The 1985-1986 surveys and objectives for the new surveys.
Under the same programme six seasonal surveys were made of the continental shelf of Angola between January 1985 and June 1986 with the general objective of investigating the composition, distribution and abundance of the coastal fish resources. The methods included acoustic integration technique to study the small pelagic schooling fish and a bottom trawling programme to investigate the demersal resources using the swept area method for abundance estimates.
The results from these surveys are described in preliminary cruise reports issued after the completion of each survey and in an investigational report presented at an Angolan national fisheries seminar in Luanda in March 1987. In this last report an account is given of the hydrographic situation during the survey period, and the findings regarding the composition, distribution and abundance of the resources are described for the various main groups of fish: small pelagic sardine-like fish, other small pelagic fish, demersal fish and the deep water slope resources. In conclusion some comments are offered on the state of the resources and their management situation.
The objectives for the new 1989 surveys were discussed with the director and other representatives of the Centro de Investigacao Pesqueira at a meeting in Luanda on 23 January 1989. The main purpose of the programme will be the same as that of the 1985/86 surveys, to provide as much information as possible about the composition, distribution and abundance of the components of the resources covered by the survey methodology. There is a special interest in obtaining new assessments of the stock biomasses of the important pelagic resources, described separately for the two groups: sardinellas and horse mackerels. The extent to which the southern pelagic stocks, sardine Sardinops ocellata and cape horse mackerel Trachurus capensis are shared between Angola and Namibia is of special interest and makes biomass estimates of these species in the southern region an important task. The main demersal species should be investigated by depth strata. Data on the component of juveniles of commercial species in bottom trawl catches are required for possible mesh regulations of the increasing Angolan fishery for consume fishes. As regards work on the deep slope some fishing experiments should be made in important shrimping areas to test catch rates for rose shrimp Parapenaeus longirostris, striped red shrimp Aristeus varidens and hake Merluccius polli for comparison with similar data from the 1985/86 surveys. The hydrographic programme comprising surface temperature distribution and profiles in standard positions should be worked as before. Observations on the bottom character along the cruise tracks will be compiled as previously and in addition attempts will be made to observe the type of bottom substrate using a new acoustic programme calibrated with grab samples.
Participation.
The scientific staff from CIP, Luanda was:
Antonio Fontes Pereira, Maria Antonia Nelumba, Geraldina de Assuncao Salvador, Manuel Domingos, Fransisco de Almeida and Kumbi Kuilomgo.The scientific staff from IMR was:
G. Saetersdal, O. Alvheim, Diana Zaera, M. Dahl and E. Molvaer.Narrative.
The vessel left Luanda 11 February and work commenced off Tombua in the morning of 13 February. Five days were spent covering the shelf down to Rio Cunene with an acoustic cum trawl survey and including the hydrographical profile off Baia dos Tigres and calibration of the acoustic instruments in the bay on 17 February. The weather conditions on the offshore and southern parts of the shelf although not favourable were workable. Very few fishing vessels were observed in the area.
The shelf from Tombua to Benguela was passed from 18 to 19 February. The work along this narrow shelf was not given high priority. Most parts of this coast has steep or rough bottom inaccessible to bottom trawling. The acoustic observations indicated relatively high availability offish from about Namibe southwards, but sampling must be done with mid water trawl at night. More work in this area should be considered for a later survey.
Figure 1 shows the course tracks with fishing stations and the hydrographic profiles.
ANNEX III gives a description of the acoustic instruments and the fishing gear used.
