312 DISCOVERY REPORTS 



The males do not show any correlation between increase in length and increase in liability to 

 infection. The smallest length class showed the highest percentage infection, which was also con- 

 siderably higher than that of females of the same length. I think this discrepancy is in some way 

 bound up with the marked differences between the sexes that became apparent in the study of the 

 general bionomics of this fish. Apart from the size difference, and almost certainly slower later growth 

 rate, male M. hiibbsi reach maturity at a much smaller length than females, they seem less given to 

 shoaling during the ' off' season, and do not migrate so far as the older females. All these factors may 

 influence their chances of infection by Lernaeoceridae. 



Macruronus magellanicus Lonnberg 



This is a long, slender fish, with close superficial resemblances to the Macruridae, with which it 

 was formerly classified. Norman (1937, p. 49) has shown, on osteological grounds, that it should be 

 placed in the family Merlucciidae. The tail, tapering to a point and without a separate caudal fin, is 

 the most noticeable point of similarity to the macrurids, but Macruronus lacks their projecting snout, 

 and its distribution and habits are markedly different. Macruronus is found in numbers only on the 

 shelf, in relatively shallow water during at least nine months of the year, whereas the macrurids are 

 essentially a deep-water group inhabiting the slope beyond the shelf edge and even greater depths. 

 The coloration of Macruronus reflects this difference in habitat. In Plate XVI a water-colour sketch of 

 a living specimen taken at St. WS99, by E. R. Gunther, is reproduced. At an earlier station he had 

 described its coloration thus : ' laterally a pale lustrous blue, becoming more intense dorsally into 

 tones of sapphire and turquoise, ventrally losing colour becoming silvery white.' A colour pattern 

 such as this is normally characteristic of mid-water fishes inhabiting moderate depths over a well- 

 illuminated sandy bottom, and this would apply fairly to that part of the plain of the shelf where we 

 found the smaller individuals most abundant. 



It IS interesting to note that the correct taxonomic position of Macruronus is reflected in the local 

 Spanish-American name ' Merluza de cola ' which Norman (loc. cit.) states is applied to it. This might 

 be freely translated into 'long-tailed hake' with advantage, for English-speaking fishermen tend to 

 apply the names ' rat-fish ' or ' rat-tail ' to anything remotely resembling a macrurid, consequently 

 confusmg them with fishes as gsnetically remote as chimaerids in some parts of the world. 



M. magellanicus is the second most important fish of the Patagonian Continental Shelf. In our 

 catches it was outnumbered only by Notothenia ramsayi, but although slightly more numerous than 

 hake in the aggregate it was less widely distributed, a few exceptionally rich hauls augmenting the 

 total unduly. A much more slender fish than the hake, it is about half as heavy at a given length, and 

 a larger proportion of the smaller individuals escaped through our normal cod-end mesh. There are 

 numerous references in our rough logs to 'Macruronus seen escaping'. In the eighty-six summer 

 hauls of the third survey, for which roughly comparable weight data are available, Macruronus yielded 

 29-5% by weight of the total fish taken (rubbish excluded) as against the 47-3% of hake. The relation 

 to other less important categories can be seen from the tables in the concluding section of this report. 

 Macruronus was the most important species in the southern region, where, as we have already seen, 

 the hake diminished greatly in numbers. Of the weight of fish caught here, Macruronus provided 



4^2 % • 



M. magellanicus is most excellent eating. In the third (unpublished) scientific report' on the work 

 of the ' William Scoresby ' Dr Mackintosh wrote : ' It is generally agreed that Macruronus is superior 

 to any of the other common fishes. The flesh is reasonably firm and free from too many small bones.' 



