Coculture of abalone (Haliotis midae) and sea cucumber (Neostichopus grammatus) to reduce tank cleaning frequency in abalone farming

Abstract

Abalone farming produces nutrient-rich sludge, and the frequent cleaning and removal of sludge from abalone tanks is labour and capital-intensive. This study aimed to assess the effect of culture methods and tank cleaning frequency on abalone growth, water quality, and sludge characteristics. The study was conducted for 16 weeks. Four treatments were used, namely, abalone cocultured with sea cucumber cleaned once (AS1) and twice weekly (AS2); abalone monoculture cleaned once (A1) and cleaned twice weekly (A2). Abalone (initial avg weight = 40.9 g) were maintained under commercial stocking conditions in flow through systems at a salinity of 35 ppt and fed a commercial formulated diet (Abfeed™) and fresh seaweed (Ulva lacinulata and Gracillaria gracilis). The stocking densities were 200 abalone m−2 and 50 sea cucumbers m−2. The sea cucumbers (initial average weight = 12.5 g) fed on the abalone faeces and leftover feed, which settled at the abalone tank's bottom (sludge). There was a significant interaction between the type of culture and the frequency of cleaning on abalone weight (F (1,476) = 12.41, p < 0.001). Abalone in the A2 treatment group showed higher growth (p = 0.006) than those of the A1 treatment group, while abalone in AS1 had significantly higher growth (p < 0.001) than those in the AS2 treatment group. Also, abalone in AS1 showed higher growth (p = 0.026) than abalone in the A1 treatment. However, abalone in AS1 had growth similar (p = 0.53) to those in A2. The survival rate of the sea cucumbers was high, however, the sea cucumbers experienced a reduction in weight regardless of the treatment. This study showed that growth optimisation in abalone farming can be achieved by cleaning tanks twice instead of once weekly. However, when abalone are cocultured with sea cucumber, tanks need only be cleaned once a week without compromising abalone growth or water quality. The coculture of abalone and sea cucumber results in an additional aquacultured product, a significant reduction in labour and other associated costs of cleaning, without an additional cost of production.

The Role of Functional Feed Additives in Enhancing Aquaculture Sustainability

“…Various techniques and systems have been developed to treat aquaculture wastewater and improve quality to reduce the water's nutrient load. They include bio floc technology, recirculating aquaculture systems, integrated multitrophic aquaculture, aquaponics, the use of biofilters, water exchange, photocatalysis, and chemicals such as Zeolite [23,26,27,[143][144][145]. However, it is either that the systems/techniques are complicated, not cost-effective, or may result in bioaccumulation in the animal, which is detrimental to the consumer in the case of chemicals [146].…”

“…To address the health of aquatic animals, antibiotics and chemicals have been used to combat diseases and parasites [21,22]. Integrated multi-trophic aquaculture (IMTA) has also been projected to reduce the nutrient load associated with aquaculture effluent, such that the waste from the fed species, which would have been discarded together with its nutrient, is used as a source of feed or fertilizer for the complementary species [23][24][25][26][27]. Similarly, photocatalysis, recirculatory aquaculture systems (RAS), and aquaponics have been used for the treatment of aquaculture wastewater.…”