3. Results

The quarter wise shrimp catch landings (total, mean and standard deviation) of Chilika lagoon are shown in Table 1. The total catch in first quarter Q1 (7427.36)


Table 1.

Quarter wise total, mean and standard deviation of shrimps landing in Chilika lagoon for the period 2001–2015.

was found to be maximum followed by second quarter Q2 landings (7033.78). The catch of third quarter Q3 (3216.19) and fourth quarter Q4 (3226.56) are nearly equal for the period 2001–2015. The quarterly average landings Q1 (495.15) are found to be more than Q2 (468.91), but the variation in catch in Q2 (164.69) is higher than Q1 (126.61). The mean catch of Q3 (214.41) is similar to that of Q4 (215.10), but the variation in catch in Q3 (84.03) is higher than Q4 (55.60). The variation in quarter wise shrimp catch data in Chilika lagoon was shown in Figure 2. Temporal variation using image mapping of the lagoon in Figure 3 showed that catch increases in the first decade but decreases thereafter, and in 2015, catch was found comparatively low with respect to 2010–2012. The highest peak in catch was observed during 2011 and then starts decreasing till 2015 (Figure 3).

The best fitted SARIMA model was selected based on model selection criteria (AIC and SBC), and SARIMA (0,1,1)(0,1,1)4 model with lowest AIC (509.23) and SBC (517.26) found the best fitted model Table 2. The parameter's estimate of bestfitted SARIMA (0,1,1)(0,1,1)4 model in Table 3 showed nonseasonal moving average (component) parameter Q at lag 1 (0.71, p < 0.001) and seasonal moving average parameter (0.78, p < 0.001) at lag 4 as significant effect in the developed model. Two catches of second quarter for the year 2005 and 2011 showed the significant outliers, and catch showed significantly increase during this period. The R2 value 0.70 showed the good fit of the SARIMA (0,1,1)(0,1,1)4 model. The residual of the developed SARIMA model was tested by Ljung, and Box test (p > 0.05) showed the adequacy of the fitting of the estimated models. The developed SARIMA model was validated with the actual shrimp catch data (Table 4). The annual catch prediction error for the developed model was found below 10%,

Figure 3.

Table 2.

Table 3.

89

Chilika lagoon for the period 2001–2015.

landings in Chilika lagoon for the period 2001–2015.

Temporal variation of shrimp production of Chilika lagoon ecosystem from 2001 to 2015.

Forecasting Shrimp and Fish Catch in Chilika Lake over Time Series Analysis

DOI: http://dx.doi.org/10.5772/intechopen.85458

Sl. No. SARIMA model AIC SBC SARIMA(0,1,1)(0,1,1)4 509.23 517.26 SARIMA(0,0,1)(1,1,1)4 519.19 529.32 SARIMA(1,0,1)(1,1,1)4 520.88 533.03 SARIMA(1,0,1)(1,0,1)4 558.60 573.26 SARIMA(1,0,0)(1,1,1)4 518.55 528.10 SARIMA(1,1,1)(1,0,0)4 585.03 595.85 SARIMA(0,0,1)(0,1,1)4 517.35 525.46 SARIMA(2,0,0)(1,1,1)4 519.94 532.10

Comparisons of best fitted SARIMA model with fit statistics (AIC, SBC) for quarter wise shrimp landings in

Model parameter Estimate Std. Error Prob>|T Fit Statistics Q (Lag 1) 0.71 0.11 <.0001 AIC = 509.23 q (Lag 4) 0.78 0.14 <.0001 SBC = 517.26 2011:Q2 (catch) 205.16 82.48 0.01 R2 = 0.70

Best fitted SARIMA (0,1,1)(0,1,1)4 model parameter's estimate and their significance for quarter wise shrimp

2005:Q2 (catch) 266.90 82.31 0.002

Forecasting Shrimp and Fish Catch in Chilika Lake over Time Series Analysis DOI: http://dx.doi.org/10.5772/intechopen.85458
