METHODS OF HARVESTING CLUPEIDS AND TILAPIA IN LAKE KAINJI
A report prepared for the Lake Kainji Research (Man-made Lake) project
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
TABLE OF CONTENTS
This is one of a series of reports prepared during the course of the UNDP project identified on the title page.
The conclusions and recommendations given in the report are those considered appropriate at the time of its preparation. They may be modified in the light of further knowledge gained at subsequent stages of the project.
The designations employed and the presentation of the material in this document do not imply the expression of any opinion whatsoever on the part of the United Nations or the Food and Agriculture Organization of the United Nations concerning the legal or constitutional status of any country, territory or sea area, or concerning the delimitation of frontiers.
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1.1 Terms of Reference
1.2 Background Information
2. THE CLUPE1D FISHERY
2.1 Initial Experiments with a Kid-water Trawl
2.2 Exploratory Fishing
3. TILAPIA FISHERY
3.1 Gill Nets
3.2 Seine Retting
4. CONCLUSIONS ADD RECOMMENDATIONS
LIST OF TABLES
1. Mid-water Trawl with 12 mm Cod-end Weight in Grammes
2. Mid-water Trawl Weight in Grammes
3. Results of the Exploratory Mid-water Trawling Programme
LIST OF FIGURES
1. Mid-water Pair Trawl No. 1
2. Rigging and Towing Arrangement for Mid-water Pair Trawling
3. Mid-water Pair Trawl No. 2
4. Mid-water Pair Trawl Suitable for Commercial Use
5. (a) Mid-water Pair Trawling (The Cod-end is thrown into the water and the remnant of the gear shot while the two boats maintain a straight course)
(b) Mid-water Pair Trawling (The boats are separating just after shooting the net)
(c) Mid-water Pair Trawling (Last phase of shooting. The headline is Still visible at the surface
6. (a) Midwater Pair Trawling (15 hp units towing mid-water trawl. One wooden planked boat built at project. One glass fibre Yamaha 18 ft.
(b) Midwater Pair Trawling (Hauling the midwater trawl - 15 hp units - The two big floats mark the upper wing tips)
(c) Midwater Pair Trawling (Last phase of hauling. The cod-end with catch is hoisted over board)
7. (a) Mid-water Pair Trawling (Echo-sounder of SEA ROVER passing over trawl in action. Headrope at 11 m. Footrope at 18 m. Net opening height is 7 m)
(b) Mid-water Pair Trawling (The warp length is adjusted so as to maintain the mid-water trawl at the level of the fish traces)
8. Map of Kainji Lake - showing the sampling stations
9. Underwater Topography as recorded by echo-sounder showing old river bed and submerged trees (indicates narrow section of old river bed with tree lined banks fish echoes between 3 m and 7 m approximately.)
10. (a) Beach Seining (Beaches cleared at low lake level May he used for beach seining as the water level rises)
(b) Beach Seining (Rowing boat with net board across transom simplifies the work of shooting the beach seine which when operated from a canoe required the work of four men)
(c) Beach Seining (Exposed sand banks in the Foge Island area provide suitable sites where beach seines may be used during the low water period)
11. (a) Beach Seining (In the later stages of the haul, many fish are lost over the headrope)
(b) Beach Seining (The headrope is lifted above water as an attempt to prevent loss of fish)
(c) Beach Seining (Typical catch of Tilapia at Foge Island Beach Seine with 100 mm mesh size in bunt)
12. Tilapia Beach Seine - construction drawing
13. 16 ft Seine Netting Skiff (for Kainji Lake)
14. 27 ft Fishing Boat (for Kainji Lake)