Results of a stratified random bottom trawl survey for scad and mackerel in Mozambican waters, from May to June 1984

The total abundance of small pelagic species in Mozambican waters was estimated to be 100 (plus or minus 45) thousand tonnes of which scad and mackerel constituted 57 (plus or minus 39) thousand tonnes. These abundance estimates must be considered as minimum estimates of biomass as the efficiency of the trawl was assumed to be equal to 1.0.

Results of a random stratified bottom trawl survey for scad and mackerel stocks in Mozambican waters: small pelagic fish December-January 1985

The results obtained during the third phase of Nauka are reported concerning the standing stock estimates, population length structure and gonad development of scad and mackerel stocks and the catch composition in Mozambican waters.

An assessment of the stock of scad and mackerel at Sofala Bank and Boa Paz, Mozambique

The fishery for scad and mackerel along the coast of Mozambique began as a licensed fishery in 1977. In 1980, Mosopesca, a joint venture between Mozambique and the Soviet Union was formed and the licensed fishery ceased. Mosopesca started fishing with four vessels, but since 1984 the number of vessels has gradually been increased and at the end of 1985 a total of seven vessels was in operation. This report contains an updated assessment based mainly on information collected from July 1984 to May 1986.

Estado actual da pescaria de camarāo no Banco de Sofala

A summary of the shrimp fishery history as well as the most important recommendations for the period 1977-1990 is presented. During the last years the catch rates have decreased. Although many possible causes can be appointed, such as, weather conditions and increase of effort, there is no clear explanation for it. A relationship between catch rates in the main period of recruitment (January to March) and the level of recruitment of the same year was established. Based on this relationship, the total annual catch is predicted for the level of fishing mortality chosen. Fishing mortality is estimated as 2.28 yearˉ¹ and a gradual reduction of fishing effort is recommended until 2.17 yearˉ¹ calculated as F(sub)0.1.

Análise dos efeitos da introduçāo de medidas de gestāo na pescaria de camarāo do Banco de Sofala

Biological effects of management measures introduced in the shrimp fishery from 1985 to 1990 are analysed as well as the results from simulation of different closed seasons. Observed changes in recruitment, total catch, biomass and average individual weight during 1985 to 1990 for Penaeus indicus and Hetapenaeus Monoceros are also analysed. Further studies on a stock-recruitment relationship are important due to decline of recruitment levels in this period. A three-month closed season starting in January is recommended, without increases in the monthly fishing effort. The TAC shall be fixed according to the recruitment level each year.

Population dynamics of Penaeus indicus at Sofala Bank, Mozambique: a preliminary study

Length-based methods are used to estimate growth and mortalities of Penaeus indicus at Sofala Bank in Mozambique. This Penaeid shrimp is one of the most important species in the fishery as it constitutes 45% of the catches and has a great influence in their trend. First estimates of growth parameters for this species in Mozambique are presented and a comparison of the derived mortalities with the previous estimates is made.

Stock assessment of the deep-water spiny lobster Palinurus delagoae, off Mozambique

Preliminary estimates of growth parameters and mortality are presented for the deep-water spiny lobster Palinurus delagoae fished off Mozambique. The length-converted catch curve shows three levels of total mortality (year-1): Z=2.9 for the smaller sizes; Z=1.4 for intermediate, and Z=0.6 for the larger lobsters. These results are confirmed by a length-structured virtual population analysis. Yield-per-recruit analysis suggests that a long-term yield, at least 50% higher than the present one, could be obtained by increasing the mean size at first capture from about 6 cm (carapace length) to about 10 cm.

Seasonal growth of five commercially important fishes at Sofala Bank, Mozambique

An analysis of growth of scad and mackerels on Sofala Bank, Mozambique, was performed using data collected from commercial vessels during the year 1986-87, using the "Compleat Elefan" software package. Updated estimates of growth parameters of Decapterus russelli, D. macrosoma (Carangidae), and Rastrelliger kanagurta (Scombridae) were obtained which take seasonal growth oscillations into account. Preliminary growth parameter estimates are also presented for Selar crumenophthalmus (Carangidae) and Saurida undosquamis (Synodontidae).

Relatório do cruzeiro realizado no Banco de Sofala pelo navio "Pantikapey" de 7-23/Junho/1981: peixes demersais e fauna acompanhante de camarāo

Catch composition and bathymetric distribution of demersal fish caught along the coast of Mozambique between parallels 16 degree 20' and 19 degree 30' S at depths of 11 to 180 metres are given. The shrimp by-catch was also studied.

Relatório do cruzeiro realizado no Banco de Sofala pelo navio "Pantikapey" de 7-23/Junho/1981: peixes pelágicos e fauna acompanhante de Carapau e Cavala

This report of the research cruise (7 to 23 June 1981) surveying pelagic marine resources of the Sofala Bank (Mozambique) describes the size composition, distribution, length-weight relationships and sex-ratio of the fish captured. Decapterus russellii, D. macrosoma, Selar crumenophthalmus and Rastrelliger kanagurta represented 21.7% of the total catch. The by-catch was also studied.

Relatório do cruzeiro realizado no Banco de Sofala pelo navio "Pantikapey" de 21 de Julho a 7 de Agosto de 1981: peixes pelágicos e fauna acompanhante de Carapau e Cavala

This report of the research cruise (21 July to 7 August, 1981) surveying pelagic marine resources of the Sofala Bank (Mozambique) describes size composition distribution, length-weight relationships and sex-ratio of the fish captured. Decapterus russellii, D. macrosoma, Selar crumenophthalmus and Rastrelliger kanagurta represented 21.7% of the total catch. The by-catch was also studied.

Relatório do cruzeiro realizado no Banco de Sofala no barco "Meleia" em Agosto de 1981: camarāo de águas pouco profundas

The geographic and bathymetric distribution of the shrimps Penaeus indicus, Metapenaeus monoceros, P. japonicus and P. monodon along the coast of Mozambique are given. Biological data of the main species P. indicus and M. monoceros are presented.

The biology and availability of the spiny lobster Palinurus delagoae Barnard, off the coast of Mozambique

Catch and effort data and some biological characteristics of the deep water spiny lobster P. delagoae collected between August 1980 and December 1981, are presented. The work was conducted on board a commercial vessel off the coast of Mozambique.

Reproduction, age and growth of the kelee shad, Hilsa kelee (Cuvier, 1829) (pisces: fam. Clupeidae) with informations on its fishery in Maputo Bay, Mozambique

Age, growth and reproduction of H. kelee were studied, and a brief description of its fishery in Maputo Bay (Mozambique) is given. Most material was collected from gill net fisheries during 1977-1980, but some was taken from shrimp trawlers operating in the same area during 1980-1981. Main spawning takes place during October-January with a peak in December. There is also some evidence that spawning takes place during June-July. The size at first maturity was approximately equals 14-15 cm. Ageing was carried out using primary growth rings in the otoliths and length-frequency analysis of fish caught by shrimp trawlers. Von Bertalanffy's growth equation parameters were determined. Males and females grew in similar fashion. There are seasonal trends in the catch composition of the gill net fishery, showing high values during April to September and low during October to December.

Reproduction, age and growth of the Russell's scad, Decapterus russellii (Rüppel, 1828)(Carangidae) from Sofala Bank, Mozambique

Age, growth and reproduction of D. russellii were studied. Most of the material used was caught by the commercial fishing fleet, operating in the Sofala Bank (Mozambique) area. A total of 68,000 fish were examined during the period 1979-1981. There were 2 main spawning periods each year, one in February-March and another in August-September. The sex ratio was about 1:1. Ageing was carried out using primary growth rings in the otoliths and analysis of size-frequency distributions. The parameters of the von Bertalanffy's growth equation were determined. Males and females grew at the same rate.