A pilot study of producing organic shrimp in subtropical regions: a case study in Taiwan

Summary

The study was conducted to evaluate the applicability of producing organic shrimp without using any chemicals in Ilan, Taiwan. The trials respectively employed intensive monoculture of two penaeoid species, white shrimp (Litopenaeus vannamei ) and kuruma prawn (Marsupenaeus japonicus) and extensive polyculture of kuruma prawn (0.56 m-2 stocking density) and grey mullets (500 pcs). Experimental units consisted of three earthen ponds, 900 m2 , 1100 m2 and 4600 m2, respectively with a minimal water exchange. No significant effects in shrimp growth were found with the probiotics used in the trials. Although the survival rates for both species in the first two trials were low and obviously affected by the disease outbreaks, the third trial on extensive polyculture with grey mullet achieved a high survival and growth rate (3.8 g to 37.3 g) during the 12 weeks culture period. Dissolved oxygen concentration in three ponds fluctuates on a 24-hour basis, increases during daylight hours and decreases at nighttime even dropping to a critical level of 2.03 mg/L. The results obtained from those trials indicate that the culture conditions must be carefully maintained. Although our trials did not achieve good results, they can provide some implications for future research. Also, maintaining an organic ecosystem may simply be too difficult for some aquaculture systems. Thus, it would be unrealistic to say that all aquaculture systems, at least for those we currently know, would be suitable for organic certification. However, seeking a balance between aquaculture production and environmental protection will be our ultimate goal.