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replenishment on the Humptulips and other southern Olympic rivers. 



Three kinds of gravel mining have been used in the Basin: in-channel 

 excavation; bar scalping; and off-channel pit excavation. Although in-channel 

 excavation is now prohibited, the other two types continue. Two main fishery 

 issues remain unsettled. First, is the annual gravel harvest limit low enough 

 to ensure against downcutting the river bed and depleting the gravel available 

 for fish in coming years? Second, will present operations destabilize the 

 mined bars or cause channel shifts that make the gravel less suitable for 

 spawning and incubating salmon id eggs? 



SEDIMENTATION 



Sedimentation occurs in the form of (1) siltation, that is, deposition of mud 

 and silt carried by the stream and then deposited as flows recede, and (2) 

 bedload aggradation, that is, excessive addition of sand, gravel and boulders 

 which the stream pushes along its bed. Siltation can smother gravel beds, 

 making them unsuitable for fish spawning or incubation. It can also decrease 

 production of aquatic insects, upon which fish depend for food. Bedload 

 aggradation causes the channel to widen and shift position more than normal, 

 thus potentially drying incubating eggs and rearing fry. There are five 

 sources of sedimentation: timber-related activities; urbanization; flushing of 

 sediments from behind dams; runoff from tilled farmlands; and natural slope 

 failures. All but the last have already been discussed. 



Natural slope failure is presently the most obvious source of sedimentation. 

 For example, recent movement of a chronically unstable slope on the North Fork 

 Newaukum created a landslide that entered the stream, and raised the suspended 

 solids in the water to the point that it was not suitable for municipal use 

 for many months (Ciolli, City of Chehalis, pers. comm. ) . 



EFFECTS OF FISHING 



Every fishery has the potential to overfish the wild stock so that it fails to 

 meet its escapement goal. Bycatch, marine interception, terminal harvest, and 

 poaching singly or together could theoretically contribute to overfishing. 

 State and tribal fishery managers make every effort to avoid overharvest in 

 the terminal area. 



Bycatch 



Bycatch is the incidental catch of salmon and steelhead in a fishery that 

 targets another species. Many workers have studied bycatch of North American 

 salmonids in the Japanese squid fishery (Myers st ml. 1990; Burgner et al . 

 1992; Ishida and Ogura 1991; Jfatsu and Hayase 1991), the Alaskan groundfish 

 trawl fishery (Myers and Rogers 1988), and the Japanese salmon gillnet fishery 

 (Harris 1968; Burgner et «i. 1992), and, despite emotional arguments to the 

 contrary, high seas bycatch has not been shown to have damaged Washington 

 stocks (Dr. Kate Myers, University of Washington, pers. comm.). 



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