Sierra Leonehttp://hdl.handle.net/1834/173842024-03-28T11:50:10Z2024-03-28T11:50:10ZSize composition of the catches of the pink shrimp Penaeus duorarum notialis in the shrimp fishery of Sierra LeoneScott, R.B.S.http://hdl.handle.net/1834/235922021-07-14T01:54:48Z1978-01-01T00:00:00ZSize composition of the catches of the pink shrimp Penaeus duorarum notialis in the shrimp fishery of Sierra Leone
Scott, R.B.S.
Measurements were taken of size distribution of P. d. notialis collected off Sierra Leone over a period of six months from October 1977 to March 1978. From the frequency distribution curves it is observed that the curves for male shrimps show only one or two major modes, which show prominence between 12.5 and 14.1 cm of total length. Females mostly exhibited size groups with three or four different length ranges and occasional occurrence of 1 to 5 modes. These size groups were observed to show continuous changes. No one group could be said to be permanent. The point of entry into the fishery of male shrimps was found to be at an average total length of 10.5 cm, while females did so at 11 cm. Sex ratios in the different samples were usually 1:1 but in one case the males were more numerous by 2:1 and in four other samples females were significantly preponderent. These departures from the 1:1 ratio may have been artificially created by sorting of the catches on board the ships.
1978-01-01T00:00:00ZMarine biology of the Sierra Leone River Estuary. 1. The physical environmentFindlay, I.W.O.http://hdl.handle.net/1834/235832021-07-14T01:51:11Z1978-01-01T00:00:00ZMarine biology of the Sierra Leone River Estuary. 1. The physical environment
Findlay, I.W.O.
The Sierra Leone River Estuary is a relatively young drowned river valley, it is shallow except for a deep channel which passes close to the Freetown shoreline. The upper reaches merge into a network of creeks and channels fringed by large areas of mangrove swamps. It is a tidal estuary of the semi-mixed type with the saline oceanic water entering it on a diurnal cycle. The climate of Sierra Leone is marked by a very distinct change between a very wet rainy season and a dry season. The tidal range of the Estuary (spring 3.03m; neap 2.28m) does not impede normal use of the harbour. The tidal variations can be felt as far as 42 miles inland along the water courses of the Sierra Leone River and its tributaries. The volume of fresh water entering the Estuary is large during the rainy season and greatly reduced during the dry season. Consequently there is a marked fall in salinity during the rainy season and higher salinities due to the marine influence prevailing during the dry season. The nature of the shores and bottom, the hydrography and chemistry of the estuarine system have been outlined in relation to the prevailing climatic conditions.
1978-01-01T00:00:00ZMaking kippers from local herring (Sardinella spp.) smoke-cured in the Torry KilnMason, E.D.C.http://hdl.handle.net/1834/235792021-07-14T01:49:49Z1978-01-01T00:00:00ZMaking kippers from local herring (Sardinella spp.) smoke-cured in the Torry Kiln
Mason, E.D.C.
(Sardinella) are available all year round in Sierra Leone. The best time to use them for baiting herrings is during the dry season when they are fattest and feeding well. The most common method of processing herring locally is hot smoking to give either soft, moist and cooked product or a dry, brittle product with very low moisture content. The author describes a curing method intended to add variety to the types of products that can be obtained from local herring. It is only mildly preservative, the product cannot be kept more than 24 hours without refrigeration. Particular attention is paid to the source and quality of the raw material used, and the processing method is detailed with attention to washing, splitting, brining, smoking, and the application of the Torry fish smoking kiln to the process.
1978-01-01T00:00:00ZThe effect of sublethal concentration of DimilinR (TH6040) on the larval development of the mud-crab Rhithropanopeus harrisii (Gould)Wilson, J.E.H.http://hdl.handle.net/1834/232852021-07-12T02:55:51Z1978-01-01T00:00:00ZThe effect of sublethal concentration of DimilinR (TH6040) on the larval development of the mud-crab Rhithropanopeus harrisii (Gould)
Wilson, J.E.H.
Sublethal DimilinR (insecticide) concentration significantly decreased the percentage survival of larval R. harrisii . This decrease was marked at low salinities, when it may have become toxic. This was true for both 25 and 30 C. Duration of larval development did not seem to be affected by sublethal DimilinR concentrations even in extremely low or high salinities. High temperature, however, shortened the time of development. No anatomical abnormality was observed. These findings are only tentative as more replicates of the experiments are needed before definite conclusions can be reached. It will be desirable to work with more salinity-temperature combinations to get a complete picture of sublethal effects under different environmental conditions.
1978-01-01T00:00:00Z