132 DISCOVERY REPORTS 



Matthews (1951) also refers to the local abundance of A^. rossii and the massive impact of its assault 

 on the krill in these island waters : ' In about twenty minutes we came to a place near a small iceberg 

 where the birds were gathered in their tens of thousands, and the krill was so dense near the surface 

 that it made the water quite soupy. And there were the fish, about two fathoms down, thicker than 

 salmon under Galway bridge, so closely packed that it looked like a solid bottom of huge pebbles 

 just under our keel '. He adds that the fish were two to three feet long, ' splendid great bull-nosed 

 fellows', and that they were gobbling up the krill as hard as they could, their stomachs all being 

 crammed with it. 



Olsen (1954) states that the adults of this species feed almost exclusively on E. superba and calls 

 attention to the immense numbers of them that frequent the continental shelf on the east side of the 

 island from Gierke Rocks in the south to Willis Island in the north. ' As soon as it is light enough in 

 the morning', he writes, 'the "sea-fish"^ begins to hunt the "krill" at the surface, where it is found 

 gambolling about. In good weather it was possible therefore on light days to see shoals of fish as far 

 as the eye could reach, but when the sun went down, all was still again '. 



While all the fishes I have mentioned are either shallow-water coastal forms or, if oceanic, 

 inhabitants of the Antarctic surface layer, ^ there is evidence that much deeper living species, even those 

 commonly regarded as bathypelagic, may occasionally come to the surface to prey upon the krill. In 

 his report to the Discovery Committee on the work of R.R.S. 'William Scoresby' in January and 

 February 193 1 Dr N. A. Mackintosh records at Station WS 540 'an eel-shaped Stomiatoid fish, with 

 brilliant luminous organs and silvery scales ' which was feeding on krill close to the surface and could 

 plainly be seen by the light of a cargo cluster. In the Note and Sketch log for that period Gunther gives 

 a vivid description of this incident which I quote (see also Clarke, 1950; Hardy, 1956) exactly as that 

 brilliant natural observer recorded it: 



In the midst of a swarm of krill which had drifted round the ship, an eel-shaped silvery fish 9-12 inches in length 

 was observed by the light of a cargo cluster. 



From a pair of luminous organs in the orbital region, the fish emitted a beam of varying intensity of strong blue 

 light which shone directly forwards for a distance of about two feet. The fish had the habit of lurking at a depth of 

 2-6 feet below the surface, poised at an angle of about 3 5 "-40° from the horizontal, head up — this gave the beam 

 an upward tilt : occasionally the fish swam round and with quick action snapped at the cloud of krill above it. 



In its manner of lurking and of snapping prey it was semblative of the freshwater Pike. From the anal region was 

 seen to trail a length of brown substance which it was supposed might have been either genital or faecal product. 



Efforts to catch the fish with a hand net failed owing to the drifting away from the ship of the krill swarm. 



The supple silver of the fish, the parallel beams of blue which emanated from its forehead, and by the Hght of 

 the cluster other animals seen swarming at the surface — particularly Ctenophores with iridescent combplates which 

 in waving bands gleamed the spectrum — combined to give an effect of consummate wonder and beauty. 



This record is of special interest as it appears to be the first notice of the existence of Stomiatoid 

 fishes in Antarctic waters. Although the fish could not be captured there is little doubt that those who 

 saw it assigned it to the correct group, for Mr Marshall tells me that among the undescribed collections 

 of Discovery fishes in the Natural History Museum there is a specimen of the genus Melanostomias 

 taken at a depth of 450-270 m. at Station 1356 in 60° 12-8' S, 19° 37-5' E. 



Since the krill themselves (p. 168) are not bathypelagic, but tend to cleave, especially at night, very 

 much to the surface zone, Notolepis coatsi would appear to be another bathypalegic form, if it is in fact 

 a bathypelagic form,^ that comes up to the surface to feed. 



1 That is, as distinct from the young kelp-living N. rossii of the South Georgian fjords. 



* Notolepis coatsi perhaps excepted (but see p. 155, note i). 



^ But it may not be. Referring to its frequent occurrence in whales' stomachs Nemoto (1959) states that the fish has been 

 seen chasing E. superba on the surface and since this evidently was a daylight observation it suggests that it need not necessarily 

 be a deep dweller that comes up to the surface at night. 



