450 U. S. BUREAU OF FISHERIES 



fleet may preA'ent the current group from attaining great importance, 

 even if it was originally as numerous as the 1920-1922 broods. 



Savings-gear work. — That there has been wholesale destruction of 

 small fish by the gear now in use by the otter and V-D trawl fleet 

 has long been known. Extensive records collected in 1915 and 1931 

 show that in those years from one-half to two-thirds of the haddock 

 (in numbers) caught by these vessels were too small for commercial 

 use. Similar damage was wrought among the young of other sj^ecies. 

 In the course of a year's time the aggregate number of small fish 

 killed by this method of fishing was enormous. 



A study of the problem was begun in 1931, when the haddock 

 work began, and later tests were made of several types of experi- 

 mental savings gear designed to permit the escape of fish too small 

 for commercial use. The primary object of the experiments was to 

 develop modifications of the commercial gear which would allow the 

 escape of undersized fish without introducing complications that 

 would make the gear unacceptable to the fishermen. 



Except for some preliminary work at Woods Hole and on the 

 Alhatross 11^ the field work has been performed on board commercial 

 vessels. This has made it very desirable to use a method of testing 

 the experimental gear which would interfere with the fishing opera- 

 tions as little as possible. The trouser trawl was found to fit these 

 requirements and gave very satisfactory results. The trouser trawl 

 used consisted of a commercial otter trawl divided up the middle by 

 a partition and with two cod-ends. The gear to be tested was placed 

 on one leg of the trawl and the standard gear on the other. 



The trouser trawl was used for preliminary tests to determine the 

 size and mesh and type of construction necessary to permit the escape 

 of undersized fish with no loss of marketable ones. These results 

 were then utilized in the construction of a commercial savings cod- 

 end. Considerable difficulty was encountered in making this gear 

 sufficiently rugged to compare in durability with the present com- 

 mercial gear on the rough bottom now being fished. A cod-end is 

 being tasted which has so far given satisfactory results. The general 

 design is as follows : 



The bottom of the cod-end is made of the same netting used in the 

 present commercial gear. For the large boats this usualh^ is 4-thread 

 No. 900 manila twine doubled. The mesh measures 3-31/2 inches 

 between knot centers, stretched mesh. The taper on the top of the 

 cod-end and 3 inches of the netting on the lower end of the top is 

 of the same mesh as the bottom. The piece between the taper and 

 lower end section is of 4-thread No. 750 manila twine doubled and 

 5-inch stretched mesh, and is knitted onto the small mesh at the 

 upper and lower ends, taking up two small to one large mesh. The 

 piece of large mesh is made about 20 per cent longer than the cor- 

 responding section on the bottom of the cod-end. This gives ap- 

 proximately the same area of netting on top and bottom and helps to 

 keep the large top mesh open when there is anything in the cod-end. 

 The small-meshed piece at the lower end of the cod-end top also 

 gives additional strength to this section, where the chief strain 

 comes in swinging the catch inboard; and if one strand is cut, no 

 appreciable amount of the catch is lost. 



