255 



GENERAL ACCOUNT OF THE FISH FAUNA 

 beds of kelp {Macrocystis, Durvillea, etc.) may extend out to 30 fm. and render any form of fishing 

 difficult, though they certainly harbour many species of fish. 



The trawl seems an adequate sampling instrument within the limits set by the mesh used. Hicklmg 

 (i933' PP- I ^-^9) ^^^ g^'^^^ adequate demonstration of this, and our results with a closely allied species 

 of hake (pp. 284-9) conform with his as closely as could reasonably be expected. Faulty hauls cannot 

 prove absence or relative abundance, but have helped to prove presence of certain species on some 

 occasions. The trawl cannot provide adequate data for pelagic species such as herring, or very small 

 species such as some Zoarcidae. Immature specimens of some of the larger, more important species 

 also escape through the meshes. This loss is most serious with the more slender forms, such as very 

 young hake (especially males), immature Macrurontis, Mkromezistim and Genypterus. The fine- 

 meshed nets attached to the back of the trawl caught enough of these to enable us to outline their 

 probable distribution, but do not provide comparable quantitative data. Provided that these limita- 

 tions are borne in mind. Table 2, which gives the total numbers of the species in ' Trawl + accessory 

 nets', and their frequency of occurrence, helps to extend the outline of our general picture of the fish 

 fauna begun by the first table. 



The fish fauna of the Patagonian shelf is not rich in species, as the full list in Table i shows. In a 

 preliminary account of the trawling surveys,^ Gunther pointed out that it is less than one-third of the 

 strength of the British list, and nearly twice as many species occur in the Gulf of Maine (Bigelow and 

 Welsh 1925) Apart from the numbers of species, there are big qualitative differences from the types 

 of fish' faunas known from other parts of the world. The marked predominance of the percoid group 

 Nototheniiformes, with four families, seven genera and twenty-one species from the area of the surveys, 

 and relatively large number of Zoarcidae with eleven species representing eight genera, are a most 

 peculiar feature. Among elasmobranchs Rajidae show many species and remarkable diversity for an 

 area where nearly all the known changes in environmental conditions are gradual. Dogfish are not 

 common on the shelf, and the numbers of species of true codfishes (Gadidae) is small; in these 

 features we see a great contrast to the fish faunas of northern Europe and of the New England states. 

 Table 3 showing the relative strengths of some of the important groups in British seas, on the Pata- 

 gonian shelf and in the Gulf of Maine, summarizes these points. The comparison between British 

 and Patagonian fish faunas was first made by Gunther in the preliminary account mentioned above, 

 and I have abstracted figures from Bigelow and Welsh (1925) for the Gulf of Maine to make the 

 comparison wider. 



Table 3. Relative proportions of certain taxonomic groups in British 

 seas, on the Patagonian shelf and in the Gulf of Maine 



No. of spp. 



Rajidae 

 Percomorphi 



Gadidae 

 Heterosomata 



British seas 



350 



5% .. 

 31%: No Nototheniiformes 



Zoarcidae i sp. 



8% 



Patagonian shelf 



95 



10% 

 48%: Nototheniiformes 21 spp. 

 Zoarcidae 11 spp. 



3% 

 5% 



Gulf of Maine 



173 



3*°' 



27%: No Nototheniiformes 

 Zoarcidae 3 spp. 



7% 



-710/ 



72 /o 



The Nototheniiformes are, of course, an essentially southern group, but it has further to be noted 

 that most of the Patagonian species are distinct from the Antarctic ones; and the number of species 

 comln to other sub^Antarcdc localities, such as the Antipodes, is small. The relations between the 



1 'A Fishery Survey of the Patagonian Continental Shelf read before Section D of the British Association, July 1938- 



