ANALYSIS AND PREDICTION OF WALLEYE POLLOCK (THERAGRA-CHALCOGRAMMA) LANDINGS IN KOREA BY TIME-SERIES ANALYSIS

Forecasts of monthly landings of walleye pollock, Theragra chalcogramm a, in Korea were carried out by the seasonal autoregressive integrated moving average (ARIMA) model. The equation of Box-Cox transformation on the walleye pollock catch data which handles nonstationary variance was Y' = (Y-0.31 - 1)/0.31. The model identification was determined b y minimum Akaike information criteria (AIC) to identify the model as a n objective criterion. Monthly forecasts of the walleye pollock landin gs for 1993-1994 were compared with the actual landings. Total observe d annual landings of walleye pollock in 1993 and 1994 were 16,610 metr ic tons and 10,748 metric tons, respectively, while the model predicte d 10,459 metric tons and 8203 metric tons (absolute percentage error 3 7.0% and 23.7%, respectively). The spectrum analysis of the monthly ca tches of walleye pollock in Korea showed some dominant fluctuations in the periods of 12 months, 4.4 years, 12.6 months and 6 months in desc ending order. (C) 1998 Elsevier Science B.V. All rights reserved.