3IO - DISCOVERY REPORTS 



At two Stations, however, situated somewhat to the north at the western entrance to the 

 Bransfield Strait (Sts. looo and looi) an appreciable catch was taken. Here the catches 

 amounted to 425 and 93 1 individuals respectively. These two stations lay near the Antarctic 

 continental shelf, where, as already explained, there is upwelling of warm deep water 

 towards the surface, and it may be that at these two stations the Rhincalanus population 

 is carried upwards from its winter level by upwelling warm deep water as was found at 

 the stations in the Southern Drake Passage in the previous season. 



The area of abundance of R. gigas (more than 5000 individuals) during the period 

 from late October to the end of December 1932 was again found in the Drake Passage 

 and the western Scotia Sea (Fig. 14). It occupied that part of the West Wind Drift and 

 Bellingshausen Sea currents in the Drake Passage and between South Georgia and the 

 Falkland Islands. South of the Falklands it embraced all stations at which the average 

 o-ioo-m. temperature was higher than — i-o° C. and lower than 5-0° C. and included 

 stations in the sub-Antarctic zone between the Falklands and South Georgia, and in 

 sub-Antarctic water in the western Drake Passage. In the preceding season the 5000 

 line included stations in the sub-Antarctic zone between the Falklands and South 

 Georgia, but none in the western Drake Passage where the 3° isotherm formed the 

 northern boundary of both the 5000 and 10,000 regions of abundance. It thus does 

 not include Bellingshausen Sea water carrying melting or unmelted pack-ice. In the 

 eastern part of the area of abundance, south-west of South Georgia, the 0° isotherm 

 forms the approximate southern boundary of the region where the catches exceed 2500 

 individuals. 



The stations in the Weddell Sea water east of South Georgia and in the Scotia Sea 

 were taken at the end of November and beginning of December, about a week earlier in 

 the year than the stations in the corresponding position in the previous season (Sts. 761- 

 8). The same comparative scarcity of Rhincalanus can be seen in the colder Weddell Sea 

 water carrying pack-ice (colder than 0° C.) in the season 1932-3 as in the previous year. 

 At only one station (1047) in Weddell Sea water colder than 0° C. was the catch in both 

 nets together in excess of 500 individuals. At nearly all of them it was less than 250 

 individuals. East of South Georgia there is a tongue of Weddell Sea water running 

 northwards and westwards (Fig. 6) similar to that observed in 193 1-2. The lines of 

 equal distribution of Rhincalanus likewise take a similar bend to the west and north 

 before turning east across the South Atlantic. There is also a spreading out of the lines of 

 equal distribution in the Scotia Sea south of South Georgia, where the influence of the 

 Weddell Sea and Bellingshausen Sea currents mingle. 



It is seen from the above that the stations which correspond in date and position in 

 the two seasons (those around South Georgia and in the Scotia Sea) do not show marked 

 differences in the distribution of R. gigas, so that it is perhaps justifiable to attribute those 

 differences in distribution which do appear in the Drake Passage to the earlier date of 

 the stations in these waters in 1932-3 than in 193 1-2. They were taken before the spring 

 ascent to the surface had been completed in the former season but after its completion in 

 the latter. 



