FISHES FKOM NORTHEASTERN PACIFIC — CHAPMAN 503 



100, 200, and 300 meters; the "B" nets at 400, 500, and 600 meters; 

 and the "C" nets at 700, 800, and 900 meters. Collections at 344 of 

 the stations were of this type. At times other nets were added below 

 when the depth of the water permitted. At other tunes, when the 

 boat was over shallower w^ater, the bottom net, and sometimes also 

 the "B" nets, were omitted. When towing over shallow water, the 

 depth intervals of the nets were often altered to conform with the con- 

 tour of the bottom. The time that they were towed at each depth 

 was then nearly always one hour. Some vertical hauls were also 

 made both with the regular open nets and with closing nets. This 

 type of haul yielded very few fish. 



All the "standard" hauls were made with 1-meter nets of the same 

 type. These were nets, 1 meter in diameter at the mouth, made of 

 silk 24 meshes to the inch in the cone and 14 to the inch in the cylinder. 

 This type of net was used as the standard for the winter work because 

 of the ease with which it could be handled in stormy weather and its 

 relative efficiency. In smooth weather hauls were sometimes made 

 with nets 2 meters in diameter at the mouth made of silk grit gauze, 

 and Petersen Young fish trawls constructed out of quarter-inch mesh 

 cotton netting. These latter were sometimes hauled at depths as 

 great as 1,500 meters and caught many deep-sea fishes. Another 

 type of net, the Danish trawl, was used extensively in 1931. It was 

 a cone of "stramin" cloth hung on a hoop about 7 feet in diameter. 

 It also yielded many fish. 



DEPTH OF CAPTURE 



Because of the fact that the hauls were made with open nets, it is 

 not possible to determine accurately the depth at which any individual 

 specimen was captured, for presumably the nets fished both on the 

 way down and up. The bottom nets, therefore, had an opportunity 

 to catch fish in the surface and intermediate levels as weU as at the 

 depths they were supposed to fish. This would not have been the 

 case had closing nets worked satisfactorily. Unfortunately, the clos- 

 ing nets were unsuccessful as captors of adult fish. Furthermore, 

 although a heavy weight was attached to the end of the wire, it did 

 not hang straight down in the water. The IFC has used 85 percent of 

 the length of wire out as an approximation of the depth at which the 

 net was fishing. An effort was made to keep the cable at a constant 

 angle, but in the stormy weather and strong tidal currents prevalent 

 at times in the area covered it was impossible always to do so. It 

 turned out, however, that an approximation could be made of the ver- 

 tical distribution of several species because, although an individual 

 would perhaps be caught during the short period of raising or lowering, 

 it was safe to assume that numbers were taken only during the actual 



