268 



DISCOVERY REPORTS 



80- 



> 



liJ 60 



< 



t; 40 



20 



Fig. 14. A. 



(<2O0 



Seasonal variation in total abundance of Raja brachyiirops 'over the edge' (> 200 m ^ 

 m.) white; also seasonal variation in its frequency of occurrence B on the shelf, and 



black, and on the shelf 

 C 'over the edge'. 



Season 



Spring 

 Summer 

 Autumn 

 Winter 



Spring 

 Summer 

 Autumn 

 Winter 



Table 5. Full data relating to Raja brachyurops /)/o«g^ in Fig. 14 



On the shelf, depths less than 200 m. 



No. of 

 individuals 



6 

 62 



74 



17 



% of total 



caught in 



each season 



60 

 95 

 97 

 14 



Over the edge, depths more than 200 m. 



No. of 

 individuals 



No. of 

 hauls 



14 

 65 

 42 

 17 



No. 

 positive 



3 



17 

 18 



3 



positive 



21-4 

 26-2 

 42-9 

 17-6 



4 



3 



2 



106 



% of total 



caught in 



each season 



40 

 5 

 3 



86 



No. of 

 hauls 



2 

 10 



8 

 13 



No. 

 positive 



positive 



SO 

 10 



12-5 



38-5 



Separate depth-frequency polygons of the type used for summarizing the main features of depth 

 dj nbutton of all elasmobranchs may also be plotted for R. brachyr.ops at each season, as m Fig '5 

 This presents the evidence of seasonal migration even more clearly ^' 



Very good evidence that the young of R. brachyurops are hatched on the shelf can be obtained bv 

 considering our records of captures of minute post-embryos and yearlings less than zo cm wide' 

 The r seasonal distribution also is so circumscribed as to establish the approximate hatching peT od 

 and they are accordingly tabulated in full (Table 6) naicning period, 



3oMaThaLTMlv'lltt' 't '"" V"' T'"''''^'' ^^^ ^"^^" ^^^^^^^^ -- -"g^^ between 



xcfp ons I'o cm Id f T'n . ' '""'"' observations were made at other seasons. Of the 



exceptions, the 9 cm. individual in October was presumably a late-hatched survivor of the previous 



