SEA-FISHERIES LABORATORY. 195 



The net A (which may be called the weight-net) is of 

 use as having traversed a wider range, to 10 fathoms, 

 so as to sample all the water above the zone traversed by 

 the vertical nets, and it frequently, and in fact usually, 

 obtained a larger gathering and showed a greater variety 

 of organisms than either the deeper, closing (vertical) or 

 the open surface nets. 



On some occasions, at the " along-shore " stations 

 (e.g., 2 miles off Bradda Head) hauls were taken with a 

 new " shear-net " made on the principle of the Heligoland 

 " Scherbrutnetz " (Conseil International — Rajiports et 

 Proces-verb., vol. ii, p. 62, 1904). This was used as a 

 mid-water net — being lowered to a depth of 5 to 10 

 fathoms, where, through the action of the shearing plate, 

 placed like a vertical otter-board, it remained even when 

 the ship went ahead at a moderate speed, and so formed 

 a most efficient instrument of capture in waters where the 

 ordinary net cannot be towed. The mouth measured nine 

 feet in circumference, the net was over ten feet in length, 

 and being formed of rather coarse mesh caught quantities 

 of the larger organisms of the plankton such as Sagitta, 

 Medusae, Ctenophora, Zoeas, the larger Copepoda and 

 some young fishes. 



The variation in the bulk of the catch on different 

 days with the same net, used so far as was possible 

 under the same conditions, was very remarkable. The 

 accompanying diagram shows graphically the range in 

 quantity of the total catches with each kind of net during 

 April, 1907. The Nansen net catches ranged in quantity 

 from 0*5 c.c. to 164 c.c, the Petersen-Hensen from 

 0'5 c.c. to 64*5 cc, the weighted open tow-net from 

 5*5 c.c. to 41 c.c, the surface open tow-nets from 1 c.c. to 

 42'5 c.c, and the shear net from 11 cc to 78'5 c.c. The 

 black columns in the diagram (fig. 2) are drawn to scale, 



