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Survey objectives

Survey objectives

The general objectives of the programme as discussed and agreed at the planning meeting in Trinidad, 12-14 January are as follows:

Describe the composition, distribution and abundance of the main components of the resources of small pelagic - and demersal fish and crustacea on the shelf and slope for studies of the state - and the potentials of the stocks.

Collect biological samples of the most important species for studies of growth, maturity etc.

Conduct taxonomic studies for the purpose of preparing a regional species guide.

Conduct oceanographic investigations and obtain satellite imagery for studies of the oceanographical regimes and their ecological characteristics.

Prepare charts based on echo sounder observations of bottom character.

Provide data of catch rates for specific selected gears and areas.

These overall objectives were to be amended and supplemented by the more specific requirements for each country or area and in the light of previous work done.

A number of fishing surveys have been conducted in the Guianas shelf area, most of them with bottom trawl, some with hand - or long lines. These have been targeted on the demersal fish and shrimp. The most recent important surveys are:

CALAMAR and FREGATA, 1967-70, (UNDP/FAO), all area.
OREGON II, 1972-77, (USA), Suriname-Guyana.
NISSHIN - MARU, No 201, 1982-83 (Japan), Suriname.
BONITO, 1980-81, (Germany), Suriname.
ORKNEY, 1980, (DDR), Guyana.
In addition to results of commercial interest, catch rates and simulation fishing data, the findings have provided the basis for studies of demersal fish assemblages in various parts of the shelf and estimates of the standing biomass of demersal fish and its composition.

None of the surveys have covered small pelagic fish although recordings and observations have been made. An acoustic coverage of this type of resource would thus seem to be an important objective for the present survey. Part of the demersal fish is also found in mid water, especially during the night, but for some species also in daytime (snappers). These could possibly also be included in the acoustic survey.

The acoustic coverage should be adapted to the distribution of the target resources for these investigations so that the highest survey intensities are in areas of high fish densities. This will be done by amendment of the basic survey grid on a current basis during the survey. Trawling with mid water and bottom gear for identification and sampling form an integral part of the acoustic survey work. In areas where snappers occur in mid water over hard bottom sampling with hand lines will be tried.

The acoustic system will only cover the part of the demersal fish found in mid water and non of the crustacean resources, although samples for composition, size etc. will be provided by the accompanying bottom trawl catches. In order to obtain further data on the demersal fish a number of trawl stations will be made in prelocated position. When targeted on demersal fish these hauls must be made in daytime.

Trawling for red spotted shrimp should be nocturnal while pink and brown shrimp can apparently be caught both day and night. This activity can not be expected to be on a scale which will allow estimates of standing stock, but results will provide biological sampling and some distributional characteristics.

The Japanese survey demonstrated the presence of some species of deep water shrimp on the slope off Surinam (and French Guyana): scarlet shrimp, Plesiopaeneus edwardsianus, 400-900m esp. 800-900m; spider shrimp, Nematocarcinus rotundus, 400-900m, esp. 700-900m; and megalops shrimp, Penaeopsis megalops, 150-500m esp. 300-400m. In this survey some test hauls can be made to confirm the presence of the megalops shrimp and for biological sampling. The best fishing ground were found between 53°30’ and 54°30’ at depth 290-380m, especially 53°30’ - 53°50’ at 310m. The slope further westwards may be explored for suitable trawl bottom in this depth range.

The various countries have submitted the following special considerations:

SURINAME. For the inshore - and shrimp surveys special attention should be given to the areas off the mouths of the large rivers: Maroni, Suriname, Coppename and Corentyn, and for the mid- and for offshore surveys to the central snapper ground between 30 and 40m and the snapper ground near the edge at about 80 to 100m.

GUYANA. Special efforts should be made to provide data for studies of the by-catch of the existing shrimp fisheries through bottom trawling on the shrimp grounds. The main season for the offshore shrimping starts in April-May and the next coming surveys may provide the best opportunity for work there. Also work on deep water shrimp is desirable although a 1980 survey with the DDR stern trawler “ORKNEY” found little suitable trawl bottom beyond 100m depth. There is need for information on the stocks of fin fish exploited by the artisan small scale fishery.

VENEZUELA. In the Orinoco Delta emphasis should be given to the collection of observations on the shrimps and the by catch in the shrimp fisheries, the last with special reference to the Sciaenid -, Lutjanid - and Scombrid species. In the Joint Fishery Area with Trinidad a preliminary survey should be made.


The following participated from the region:

Suriname: J. A. Emanuels, Heidi Jessurun
Guyana: Terrence Phillips, Maurice Phillips
Venezuela: L. W. Gonzales C., Diana Zaera
From FAO: Luis Villegas
The scientific staff from IMR was: G. Sætersdal, O. Alvheim, J. Kolding, T. Haugland and E. Molvær.

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