584 FISHING NETS, WITH SPECIAL KEFEKENCE TO THE OTTER-TKAWL. 



generally held by trawlers, and indicated by the calculations of 

 Garslang* and Fulton,f that the otter-trawl catches about 30 per 

 cent, more round fish than the beam-trawl, but the same amount of 

 flat fish. Whatever reliance may be placed on these conclusions, and 

 they are admittedly based on indirect evidence, it is certain that the 

 otter-trawl is not so adaptable for catching flat-fish as the beam-trawl. 

 The high rate of speed which is necessary in the former case in order 

 to keep the mouth of the net open, detracts from its power of catching 

 flat-fish. If the speed is reduced the spread of the mouth will fall 

 below that of the beam-trawl, and the same thing would occur if 

 any extra weight, such as an iron chain or dangles, were attached 

 to the foot-rope as in the beam-trawl, in order to stir up the fish. 

 With respect to size of mesh, also, the otter-trawl is at a great 

 disadvantage in comparison with the beam-trawl. A smaller mesh 

 means less speed, and this, as shown, distinctly affects the fishing 

 capacity of the former, and that adversely, whereas if it affects the 

 beam-trawl it is favourably. The head of the net in the latter is 

 always a fixed height from the ground, and the reduced speed that 

 the smaller mesh demands does not affect the spread. 



There can be no doubt, therefore, that for certain purposes the beam- 

 trawl is preferable to the otter, and more especially for small flat-fish. 

 Petersen's trawl, for example, is exceedingly well adapted for this 

 purpose, but it would fish better, I think, and with less trouble, if 

 a beam were attached to it. Its utmost spread appears to be 16 ft., 

 but in practice it is probably less, whereas if it were converted into 

 a beam-trawl its spread would be constant and assured. The small 

 size of its mesh — less than 1 in. — makes it comparable, not to an 

 otter-trawl or ordinary beam-trawl, but to the well-known shrimp- 

 trawl. In the latter the beam may be of any length between 8 ft. and 

 24 ft., and its height from 15 in. to 2|- ft. The size of mesh varies 

 from 1 in. down to I in., and in formation the net may be exactly 

 as the ordinary beam-trawl. In place of a wooden beam, however, 

 a hollow iron pipe is better. For deep-sea work in depths greater 

 than 20 fathoms Agassiz' modification of the shrimp-trawl is very 

 useful, because it is immaterial which side it falls on.^: 



The average speed at which the otter- trawl is towed over the ground 

 is 2^ knots per hour, the beam-trawl 2 knots, and the shrimp-trawl 



* Journ. M. B. A., vol. vi. p. 50. t Loc. ciL, pp. 122-5. 



+ Bull. U.S. Fish Covimission, xvi., 1896, p. 357. Petersen (loc. cit., p. 6) would have 

 it that the Americans are iuclined to return to the single form of shrimp-trawl, but this 

 does not seem warranted. Petersen has slightly misquoted the words of Tanner in the 

 Bulletin cited. According to Tanner, " e.xperts " are able to land the ordinary shrimp-trawl 

 right side up in deep water ; Petersen has it " investigators." There is here a distinction 

 as well as a difference. 



