State of Aquaculture Management for Optimal Rearing of Eel Anguilla japonica

Abstract

This study was conducted to investigate the production, elver stocking, rearing facilities and rearing method of eel culture to determine aquaculture management conditions for optimal rearing of eel Anguilla japonica. The production of eel culture was evaluated by the proportion of eels from the main inland fin fish species production in Korea. Elver stocking was assessed by the elver stocking densities of pond and recirculation culture. Rearing facilities were investigated according to the rearing tank size proportion of the pond and recirculation culture. We selected sample farms by region and by size. We visited sample farms and recorded the number of elvers stock for pond area, size of tanks, feed and feed quantity, and the size and number of harvest eels. The production capacity of Jeollanamdo and Jeollabuk-do were 71.9% and 21.3% respectively. This production quantity represented 93.2% of the total Korean eel production quantity. In Jeollanam-do, there are 236 eel farms, 202 pond farms, and 34 recirculation aquaculture facilities. The elvers' first density data by each aquaculture method revealed that elvers' first density varied more in recirculation system farms, as compared to pond aquaculture. In intensive pond farms, the elvers' first density decreased as the size of farm increased. There was a correlation between the size of tank(x) and the facility of a water wheel for dissolved oxygen in pond culture systems(y=0.022x-0.494; R 2 =0.860). Another strong correlation was found between the weight of eel(x) and eel density(y) in pond culture systems(y=283.5x-0.27; R 2 =0.992). Finally, there was a strong correlation between the length of eel(x) and the weight of eel(y) in intensive pond culture(y=0.0005x-3.2783; R 2 =0.9775). The final survival rate did not differ significantly among pond sizes and culture types.

Comparison of Major Nutrients in Eels Anguilla japonica Cultured with Different Formula Feeds or at Different Farms

“…In addition to price increases for A. japonica elvers, overall changes to eel culture, such as increases in the cost of raw materials for formula feeds (FFs), labor costs, and various expenses, have maintained constant pressure on eel farmers. In response, researchers have examined the use of FFs with no or reduced amounts of fish meal; how to lower the mortality rate; the development of functional feed additives; the application of high-density culture; and the relationships between rearing tank size and stocking density, between body weight and stocking density, and between body weight and daily feeding rate (Bae et al, 2008;Choi et al, 2008;Hwang et al, 2010;Son et al, 2011).…”

“…In addition, these eels are common freshwater fish that have been cultured for a very long time (Liao, 2002). The eel aquaculture industry in these countries has been growing every year; for example, in Korea, production increased from 2,739 tons in 2000 to 6,766 tons in 2009 (Son et al, 2011).…”

The effect of temperature on the physiological condition and growth performance of freshwater eel elver Anguilla bicolor bicolor McClelland, 1844

“…Deelder (1984) proposed that European eel A. anguilla can adapt to the water temperature at a range from 0 to 30°C. The feeding activity in A. anguilla was stopped in less than 10°C and more than 38°C (Sadler, 1979) and less than 10°C and more than 36°C in A. japonica (Son et al, 2011). Tesch (2003) has shown that the optimum of water temperature for rearing of A. japonica elver is at a range of 24-28°C and 23-26°C for A. anguilla.…”