FISHERY BULLETIN: VOL. 78, NO. 4 



i.e., catch this month is equal to the catch during 

 the same month last year, adjusted by a difference 

 of the weighted sums of the forecasting errors over 

 the previous 4 mo. If the forecasts this year have 

 consistently underpredicted compared with last 

 year's forecasts, then the estimated catch is in- 

 creased, while if the forecasts this year have 

 consistently overpredicted compared with last 

 year's forecasts, then the estimated catch is 

 decreased. The forecast maintains a balance be- 

 tween keeping the catch in equilibrium and keep- 

 ing the error in equilibrium. 



This impression of a yearly cycle with variabil- 

 ity is reinforced when examining the polynomial 



Table 9. — Estimated cross-correlation function, impulse re- 

 sponse function, and noise autocovariance function for a 

 catch-effort transfer model for the Hawaii skipjack tuna fleet, 

 1964-78. 



Table ll. — Parameter estimates for transfer model. Model (5) 

 (see text). (Based on 180 observations.) 



Lag 

 (mo) 



Estimated 

 cross-correlation 



Estimated noise 

 autocovariance 



SE 



Estimated 



impulse 



response 



weights 







1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



14 



15 



16 



17 



18 



19 



20 



21 



22 



23 



24 



25 



26 



0.651 



.080 



.070 



.086 



-.033 



.044 



-.098 



.099 



.103 



-.017 



.043 



-.040 



-.20 



.026 



-.109 



.003 



-.098 



.014 



-.110 



-.037 



.006 



-.006 



-.108 



.012 



-.108 



-.001 



-.108 



0.49 



.21 



.16 



.16 



.10 



.07 



.03 



.13 



.14 



-.05 



-.14 



-.26 



-.05 



.05 



-.12 



-.16 



-.01 



-.05 



-.12 



-.12 



-.16 



-.11 



-.18 



-.21 



-.09 



-.08 



0,10 

 .12 

 .12 

 .13 

 .13 

 .13 

 .13 

 .13 

 .13 

 .13 

 .13 

 .13 

 .14 

 .14 

 .14 

 .14 

 .14 

 .14 

 .14 

 .14 

 .14 

 .14 

 .15 

 .15 

 .15 

 .15 



8409 



1.035 



.903 



1.111 



-.431 



.566 



-1.269 



1.276 



1.334 



-.215 



.556 



-.517 



- 1 .555 



.338 



- 1 .404 



-.038 



-.415 



.043 



- 1 .271 



.185 



- 1 .422 



-.475 



.080 



-.075 



- 1 .393 



.181 



- 1 .390 



Table 10. — Parameter estimates for transfer model. Model (4) 

 (see text). (Based on 180 observations.) 



Parameter 



Estimate 



suppressing 



backforecasting 



SE 



Estimate using 

 backforecasting 



SE 



O>0 



e, 



X^ statistic 

 on residuals 



Residual 

 mean square 



Residual SE 



Residual mean 



7.5989 

 - 47621 

 -.32874 

 -.17034 

 -.20033 

 .83384 



0.69403 

 07993 

 .08734 

 08803 

 07905 

 05271 



8.0003 

 -.48894 

 -.32633 

 -.14853 

 -.17506 

 .99587 



0.83561 

 .07851 

 .08541 

 .08666 

 07822 

 .00707 



34.953 with 43 df 



83,323 

 288 66 

 -15.152 



32.018 with 43 df 



71,300 

 267.02 

 0.18650 



Table 12. — Catch forecasts for 1979 for the Hawaii skipjack 

 tuna fleet from Models (1),(4), and (5) (see text). 



Model 



Table 13. — Predicted and observed number of fishing trips for 

 the Hawaii skipjack tuna fleet in 1979. 



Month 



Original prediction 



Updated prediction 



Observed 



Jan 



Feb, 



Mar. 



Apr. 



May 



June 



July 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



98.93 

 97.50 

 101.06 

 122.30 

 174.00 

 196,16 

 209.37 

 183.04 

 139.18 

 121.20 

 104.23 

 100.92 



167.71 

 187.36 

 206.14 

 179.81 

 138.73 

 120.45 

 104.83 

 100.51 



53 



75 



78 



118 



173 



182 



200 



174 



84 



84 



51 



109 



Table 14. — Updated forecasts of total catch for 1979 for the 

 Hawaii skipjack tuna fleet. 



Model 



Month 



(4) 



(5) 



(1) 



Observed catch 



May 



June 



July 



Aug, 



Sept, 



Oct. 



Nov. 



Dec. 



Total 



393.214 

 547.014 

 644.638 

 500,151 

 293,130 

 220,557 

 174,567 

 130,947 



2,904.218 



382.430 

 586.400 

 705.137 

 527,945 

 283,067 

 197.953 

 164 720 

 136,831 



2.984 483 



401,874 

 589.524 

 668.895 

 521.456 

 289.516 

 222.806 

 173.594 

 133.148 



3,000.813 



470.545 

 358510 

 600.693 

 600.520 

 148,307 

 79,336 

 27,5084 

 84,7755 

 2,370,1949 



894 



