Prista et al: Use of SARIMA models to assess data-poor fisheries 
177 
B 
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr 
( Fo ) ( 1 ) (2) (3) (4) (5) (6) (7) (8) ( 9 ) ( 10 ) ( 1 1 ) ( 12 ) 
Apr May Jun Ju! Aug Sep Oct Nov Dec Jan Feb Mar Apr 
( Fo ) ( 1 ) (2) (3) (4) (5) (6) (7) (8) ( 9 ) ( 10 ) ( 1 1 ) ( 12 ) 
D 
"O 
c= 
03 
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr 
( Fo ) ( 1 ) (2) (3) (4) (5) (6) (7) (8) ( 9 ) ( 10 ) ( 1 1 ) ( 12 ) 
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr 
( Fo ) ( 1 ) (2) (3) (4) (5) (6) (7) (8) ( 9 ) ( 10 ) ( 1 1 ) ( 12 ) 
Figure 3 
Forecasts and forecast prediction intervals (Pis) of meagre ( Argyrosomus regius) landings. The 
dashed vertical line is the forecast origin (“Fo”, April 2007). The gray circles and line represent 
the monthly forecasts. The black circles and line represent observed monthly landings. The dashed 
gray lines represent the upper and lower 75%, 95%, and 99% prediction intervals. (A and B) Single 
step prediction intervals (PI ssA ) of transformed centered landings and back-transformed landings, 
respectively in C and D. Multistep prediction intervals (PI ms /,) of transformed centered landings 
and back-transformed landings, respectively. 
Model forecasts and performance 
The model forecasts presented two local maxima (May 
2007 and September 2007) followed by a four-month 
period of low landings (December 2007 through March 
2008) and an increase in the last month (April 2008) 
(Fig. 3, Table 3). This pattern in forecasts matched the 
one in observed landings and the only deviations were 
that the actual maxima took place one to two months 
later and the winter trough was sharper than that pre- 
dicted by the model (Fig. 3). RMSE during the hold-out 
period (0.234) was =1.5 times the RMSE of the fitting 
period. Eight of the 12 forecasts registered negative 
errors, but the low ME and PE indicated that under- 
estimation was minor in global terms. APE was large 
in August, September, December, and April, reflecting 
the delay in cessation of the 2007 fishing season and 
the hastening of the 2008 fishing season. Maximum 
APE coincided with the lowest landings (February), 
and the minimum APE with the first month forecasted 
(May) (Table 3). MAPE was 40.3%, reflecting the lagged 
seasonality and the low landings observed during the 
winter period. 
