FISHERY BULLETIN: VOL. 87, NO. 4, 1989 



collection method because the nets could be si- 

 multaneously used at different depths and loca- 

 tions. In 1984, fyke nets were also used near the 

 shoreline to provide comparisons of nearshore 

 abundance. These nets could be moved to accom- 

 modate daily fluctuations in river flow. Boat 

 electroshocking and beach seining were also 

 used to monitor nearshore abundance of juvenile 

 salmonids. 



Fyke Net Systems 



Four steel barges were used as fishing plat- 

 forms for the offshore fyke nets (barges 1, 2, 3, 

 and 4; see Figure 2). Two barges were per- 

 manently anchored at opposite shorelines, one 

 in midstream, and the other in midchannel. The 

 dimensions of the two barges were 4.3 by 8.1 m 

 and two were 4.9 by 9.1 m. The platforms and 

 rigging setup were modified after Mains and 

 Smith (1964). A 13 mm (y2-in.) steel cable was 

 used to attach each barge to a 4,500 kg steel 

 anchor (Fig. 3). A drum winch, with a 6 or 8 

 mm windlass cable, was used to raise and lower 

 the net from the back of the barge. Battery- 

 powered windlass winches (Superwinch, Model 

 EW 600^) and hydraulic-powered gypsy hoists 

 (Kolstrand Model 5-24) were used to operate 

 the drum winch on the two shoreline and two 

 midstream stations, respectively. Hand hoists 

 (come-alongs) were used to maintain tension on 



'Reference to trade names does not imply endorsement 

 by the National Marine Fisheries Service, NOAA. 



the windlass cables because the river levels 

 fluctuated daily. 



Each barge fyke net had a 1.5 x 1.5 m opening 

 and was 7 m long. The main body tapered uni- 

 formly to a 20 cm diameter opening at the cod 

 end. All netting was made of 6 mm ('/» in.), 

 heavy-duty, knotless nylon mesh. The net frame 

 was built from streamlined aircraft tubing, 

 measuring 86 x 36 x 1 mm. A General Oceanics 

 Model 2030 flowmeter was attached to the mouth 

 of the net. In 1984, a detachable net constructed 

 of 5 mm (3/16 in.) heavy-duty, knotless nylon 

 mesh was attached to the nylon sleeve on the cod 

 end to retain smaller fish. This net was 1 m long, 

 20 cm across, and had a zippered opening for 

 reaching fish and removing debris. 



Shoreline fyke nets had aim" opening and 

 were 4.5 m long. No wings were used, but an 

 internal fyke was added that decreased the effec- 

 tive mouth size to 0.3 m". All netting was made 

 of 5 mm (3/16 in.), heavy-duty, knotless nylon 

 mesh. The mouth or upstream end of the net was 

 rigged with a weight/float line to keep it vertical. 

 A weight/fioat retrieval line was also attached to 

 the downstream end of the net. 



Fyke Net Sampling Design and Procedure 



The offshore nets were fished from each of the 

 four barges for five 24 h periods each week from 

 26 July through 24 September 1983 and from 23 

 April to 29 June 1984. We also sampled for four 

 days in late July 1984. The spring sampling coin- 

 cided with the expected maximum abundance of 



Drum Winch Hand Hoist 



Gypsy Hoist 

 Barge 



Main 

 Anchor 



250 kg 



Drift 



Anchor 



Figure 3. — Design of the fyke net rigging and anchoring system. 



778 



