SEA-FISHERIES LABORATORY. 103 



T to 9 fathoms, the duration and length of the drags were 

 identical, and all three were made dragging with the 

 stream. Nevertheless, the number of plaice taken varied 

 from 51 to 438, the dabs from 10 to 68, and the ray from 

 26 to 10. The fifth, haul was made dragging in towards 

 shallow water. The fourth and sixth hauls were shorter 

 than the others, being of one and three-quarters and two 

 miles length respectively. They differed, however, to an 

 extent which is not accounted for by their difference in 

 length, as the fourth yielded only 64 plaice, while 197 

 were obtained in the sixth. The sixth haul, too, was 

 made in the dark when, according to general experience, 

 plaice are more difficult to catch in the trawl net. 



There is a general similarity between the results of 

 the first three hauls obtained on this occasion and those 

 obtained on October 21st, 1902 (see last year's Eeport, p. 

 85). The positions, states of the tide and lengths of drag 

 are very approximately the same in each series. Both 

 the first hauls, dragging north from Drummore yielded 

 poor catches (14 and 68 plaice, respectively), the second 

 hauls gave much better results (438 and 157 plaice), while 

 the third were again poor (17 and 51). 



The results obtained on the present occasion confirm 

 then those obtained in 1902, that is, that a trifling 

 difference in position of the ground dragged over may 

 correspond with very remarkable differences in the volume 

 of the catches. This, indeed, is well known to fishermen, 

 but it is a factor which has not been sufficiently recog- 

 nised in statistical trawling operations, where it has been 

 generally assumed that the distribution of fish on a large 

 area is fairly constant. 

 Sizes of the plaice obtained. 



The main object of the trawling operations was to 

 obtain mature plaice, and in each haul all the fish of over 



