SEA-FISHERIES LABORATORY. 235 



REPORT ON THE PLANKTON OF THE PERIODIC 

 CRUISES OF THE "JAMES FLETCHER" IN 

 1912-13. 



By W. Riddell, M.A. 



The plankton observations made on the " James 

 Fletcher " during the year may be divided into two series. 

 There are first the routine vertical hauls made with the 

 Nansen closing net, 35 cm. in diameter, of number 

 20 silk. These hauls are made regularly on the hydro- 

 graphic cruises at the following Stations; (see chart on 

 p. 234) ; at Stations 5, 6 and 7 on all cruises, and at 

 Station 14 on the quarterly cruises The net is lowered 

 to 20 fathoms and then hauled vertically to the surface. 

 There are also a considerable number of horizontal hauls 

 made either with the ordinary surface tow-net of book- 

 muslin, or with a shear-net of embroidery canvas. These 

 have been taken at various places throughout the district. 



Nansen Net Observations. 



Unfortunately we have not as complete a series of 

 these as we had wished for. Owing to various causes 

 involved in the starting of a new scheme, and especially 

 to unavoidable delay in obtaining the new nets from the 

 manufacturers, we were not able to use a standard net 

 until the second quarterly cruise, which was carried out 

 during the end of July and beginning of August. 

 Various temporary substitutes were used on the earlier 

 cruises, but these, while giving some indication of the 

 nature of the plankton present, cannot be used for 

 comparison with the later hauls. Further, the weather 

 during the cruise at the beginning of February, 1913, 

 was so bad that we were unable to use our nets. 



