DESCRIPTION OF CRUISES 23 



After the arrival of the ' Discovery ' the first main survey of the waters round South 

 Georgia was carried out by the two ships during December and January. It was decided 

 first to cover the area off the north-east side of the island in which most of the whaling 

 takes place. To do this five lines of "full routine" stations were planned (see Fig. 13): 

 line A running north-west of Bird Island, the most northerly point of South Georgia ; 

 line B due north from Prince Olaf Light; line C north-east from Larsen Point; line D 

 due east of Cape Vakop ; and line E south-east from Cooper Island off the southern end 

 of South Georgia. The stations along each line were arranged at 10-mile intervals, the 

 first being at a point 5 miles from the coast and the last when soundings of 1000 m. or 

 more were met with, each line being limited to six stations. The stations have their 

 proper sequence numbers, e.g. 124, 125, 126, etc., or WS 26, 27, 28, etc., according to 

 whether they were taken by the 'Discovery' or 'William Scoresby', respectively; but 

 it will be convenient in discussing the results of the survey to refer to them also as 

 stations A1.A2.A3, . . . , B 1, B 2, B 3, ..., etc., according to the line to which they 

 belong and numbering out from the coast. Stations were also arranged in intermediate 

 positions between the lines: AB, BC 1 and BC 2, CD 1 and CD 2, and DE between the 

 lines indicated by the lettering. This programme, which was shared between the two 

 ships working simultaneously and continuously, was completed within a week, from 

 December 17 to 23. 



After making a rapid examination of the material collected, four pieces of work 

 appeared necessary to complete the survey : 



(i) To carry out similar lines of stations on the other side of the island, to the west 

 and south-west, with intermediate stations to complete the picture of conditions around 

 the island. 



(ii) To continue line B, at the end of which quantities of krill (Euphausia superba) had 

 been taken over deep water, to see how far the krill extends beyond the coastal slopes. 



(iii) To carry out one or more continuous series of consecutively towed nets to 

 determine the frequency, size and density of the patches of krill and other large or- 

 ganisms; this patchiness was indicated by tow-nettings taken at previous stations. This 

 was considered of great importance in that it would form a "control" to determine 

 the reliance that could be placed upon observations made by a single net. E. superba is 

 too large to be satisfactorily recorded on the Continuous Plankton Recorder. 



(iv) To take current measurements at each end of the island to determine the rate 

 of the drift of the water carrying the plankton, an indication of movement about the 

 island having been suggested by the preliminary examination of the material. 



This programme was delayed by weather and other causes, but was completed 

 between January 6 and 23, except that only one set of current measurements at the 

 north-west end of the island could be taken. Two lines of full routine stations were taken : 

 line F running S 15 W from Pickersgill Island with F 1 between this island and the 

 mainland, and line G running S 75 W from Cape Nunez. Line G was extended to 

 G 7, stations G 1 to G 6 being all in shallow water. Intermediate stations were made 

 at EF, FG and GA. The B line was extended to B 9 by taking horizontal routine 



1- ■ 



