1. Introduction

Objectives for the survey

The objectives for the 1989 surveys were discussed with the director and other representatives of the Centro de Investigaçào 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 fisheries 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.

A first servey of the continental shelf of Angola was made in February-March this year and the results showed a marked decline in the stock biomasses of the sardinellas and the Cunene horse mackerel as compared to the 1985/86 servey results. Repeated assessments of these stocks represent therefore a task of high priority in the second survey. A detailed coverage of the Cunene-Tombua shelf to assess the joint stocks with Namibia will be repeated and extended to cover the shelf between Tombua and Namibe.

Participation

The scientific staff from CIP, Luanda was:

Francisca Alberta Delgado, Lutuba N'silulu, Geraldina De Assuncao,
Monica Do Ceu Ramos Da Cruz and Abilio Jornal.

J. Hamre, T. Haugland, K. Strømsnes, A. Totland and H. Ullebust.

W. Schneider.

The vessel left Luanda 21 April and work commenced off Santa Marta 23 April. Seven days were spent to cover the shelf from Rio Cunene to Benguela, with an acoustic cum trawl survey and including an hydrographical profile off Baia dos Tigres and calibration of the acoustic instruments in the bay on 26 April. 1200 n.m. were steemed and 43 trawl stations worked. The weather conditions were favourable. Some few fishing vessels were observed, mostly in the area Cunene-Tombua. The shelf from Tombua to Benguela was passed from 28 to 30 April. Most parts of this coast has steep or rough bottom, inaccessible to bottom trawling. The acoustic observations indicated relatively high availability of horse mackerel along the edge from about Namibe southwards, but sampling is difficult because the fish avoid the midwater trawl even by night, and the use of bottom trawl is very restricted.

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.