Comparison of delay difference model and surplus production model applied to albacore (Thunnus alalunga) in the South Atlantic Ocean

We applied surplus production model and delay difference model to analyze the data of the southern Atlantic albacore (Thunnus alalunga) stock. Results show that the delay difference model captured annual fluctuation of catch per unit effort (CPUE) better than the Schaefer model. Akaike information criterion (AIC) also reveals that delay difference model performed better. We calculated an 80% percentile confidence interval of maximum sustainable yield (MSY) of 21 756~23 408 t (median 22 490 t) and 26 116~28 959 t (median 27 520 t) by delay difference model and Schaefer model, respectively. Results of biological reference points show that the southern Atlantic albacore stock was in a good state before 1985 buthad beenoverfished from 1985 to 2005; after that, it was rebuilt gradually but must be taken care of. The delay difference model gave more effective and conservative results than the surplus production model.