| Title | Processed CTD discrete observations from the West Coast Hake Biomass Survey on the Africana Voyage 075, July 1989 |
|---|---|
| Project | West Coast Hake Biomass |
| Authors |
Mbulelo Makhetha Gavin Tutt Tarron Lamont |
| Publisher | Department of Forestry, Fisheries and the Environment (2023) |
| Contributors |
Contact Person: Gavin Tutt |
| Abstract | Here we present processed Conductivity-Temperature-Depth (CTD) discrete data from the upcast collected between 14 July and 17 August 1989 during Voyage 075 on the FRS Africana, in the Benguela Current Large Marine Ecosystem (BCLME) region on the west coast of Southern Africa. Neil Brown MK3 and MK4 CTD instruments were used to measure pressure, temperature and conductivity through the water column during research and monitoring cruises between 1983 and 2000. The objectives of the West Coast Hake Biomass Survey were to survey by means of trawling the abundance of adult and recruiting hake in South African waters; to investigate the diurnal cycle of hake and other demersal species; to investigate the environmental and ecological interrelationships of hake and demersal species; to make some experimental trawls in deep water to determine hake distribution limits and to collect deep-water specimens of fish and squid; to collect routine biological material on demersal species from South West African waters; to investigate the occurence, distribution and abundance of squid and squid larvae; to study demersal community interrelationships; to study the biology of sharks and selected non-commercial fish species; to investigate zooplankton scattering layers and their influence on the feeding behaviour of small hake and to extend the primary production data further offshore as well as north and eastwards from the Cape Peninsula - Cape Columbine area. |
| 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 | |
| Temporal extent | 14 Jul 1989 – 16 Aug 1989 |
| Geographic extent |
Benguela Current Large Marine Ecosystem (BCLME)
North: -28.5 |
| Vertical extent |
Max: -881 m Min: -0.01 m |
| Keywords | Africana, Africana 075, Conductivity, CTD, Depth, Neil Brown CTD, SOUTH ATLANTIC OCEAN, Temperature |
| Related resources |
|