240 SCIENCE IN AFRICA 



sole, which is the basis of a large commercial fishery. All these 

 grounds, with the exception of those off Natal, are suitable for 

 trawling; while in Natal waters, where the nature of the bottom 

 precludes trawling, line-fishing is practised. Survey work off the 

 South-West African coast has revealed a rich ground of large 

 extent, lying beyond the eighty-fathom line. 



Commercial fishing is carried out from the various smaller 

 centres by line-fishing boats, while modern steam trawlers, belong- 

 ing to three companies, operate from Capetown, Mossel Bay, Port 

 Elizabeth, and East London. Thus there are adequate harbour 

 facilities provided for trawlers, and rail transport of fish to the 

 inland centres is easy. In the past much fish which would be con- 

 sidered valuable in Great Britain has been shovelled overboard 

 dead, and it is possible that some of the grounds have been seriously 

 depleted. The division has recently completed investigations, how- 

 ever, into methods of saving immature fish, and the trawlers are 

 now using a larger mesh in the cod end of the otter trawl, whereby 

 waste is materially reduced. 



Fish is smoked, canned, dried, salted, and frozen by modern 

 methods, and locally produced products are largely replacing 

 imports. Smoked and frozen fish have been exported for some 

 time and the markets are steadily growing. The Cape crawfish 

 is also the subject of a considerable industry, and there are sixteen 

 canning factories for it on the west coast. Though hard hit by the 

 imposition of quotas in France, the industry is now exporting 

 canned crawfish to Canada and the United States of America, and 

 has also built up a considerable market for frozen crawfish tails. 

 Rigorous restrictions are imposed on the catching of undersized 

 crawfish and females in berry. There are certain proclaimed sanc- 

 tuaries wherein crawfishing is totally prohibited. Biological work 

 on the Cape crawfish is undertaken by the division of fisheries, 

 and papers on its natural history, reproduction, etc., have been 

 published by von Bonde (1935 and 1936). 



Before the war some detailed studies on the marine fauna of 

 South-West Africa were made by German students, and W. Michael- 

 sen of Hamburg (191 4 onwards) started a special series of publica- 

 tions which is still continuing. Papers by many experts are devoted 

 mainly to the taxonomy of invertebrate animals; their scope in- 



