Price behaviour of selected marine fish species in Colombo market Sri Lanka

Abstract

In Sri Lanka, fish provide about 50% of the animal protein consumed, which is nearly three times the global average. The country’s fisheries, including marine, inland and aquaculture sectors, play an important role in food security and livelihoods. However, significant price fluctuations have impacted stakeholders such as fishers, traders and consumers. This study analyses price trends and seasonal patterns of selected six fish species (large pelagic and small pelagic) consumed by Sri Lankans and available in Colombo market. Monthly retail prices from January 2014 to December 2024, obtained from the Hector Kobbekaduwa Agrarian Research and Training Institute, were used to develop a forecasting model for better market insights. The Augmented Dickey-Fuller (ADF) test confirmed that the first order differenced real price series were stationary. Accordingly, the Autoregressive Integrated Moving Average (ARIMA) and Seasonal ARIMA (SARIMA) models were used for analysis with R software. Results show an upward trend in nominal prices, mainly due to inflation while real prices remain stable over time. Seasonal price index values indicate variations in the monthly average real prices of different fish species linked to monsoon seasons. SARIMA models consistently provided the best fit for forecasting the prices across allspecies. For Salaya, Hurulla, Balaya, Kelawalla, Thora and Talapath, the best-fitting SARIMA models were (2,1,2)(0,1,12)[12],(1,1,2)(1,0,12)[12],(0,1,2)(2,0,12)[12], (0,1,3)(0,0,12)[12],(0,1,5)(0,0,12)[12] and (0,1,2)(0,0,12)[12] respectively, with AICc values ranging from 1295.76 to 1674.75, MAPEs between 0.0506 and 0.0885 and R-squared values from 0.7536 to 0.9149, indicating strong predictive accuracy across all species. The findings suggest that the apparent increasing trend in nominal fish prices is influenced mainly by external factors such as inflation, supply chain disruptions and weather patterns. These results highlight the need for price stabilization and continuous market monitoring mechanism to enhance affordability and improve the value chain in the sector.