234 DISCOVERY REPORTS 



THE SECOND SURVEY 



The second trawling survey was carried out in the winter (June and July, 1928). Mr D. Dilwyn John 

 was in charge of the scientific work and was assisted by Mr J. W. S. Marr. This survey was planned 

 as a continuation of the first, with additional observations designed to discover the conditions to be 

 found along the edge of the shelf in depths below 200 m. Routine methods at the trawling stations 

 were the same as those followed during the first survey, with the addition of extra water sampling 

 before as well as after the trawling. At this time the ship was (unavoidably) without an experienced 

 trawler hand, and Mr John remarked that this led to much difficulty until the necessary experience 

 was acquired. Much foul ground was encountered so that much time was spent in mending nets. 

 The weather was often atrocious, and some minor breakdowns hindered operations still further, so 

 that the ship. did well to complete a rather larger programme than before (Fig. i b) in about the same 

 time. Material was dealt with as in 1927, and a large representative collection of bottom samples and 

 of the fauna was made. 



On this survey the numbers of hake taken were small (1071 in all) and good hauls few, but it is 

 probable that they were present nearby in greater abundance, as the following considerations show. 

 The best catches were obtained on the edge of the shelf in depths of 200-300 m., on a line running 

 north to a point some 300 miles north of the Falkland Islands. Later the same area was disappointing. 

 The bottom was of clean, fine, dark green sand. On the coarse brown sand, pebbles, and shells, of the 

 shallower waters of the shelf, very few hake were taken in the north, and fewer or none to the south. 

 In the trough of relatively deep water to the west of the Falkland Islands, two very moderate catches 

 were obtained. No hake were taken on the shelly bottom with heavy invertebrate fauna to the south 

 and south-west of the Falkland Islands. 



Comparing these results with those of the previous autumnal survey, when most hake had been 

 captured on the shelf to the north and west of the Falkland Islands, it was seen that the different 

 distribution observed in winter would agree with an offshore migration. Such a seasonal movement, 

 connected with the sexual rhythm, was already known to occur in the closely allied European species, 

 and by analogy John concluded that the Patagonian hake were summer spawners also. The data on 

 condition of the gonads, though not entirely satisfactory, were compatible with such a view. The 

 comparatively good catches in shallower water of March and April 1927 would thus be accounted for 

 by closer proximity to the spawning season, and the poor hauls of June and July 1928 mainly by 

 fishing ' out of season '. 



It was known that European hake were caught most readily when concentrated for spawning in 

 relatively shallow water, and that deep-sea trawlers from British ports followed the ' seasons ' south- 

 wards, sometimes as far as the Moroccan coast. Also some of the British boats were already working 

 ' over the edge ', in far deeper water than any in which large-scale trawling had previously been carried 

 out, in order to keep the market going during the off-season. Hence John's decision to work extra 

 stations along the edge of the shelf. The fact that these were only moderately successful was almost 

 certainly due to the steepness of the slope (far greater than that off the west coast of the British Isles) 

 which left a very small area of moderately deep water in which fishing was possible. John concluded 

 that a commercial fishery would have to follow the spawning fish throughout the year, and that that 

 would mean going farther afield to the northward than the first two surveys had proceeded. Sub- 

 sequent work fully substantiates this view. 



The most important result of the second survey lay in this recognition of the fact that Patagonian 

 hake would be found to move with the seasons in much the same way as their better known European 

 relatives (allowing for the reversal of the seasons in the southern hemisphere). 



