A review on recirculating aquaculture system: influence of stocking density on fish and crustacean behavior, growth performance, and immunity

Abstract

The human population is expected to reach 9.7 billion by 2050. This in turn will put more pressure on the limited available resources such as land and freshwater. Combined with the high food demand, highly virulent pathogens, and worsening effects of climate change, cases of chronic hunger and malnutrition are expected to escalate in the future. Therefore, the implementation of sustainable food production systems is crucial in safeguarding food security. Recirculating aquaculture systems (RAS) have gained much attention today for the intensive production of certain aquatic species in controlled conditions. In these systems, wastewater is purified via several water purification steps and recycled back into the system. As such, water quality parameters such as water temperature, dissolved oxygen, dissolved carbon dioxide, pH, Total Ammonia-Nitrogen, nitrites, nitrates, and total soluble solutes are maintained within the desirable range required for proper growth and survival of the reared species. However, maintenance of good water quality largely depends on certain factors, most noticeably, the stocking density. Stocking densities below and above the recommended optimal levels negatively impact the behavior, growth performance, and immunity of reared animals. As a consequence, huge production losses are incurred. This review, therefore, aims to discuss the effect of stocking density on behavior, growth performance, feed utilization, and immunity of reared species in RAS. Moreover, optimum stocking densities of several aquatic species reared in RAS under certain culturing conditions are highlighted for sustainable production of food.

Effect of Animal Stocking Density and Habitat Enrichment on Survival and Vitality of Wild Green Shore Crabs, Carcinus maenas, Maintained in the Laboratory

“…There were no significant effects of stocking density on any of the vitality indices. For other decapod crustaceans inappropriate stocking density can have a negative effect on survival and growth [ 50 , 74 ]. C. maenas is a gregarious species often occurring in high densities [ 71 , 75 ] and thus maintaining them in fairly high densities probably does not cause undue stress.…”

From Aquaculture to Aquaculture: Production of the Fish Feed Additive Astaxanthin by Corynebacterium glutamicum Using Aquaculture Sidestream

“…This tremendous demand for fish cannot be met by fishery alone. Accordingly, aquaculture is the fastest-growing food production system [ 2 ], enabling the fishing industry to meet the global needs [ 3 , 4 ]. The amount of seafood bred in aquaculture systems contributed 46% of the global production (82.1 mt) in 2018, and this share is expected to reach 53% (108.5 mt) in 2030 [ 1 ].…”

“…RAS have great opportunities for waste management and nutrient recycling [ 9 ]. The lower flow rates of RAS compared to raceway systems, and the high stocking densities of RAS compared to ponds and cages lead to lesser, more concentrated effluents from the fish tanks, which can be treated more cost effectively [ 2 , 7 , 9 , 10 ]. RAS and other aquaculture effluents are mainly composed of settleable and dissolved nutrients from feces and unconsumed fish feed [ 11 ], which need to be removed in order to reuse the water for the fish tanks.…”

No effect of stocking density on the survival or size of late‐stage Delta Smelt larvae reared in a small‐scale culture system

“…In Delta Smelt, it is thought that stocking density may influence larval survival and growth, as it does in many other species (Mugwanya et al 2022). For example, late‐stage larvae (60 dph) held in 8‐L containers for 24 h at lower densities (one and two larvae per L of water) exhibit higher cortisol levels than those held at higher densities (four, six, and nine larvae per L; Hasenbein et al 2016).…”