GRAYLING SPAWNING REPORT 



riETHODS 



FISH COLLECTION 



Grayling were captured using either boat mounted electro- 

 fishing gear (either a Buffalo Drift boat or Coleman Crawd£-.d 

 outfitted with a 240 watt gas powered generator connected to a 

 Harvey Leach constructed variable voltage pulsator with mobile 

 anodes) or a backpack elec trof isher (Coeffelt BP-iC) electro- 

 fished in a downstream direction. Sampling began on April 6, in 

 an Br&A of the Big Hols River free of ice, and continued through 

 June 29 (Table 2). Two crews operated during the peak of the 

 spawning run. A total of approximately 54 miles of river and 20 

 miles of tributaries were surveyed during the spawning season. 



Stunned grayling, rainbow trout, and brook trout were 

 captured, except as noted on Table 2. For all captured fish, 

 length was measured to the nearest O.i inch and weights were 

 recorded to the nearest 0.01 pound. 



Sex and state of maturity (immature; mature, but not ripe; 

 ripe; or spent) was recorded for all grayling. Sex >J3termination 

 was based on extrusion of gametes, the ability to feel eggs 

 V'githin the bodv cavity, and the shape of the dorsal fins as 

 documented by Rawson (1950). Ripeness of female grayling was 

 difficult to determine until immediately prior to and during 

 spawning. It was difficult to determine if males were spent 

 because sperm could still be extruded from spent fish. S.Tsaller 

 grayling (fish less than 10.0 inches) v^erEf not checked for sex 

 and state of maturity during the early part of the sampling 

 (prior to April 27). 



Scale samples were removed from grayling and scale impres- 

 sions were made m acetate. Scale samples were later read for 

 age determination. Age interpretation from scale samples up to 

 age IV was believed relatively accurate, while estimation beyond 

 age IV was suspect. Growth interpreted from scales should be 

 reliable because scale samples were obtained in the spring 

 during annulus formation. 



All grayling and rainbow trout longer than 8.0 inches were 

 tagged with a "spaghetti-type" numbered anchor tag. Recaptures 

 of previously tagged fish were noted. Points of capture for 

 grayling were visually noted and recorded m the field. RecoriJed 

 infor-mation included the general hiabitat type and streambed 

 condition where fish were captured and the location by river 

 landmark. These capture locations were later converted to 

 rivermile locations using USGS maps (scale: 1;24,000) and a 

 Rivermile index. 



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