Industrial fishery at sea
A shrimp fishery in Ghana has certainly existed for very long. Until 1968, exploitation was carried out only sporadically, with industrial boats coming from other countries but without discharging their catches in Ghana. A few boats from the Ivory Coast sometimes fished in the Axim Cape, Three Points and Keta areas, and others based in Benin worked in the Keta and Cape St. Paul area.
In 1969-70, Continental Seafood commissioned five trawlers which operated until 1972. This company wound up its activity when catch rates were getting too low. In 1971, Mankoadse Fisheries Ltd. commissioned two shrimp trawlers but catch rates were so low that the boats were transferred to Nigeria. In 1972, Ameyi Fisheries Ltd. commissioned for Ghana modern shrimp trawlers which were also converted into fish trawlers, due to low catch rates. In 1976, Alpha Fisheries Ltd. commissioned trawlers for the shrimp fishery; they fished for shrimps only a few months. For want of adequate catch rates, they had to convert into trawling for fin fish.
Artisanal fishery in lagoons
It was observed that in 1967 and 1968, shrimping by artisanal fishermen was active in the Keta lagoon, which was opened to the sea by a canal. In 1969, this canal was closed; fishing went on for some time in the lagoon, then stopped. Since then, some activities have existed in some estuaries only but catches are insignificant.
Shrimp fishing is practised in lagoons with stakenets, bamboo traps and small hand trawls. Catches can also be made through beach seines on the coastline in the neighbourhood of lagoons and rivers. The bulk of the catches, consisting mainly of Parapenaeopsis atlantica, is caught by the artisanal canoe fishery and by trawlers at sea accidentally.
It is interesting to note that the very low catch-rates of Penaeus duorarum obtained in the Keta area by the trawlers seem to be linked to the closing of the canal which was previously opened to the sea. The catches per unit effort of Ivorian shrimp boats in 1970 still averaged 10.7 kg/trawling hour. They dropped to 6.5 kg/h in 1971 and the successive failures to establish an industrial shrimp fishery in Ghana should be attributed to the reduction of catch rates as a consequence of the closure of the canal. Another consequence was the increase observed from 1969 to 1971 in the average size of Penaeus duorarum in the lagoon, the average carapace length of females increasing from 18 mm to 30 mm before the reduction of the population and catches. This increase in the average length can probably be attributed to the ageing of the population trapped in the lagoon by the closure of the canal (Figure 10).
The P. atlantica potential in Ghana seems important. It appears that the P. duorarum potential will remain low as long as the lagoons are kept closed.
Table 4.1
CPUE OF IVORIAN SHRIMP TRAWLERS IN GHANA (IN kg/h OF HEADS-ON SHRIMPS)
|
|
1970 |
1971 |
|
January |
|
|
|
February |
|
4.9 |
|
March |
13.0 |
4.1 |
|
April |
12.3 |
3.7 |
|
May |
9.6 |
7.1 |
|
June |
14.9 |
4.3 |
|
July |
15.9 |
9.9 |
|
August |
11.4 |
9.0 |
|
September |
9.6 |
5.2 |
|
October |
7.4 |
9.9 |
|
November |
7.7 |
6.7 |
|
December |
5.5 |
|
Table 4.2
GHANA’S CATCHES (1967/1976, HEADS-ON SHRIMPS (tons))
|
|
1967 |
1968 |
1969 |
1970 |
1971 |
1972 |
1973 |
1974 |
1975 |
1976 |
|
P. duorarum |
0 |
0 |
40 |
190 |
0 |
20 |
83 |
91 |
10 |
11 |
|
Mixed 1/ |
240 |
248 |
569 |
278 |
469 |
575 |
401 |
700 |
412 |
726 |
|
TOTAL |
240 |
248 |
609 |
468 |
469 |
595 |
484 |
791 |
422 |
737 |
1/ Consisting mainly of P. atlantica.
