NOTE Garlich-Miller and Burn; Estimating the harvest of Odobenus rosmarus divergens in Alaska 



1045 



where R 



MTRP 



WHMP - 



correction factor for noncompliance; 

 and 



a subset of the numljer of wahaises 

 recorded through the MTRP with re- 

 ported kill dates and locations that 

 coincide with WHMP operations (pre- 

 sumed to have been recorded through 

 both the MTRP and the WHMP). 



The difference between the two methods was not sta- 

 tistically significant for any year. Comparisons of the 

 1992 MTRP and WHMP harvest data suggests that 

 the WHMP monitors were unable to account for all 

 the retrieved walruses landed during the monitoring 

 period. In this instance, the MTRPj^^^^^^i was considered 

 the minimum estimate of the statewide harvest. 



The standard error of this ratio estimate is calcu- 

 lated according to Snedecor and Cochran ( 1967, p. 

 537) by treating each of the three villages as inde- 

 pendent estimates of overall compliance. Data from 

 the village of Wales were not used in the analysis 

 because of small harvests and a lack of independence 

 between the WHMP and MTRP programs in that 

 village. 



Assuming the estimated compliance with the 

 MTRP is uniform throughout the full range of wal- 

 rus hunting villages, the total MTRP harvest can be 

 adjusted as follows: 



TV = MTRProtai x R, 



(3) 



where MTRP 



Total  



the total number of walrus re- 

 corded through the MTRP. 



Results 



Data from the MTRP and WHMP are currently avail- 

 able for the years 1992-97 (Table 1 ). Estimated com- 

 pliance with the MTRP (the reciprocal of R) ranged 

 from 63% to 99*7^. Harvest estimates based on the 

 prediction equation and the proportional equation 

 differed depending on the proportion of animals re- 

 corded through each of the two monitoring programs. 



Discussion 



Prior to 1997, the FWS used WHMP data collected 

 annually at Gambell, Savoonga, and Diomede as an 

 index for estimating the total statewide harvest of wal- 

 rus. One drawback of this method has been that the 

 equation assumes that the relation between the hunt- 

 ing success of WHMP and non-WHMP villages is con- 

 stant over time (Fay et al., 1997). hi fact, recent har- 

 vest data have shown that the relative hunting suc- 

 cess of each village is highly variable. The annual har- 

 vest at each village is subject to large interannual varia- 

 tion, presumably as a result of weather and ice pat- 

 terns affecting the availability of walruses to hunters 

 at a given geographical location (Garlich-Miller-^). 



One advantage of the proportional equation (Eq. 3) 

 over the prediction equation (Eq. 1) is that it can 

 account for variability in the relative success of hunt- 

 ing villages. For example, on the basis of comparable 

 numbers of walrus recorded through the WHMP in 

 Gambell, Savoonga, and Diomede in 1995 and 1996, 

 the prediction equation produced remarkably simi- 

 lar harvest estimates for the two years (1974 and 

 1994 walrus, respectively). Although MTRP compli- 

 ance rates were also comparable for these years, the 

 proportional equation, in which statewide MTRP data 

 wei'e used, produced hai-vest estimates that were mark- 

 edly different ( 1681 and 2481 walrus, respectively). We 



