31 



We have identified six factors we believe need to be analyzed and 

 considered prior to any reclassification of Snalce River fall chinook. 

 Highlights of our analyses are as follows: 



1. Escapeaent 



The recent year average of non-hatchery spawned adult Chinook passing 

 upstream of Lower Granite Dam (1991 to 1994) is SIO fish. This is 55% 

 higher than the 1983 to 1990 average of 330 fish. After the effect of 

 "mining" has been accounted for, the 1991-94 average of 512 fish is 12% 

 greater than the 1983 to 1990 average of 456 fish. By either analysis, 

 the population has increased since first being listed as threatened. 



2. Likelihood of Extinctioo 



We analyzed the probability of extinction using both the original Dennis 

 extinction model and a bootstrap model, and compared performance between 

 pre-listing and post-listing time periods. The outlook using data 

 through 1990 is very pessimistic for either model, with the probability 

 of . extinction being greater than 97%. The addition of data through 1994 

 considerably improves the assessment of the stock. Over 50% of the 

 simulations using the bootstrap method resulted in populations greater 

 than 5,000 fish in 100 years. The Dennis model responded similarly with 

 the probability of extinction (extinction < 30 fish) dropping to 68%. 



3. Probability of Persistence with Respect to SMrviral 



The STFA analyzed the probability of persistence for the draft 1994-98 

 hydro biological opinion. Depending upon the assumptions in it, they 

 concluded that the proportion of yearly escapements at or above 300 for 

 a 24-year period ranged from .44 to .95. Further, the DFOP plan 

 assembled by the States and Tribes estimated that the proportion of 

 yearly escapements at or above 300 for a 24-year period is always 1.00. 

 Although it is uncertain how the hydro system will be operated, it seems 

 certain that the hydro system management, once defined, will increase 

 the probability that escapement will exceed 300 fish. 



4. Spairaer-Recruit Relationship 



A Ricker spawner-recruit relationship was derived from the data. If the 

 data are accurate, a total of 440 "natural" adults or 472 total spawners 

 are needed to produce maximum sustained yield under the present 

 conditions of reduced habitat availability and quality. The number of 

 spawners that would produce the maximum return are 516 "naturals" or 570 

 total spawners over Lower Granite Dam. However, given that 1) there are 

 measurement errors and confounding environmental influences in the 

 database; 2) there is little evidence of density-de];>endent mortality 

 shown; and, 3) the estimated return per spawner was 3:1 for the 1975 

 observed escapement of 1000 spawners, we conclude that escapements on 

 the order of double the MSY (1,000 fish) would produce strong returns. 

 Recent year escapements are on the order of these estimates. 



5. Forecasts of Adult Returns 



In proposing a change in status, NMFS has used the 1995 forecast as 

 evidence for changing the listing. Past forecasts for Lower Granite Dam 

 escapement are only available for 1993 and 1994. The forecasts were 

 substantial underestimates (62% in 1993 and 47% in 1994). The continued 

 use of forecasts by the agency when they have been shown to be so 

 significantly in error in the past, is not consistent with the ESA 

 rquirement to use the best available scientific and commercial data. 



6. Hatchery Strays and Genetic Integrity 



Hatchery strays from both the Columbia and Snake Rivers have been 

 documented since 1983. We evaluated the effect of straying on the 

 natural escapement gene pool. If both Snake and Columbia River hatchery 

 strays are a concern and fitness values of .5 and 1.0 are used, the 1994 

 gene pool is composed of 24% and 10% "natural* genes. A similar 

 analysis on the Lyons Ferry hatchery brood stock indicates that the 



