| Title | Processed CTD discrete observations from the West Coast Hake Biomass Survey on the Africana Voyage 069, January 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 05 and 26 January 1989 during Voyage 069 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 West Coast Hake Biomass Survey was multi-disciplinary. The main target was to determine, by means of the swept area method, the present status of the hake resource on the South African west coast. In carrying out this study, it was possible also to collect some information on the environment and zooplankton (including squid larvae) in the vicinity of the catches and to determine some ecological interrelationships of hake and other demersal fish species, to investigate squid distribution, to study some aspects of the biology and distribution of sharks and skates, to study the feeding ecology of demersal species of little commercial importance and to look closely at demersal communities. A diurnal study was also carried out successfully and some deep-water trawls were made to collect rare and interesting specimens. While in South West African waters, a comparison of the trawling capabilities of the M.F.V. Chica Touza and R.S. Africana was attempted and much biological material was collected for routine studies of demersal fish in those waters. Throughout the cruise, otoliths and squid beaks were collected for stomach content studies, and in-depth research was conducted into horse mackerel. |
| 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 | 05 Jan 1989 – 24 Jan 1989 |
| Geographic extent |
Benguela Current Large Marine Ecosystem (BCLME)
North: -22.5 |
| Vertical extent |
Max: -554 m Min: -0.04 m |
| Keywords | Africana, Africana 069, Conductivity, CTD, Depth, Neil Brown CTD, SOUTH ATLANTIC OCEAN, Temperature |
| Related resources |
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