceans and Coastal Research, Department of Forestry, Fisheries and the Environment (DFFE); role: Marine Scientific Technician; contact details: email: gtsglider@gmail.com

Contact Person: Tarron Lamont
Oceans and Coastal Research, Department of Forestry, Fisheries and the Environment (DFFE); role: Marine Scientist; contact details: email: tarron.lamont@gmail.com

Abstract This is processed downcast Conductivity-Temperature-Depth (CTD) continuous data from the Shoal Ecology Cruise on the Africana Voyage 018 collected between 9 and 19 April 1984. The cruise operated in the Benguela Current Large Marine Ecosystem (BCLME) region on the west coast of South Africa. The objectives of this cruise were to obtain a broad picture of pelagic fish shoal distribution in relation to the prevailing mesoscale environmental features; to investigate intensively the diel shoal behaviour pattern of anchovy, pilchard and round herring, with particular reference to their feeding behaviour in relation to food supply. If time permitted the plan was to carry the investigation out in two areas of contrasting environmental features ie St Helena Bay and off Saldanha Bay. Shoals of fish close to strong environmental gradients (in a horizontal plane) will be surveyed to investigate the effect, if any, upon diel behaviour patterns on either side of the gradient. A number of extended lines, traversing the gradient will be steamed with plankton and fish being sampled on an ad hoc basis. It could well be that this investigation would be given a higher priority than the intensive survey off Saldanha.
Methods Neil Brown MK3 and MK4 Conductivity-Temperature-Depth (CTD) instruments were used to measure pressure, temperature and conductivity through the water column during research and monitoring cruises between 1983 and 2000. Temperature was converted from the IPTS-68 scale to the ITS-90 scale, and salinity was computed from conductivity measurements on the 1978 Practical Salinity Scale, according to UNESCO (1991) algorithms. UNESCO (1993) quality control procedures were applied to the data, and obvious erroneous values resulting from problems including electronic spikes, data collection in air, inadequate flow through the conductivity cell, among others, have been removed. Any additional calibrations or corrections have been specified in each data file, where applicable and available.
Data
Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
Temporal extent 09 Apr 1984 – 19 Apr 1984
Geographic extent

Benguela Current Large Marine Ecosystem (BCLME) region on the west coast of South Africa

North: -32.2
South: -32.7
West: 17.6
East: 18.4

Vertical extent Max: -94.7 m
Min: 0.0 m
Keywords Africana, Africana 018, Conductivity, CTD, Depth, Neil Brown CTD, SOUTH ATLANTIC OCEAN, Temperature
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