44 



Fishery Bulletin 103(1) 



March release 



065 - 

 0.060 - 

 0.055 - 

 0.050 - 

 0.045 - 

 0.040 

 035 



 83-84, n = 24. 7/9 • 8/8 recovery 

 • 84-85. n = 15. 7/29 - 9/2 recovery 



00 



0.5 



3.0 



Late May-June release, June 19— July 19 recovery 



Surface trawl research: maturing fish 



060 - 



0.055 



0.050 - 



0.045 



0.040 



0.035 



030 



— 99-00. n= 78, 6/19-6/25 recovery 

 Y\ 00-01 , n = 50. 9/21 - 9/29 recovery 



05 1.0 1 5 20 



Mean scale growth (mm) 



— i — 



25 



Surface trawl research: juvenile fish 



0.2 0.4 0.6 08 



Mean scale radius (mm, OE = 0) 

 Figure 5 (continued) 



—\ — 

 1.0 



higher between the May and June research cruises 

 (2-3 mm FL/d) than between cruises later in the sum- 

 mer (0.5-1.5 mm FL/d)(Fig. 7C, see also Fig. 6). The 

 concurrent decreases in spacing of circuli at the scale 

 margin and in apparent growth rate of coho salmon in 

 the ocean is consistent with the hypothesis that sea- 

 sonal changes in scale circulus spacing reflect seasonal 

 changes in fish growth rate. 



Additional evidence for decreasing growth rate of 

 maturing coho salmon over the course of the summer 

 comes from FLs of CWT fish in the hook-and-line fish- 

 eries (sport and troll fisheries). Generally, apparent 

 growth rates in FL of maturing coho salmon originat- 

 ing from northern coastal Oregon streams and from 

 both the Oregon and Washington sides of the Columbia 

 river basin were highest from late May to mid-June and 



