REPORT ON TRAWLING SURVEYS ON THE 

 PATAGONIAN CONTINENTAL SHELF 



Compiled mainly from manuscripts left by the late E. R. Gunther, M.A. 



By T. John Hart, D.Sc. 



(Text-figs. 1-53, Plate XVI) 



INTRODUCTION 



THE Patagonian Continental Shelf extends from the River Plate in the north to Staten Island in 

 the south, and from the South American coast to an average distance of some 250 miles offshore to 

 the eastward.' Outlying areas with depths of less than 200 m. extend round the Falkland Islands and 

 on the Burdwood Bank to the south. Beyond the 200 m. contour, which may be taken as the edge of 

 the shelf, the descent to oceanic depths is more or less abrupt. Faunistic writers referring to the 

 Patagonian region commonly include the Magellan Channels and the coast of southern Chile m their 

 geographical unit, but there is no need to qualify our definition of the Patagonian Continental Shelf 

 so as to exclude the west coast, for there the descent to oceanic depths is so immediate that a shelf 

 (in the accepted meaning of the term) can scarcely be said to exist. The investigations to be described 

 here covered the whole of the shelf south of lat. 42° S., an area of some 150,000 square miles which 

 is larger than the entire North Sea. Except for descriptions of small collections made in coastal 

 waters the marine fauna of the region was almost unknown when the Discovery Investigations began, 

 although it constitutes the largest expanse of shoal water (accessible to trawling) in the 'cold tem- 

 perate' or sub-Antarctic Zone of the southern hemisphere. 



The need for a fisheries survey of the shelf, to gain information on the prospects of developing a 



commercial fishery from the Falkland Islands, was recognized from the outset of the Discovery 



Committee's work (Kemp, in Kemp, Hardy and Mackintosh, 1929, P- 148)- The greater urgency of 



problems relating to whaling and sealing in the more southerly (Antarctic) waters of the Falkland 



Islands Dependencies limited the scope of the trawling surveys however, and combined, with Mr E. R 



Gunther's untimely death in 1940, to prevent publication of results until now. Vast collections of 



benthos with lesser but probably representative collections of plankton and hydrological data, were 



obtained Gunther had hoped to use the information gained from these, as they were worked up by 



various specialists, in presenting the ecological study of the fish fauna in much greater detail than can 



now be attempted. Continued work on many of the groups may not be possible for years, but by great 



good fortune the taxonomic revision of the fishes had been completed by the late Mr J. R. Norman in 



IQ.7 As the need for more knowledge of the bionomics of the fish fauna became urgent, Dr Mackintosh 



asked me to prepare this report, working from Gunther's manuscripts. I found this unusually difficult 



because for the first time in my experience it involved work upon data which I had not helped to 



collect Moreover, Gunther had planned the production of five separate papers, and the manuscripts 



were in widely different stages of incompleteness. As a single report was called for I have entirely 



re-written the text myself, retaining Gunther's leading ideas and indicating our indebtedness to him 



so far as I am able. I found it necessary to recalculate all numerical data, using the origmal log books, 



except where the reasons for alterations made by Gunther himself could be traced. Any mistakes in 



this part of the work are my own responsibility. Both Mr Gunther and I have gained much from 



discussion of hydrological results with Dr G. E. R. Deacon, F.R.S., and the brief notes on the 



hydrology of the region presented here owe much to him. 



