Effects of minimum dissolved oxygen setpoints for aeration in semi-intensive pond production of Pacific white shrimp (Litopenaeus vannamei)

Abstract

Aeration is considered one of the most critical factors in shrimp farming as it affects the metabolism of shrimp and other living organisms within a pond. Maintenance of proper dissolved oxygen (DO) concentrations is critical, as low DO can cause stress, lower resistance to disease, and inhibit growth. Although the effects of single, short-term hypoxia events have been widely studied, little to no research has examined effects of repeated exposure to hypoxia during multiple diurnal cycles that shrimp may experience in aquaculture ponds. Even though the concept is simple, proper DO management is not simple. It is dependent on numerous factors and often based on anecdotal recommendations. The present trial was conducted to help elucidate the effects of DO management strategies on shrimp performance. The trial examined the effects of three different DO set points for automatic aeration on shrimp production and water quality parameters in earthen ponds. In sixteen earthen ponds (0.1 ha), juvenile Pacific white shrimp (⁓0.030 g) were stocked at a density of 25ind/m2. Minimal DO setpoints that activated automatic aeration in each of the treatments were 2.5, 3.5, and 4.5 mg O2/L, respectively. Shrimp were fed using the AQ1 passive acoustic monitoring system that was set to not feed while DO was below the threshold of a given treatment. Each of the treatments was applied to 5 ponds, except for treatment 1 (2.5 mg/L) which was applied 6 ponds as it was considered of higher risk. Shrimp growth performance and water quality indicators were monitored weekly. At the end of the 79–81-day trial, results showed that different aeration control treatments had no significant effect in terms of growth performance, feed inputs or productivity parameters. The final weight of the shrimp ranged between 33.3 and 33.6 g, with average final yields of 7500–8500 kg per ha. Nonetheless, mean electrical costs differed significantly between treatments, with higher DO setpoints treatments exhibiting a higher aeration cost with no discernible benefit. Water quality parameters showed no significant difference, except for morning and afternoon DO concentrations.