214 



DRAFT 



"TTie U.S. Fish and Wildlife Service (1983) uses a shaker mortality rate 

 for Klamath River fall chinook...of 40 percent of the reported catch . ' 

 (emphasis added) 



The estimates from these studies actually refer to the proportion of sublegal fish that 

 are killed for every legal fish landed and reported. These estimates are nol mortality 

 rates for fish that are encountered, caught and released (i.e. shakers). 



'Recent studies of the ocean troll fishery in Alaska (Wertheimer, 1988) 

 estimated a hooking mortality rate of about 25 percent for chinook 

 salmon. ' 



"PFMC assumes a shaker mortality of 30 percent from the use of barbed 

 hooks and 26 percent for barbless hooks. " 



These estimates refer to hooking mortality rates for fish that are encountered and 

 released, and are appropriate measures of shaker mortality. However, the authors 

 failed to specify to which species the PFMC estimates referred. It is important to note 

 that these estimates will vary by species, fishery location, gear type (as is apparent in 

 the PFMC estimates), etc.. 



"The values presented above suggest that shaker mortality is between 25 

 to 50 percent of the ocean catch. " 



"From the PFMC and USFWS data collected from Oregon and northern 

 California, an annual shaker morality (sic) value of between 30 and 40 

 percent seems appropriate for Oregon. " 



The authors erroneously combine estimates of the proportion of sublegal fish that die 

 for every reported fish landed with estimates of fish that die after being encountered 

 and released (shaker mortality) to derive a range of "shaker loss" estimates. These 

 different types of fishery mortalities are not synonymous, and cannot be combined into 

 a single range estimate. 



The authors also combine mortality estimates for different species into one generic 

 estimate. The mortality rates can vary substantially for different species and sizes of 

 fish. It would have been more appropriate to present species-specific shaker mortality 

 estimates over a number of years to more accurately portray the range of possible 

 estimates. 



The Pacific Salmon Commission reviewed all available literature on hooking mortality 

 for commercial troll chinook fisheries and concluded that a reasonable estimate of this 

 mortality was from 20 to 30 percent (PSC, 1987). These estimates correspond with tiie 

 study by Wertheimer (1988) and are substantially less than the range estimate presented 

 by the autiiors. The 30 to 40 percent estimate by the authors does not seem 

 "appropriate". 



A-8 



