14.1 Current investigations and expected results
14.2 Recommendations
In August 1978 a Soviet vessel started a research program with special emphasis on larger pelagic fish species within the economic fisheries zone of Mozambique. These investigations are expected to increase the information about larger offshore pelagic species such as tunas, billfish and sharks. The project will probably not include information on larger pelagic fish in shallower waters. such as the Spanish mackerel.
On a joint basis, a Mozambican and Japanese enterprise is carrying out exploratory fishing for spiny lobsters and crabs. The investigation started in October 1978 and is expected to give information on the distribution and abundance as well as biological characteristics of those species.
About 12 Soviet trawlers are fishing under license for fish mainly on the Sofala Bank. The data from these fisheries are being treated by a joint team of Mozambican and Soviet scientists. Total catch, catch per unit effort, as well as species composition and biological information on the main species, are expected results from this study.
A research vessel from the German Democratic Republic will probably start investigations for 3-4 months in March 1979. For the moment it is not clear what kind of investigation the DDR research vessel will perform. In connection with this survey some DDR trawlers will carry out exploratory fishing, especially for the deep-water shrimp. The data from this fishery will offer possibilities to improve the assessment of the deep-water shrimp stock.
a) There is nearly complete lack of information on inshore and reef fisheries. The coast between Cabo Delgado and Angoche is edged by coral reefs and unsuitable for trawling. We therefore recommend a survey to be carried out covering the reef areas along the northern part and the inshore areas along the rest of the Mozambican coast. The inshore areas also include the mangrove swamps. The object should be to survey the present fishery in these areas and the possibilities to expand it. The survey could be carried out by a rather small vessel carrying a variety of gears such as traps, lines, nets etc.b) A sampling program on commercial shrimp trawling should be initiated to investigate closer both the magnitude, the species composition, as well as some biological characteristics of the by-catch of fish. The geographical and seasonal variations of the by-catch should be studied. Changes in the fish stocks of the shallower part of Sofala Bank will be reflected in the by-catch from the shrimp fishery. This information, together with data from the Soviet trawlers, offers a valuable tool in management of the most important fish stocks.
c) Efforts should be made to establish a monitoring program for the fisheries resources of the shelf zone. For the demersal stock, probably one trawl survey each year covering the main fishing areas will be sufficient, as the seasonal fluctuations of this stock seem to be small. The large seasonal variations in the pelagic stock, however, suggest that more frequent investigations are needed. For the latter an acoustic survey appears to be most appropriate. The possibilities of arranging such surveys should be investigated either on a national or regional basis. Regional investigations are to be preferred, as the stocks migrate from one area to another.
d) Exploratory fishing using pots in deeper water should be performed. This investigation could be carried out for fish down to 200 m, for crayfish and spiny lobsters down to 500 m, and for deep-water crabs down to 800-1000 m.
e) We recommend future hydrographic work to be concentrated on the shelf area. One or two fixed hydrographic sections covering the core of the Mozambique Current should be established to follow the seasonal and inter-annual variations. A more detailed study covering the distribution area of the main fish stocks should be carried out on Sofala Bank. The object of this investigation should be better knowledge of the general oceanographic circulation. with special emphasis on the possible influence of the major rivers on the recruitment mechanism of the shallow-water shrimp stock. The study should include ordinary hydrographic parameters as well as current measurement and mapping of the bottom surface sediments.
