THE OLDER STAGES 133 



There is little doubt then that many fishes do feed more or less heavily on the krill. Some of them 

 (e.g. Notothevia rossii) are known to be exceedingly abundant in certain places, but there is no knowing 

 what quantities of krill-eating pelagic fish may exist in the vast area of the Antarctic seas in which this 

 euphausian is known to range, for as yet no suitable method has been devised for quantitative sampling 

 of the larger and more active pelagic animals. For all we know there may be vast numbers of oceanic 

 fishes subsisting on the krill, devouring it on a scale far greater than our existing knowledge permits us 

 to believe. 



In his Living Resources of the Sea Walford (1958) surprisingly seems to regard the Antarctic fish 

 population as playing only a minor part among the predators of the krill as a whole. He writes : 



One of the most striking features in the economy of life in the antarctic seas is that few fishes have the form and 

 swimming powers to utilize krill (planktonic crustaceans) as a source of food. The evolution of pelagic types of 

 nototheniid fishes has been limited, and it is the warm-blooded animals, the whalebone whales, crab-eater seals, and 

 penguins, which make most use of the krill. In oceanic circumpolar waters, a number of small bathypelagic fishes 

 feed particularly on krill and are often to be found with the latter in the stomachs of whalebone whales.^ These 

 fishes, however, would hardly repay commercial exploitation. 



Obviously, however, the coastal and exceedingly numerous Notothenia rossii has both the form and 

 speed to capture and devour these large euphausians on an enormous scale and there seems little 

 reason to doubt that other coastal or inshore forms are equally well equipped. As for the other krill- 

 eaters, both coastal and pelagic, time has yet to show that they are really so scarce as our sluggish 

 bottom apparatus and plankton nets reveal them to be. As Marshall (195 1) has said of the pelagic 

 forms, ' it is highly likely that they are much more numerous than is indicated by collecting gear '. 

 How abundant, and evidently closely packed, they might well in fact be, is suggested in the following 

 passage from Worsley (1959) in his vivid description of the escape of Shackleton's boats from the ice 

 of the Weddell Sea: 'Lying about in the slush and on the "pancakes" were countless thousands of 

 dead fish, some of which were eight inches long. They had been caught and frozen by the sudden 

 freezing of the sea. They looked like splashes and bars of silver glistening in the sun. The petrels 

 and Cape pigeons were enjoying an unusual feast. Like the birds, we would have relished a splendid 

 meal of fish, but we dared not waste time gathering them '. 



Nordenskjold (1905) also reports a concentration of dead fish floating at the surface in this locality, 

 and in January 191 2 (Filchner, 1922) the ' Deutschland ' encountered fish in great abundance among 

 the open floes of the East Wind drift in 67° 27' S, 26° 16' W. 



The silvery colour and bar-like appearance of Worsley's fish recall Dollo's (1908) original descrip- 

 tion of Notolepis coatsi, itself (Marshall, 1955) a voracious krill-eater, and if it was in fact this species 

 he saw then one can well imagine it, growing as it does (Marshall, 1954) to a length of at least 2 ft., 

 as a major predator of the krill, especially if, as this instance of mass mortality suggests, it congregates 

 densely in shoals. Pelagic fish larvae too are sometimes encountered in great concentration. I saw 

 them, in clouds, swarming near the Ross Ice Barrier in January 1936. 



Hodgson (1905) refers to the wealth of fishes in McMurdo Sound, noting that they were abundant 

 all the year round and that the hundreds of Weddell seals in this locality lived almost exclusively on 

 them. He mentions one very large Nototheniid weighing 39 lb., 3 ft. 10 in. long, with a girth, just 

 behind the pectoral fins, of just over 2 ft. 



The foregoing survey probably includes most of the larger animals that feed exclusively or very sub- 

 stantially on the krill. But there may be others, perhaps many others, especially among the fishes 

 and (p. 134, note 2) squid. It would not be complete, however, without mentioning the Weddell seal, 

 the Leopard seal, the Ross seal, the Emperor penguin and the Antarctic shag, all of which have been 



1 Suggesting strongly, however (p. 168), that they were at least not bathypelagic when swallowed. 



