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Sustainable Aquaculture

Fish and shrimp farming for people, profit and planet

As the world population grows, traditional fishing methods will not be able to meet the growing demand for fish. Aquaculture offers a way to meet global demand while reducing the pressure on wild capture fisheries. 

Farmed fish and farmed shrimp (prawns) are incredibly competitive when it comes to converting feed into animal protein for end consumers to enjoy. Yet, concerns about how animals are reared and the environmental impacts of aquaculture have made sustainability more important for consumers and therefore for aquafeed and aquaculture producers.  

Environmental impacts of aquaculture 

The rapid rise in demand for farmed fish presents new problems. When aquaculture is not well managed, it can have a range of adverse impacts, for example:  

  • Crop wastage resulting from poor feed management  
  • Water pollution  
  • Overuse of antibiotics linked to antibiotic resistance  
  • Disruption of local ecosystems

Through better management of water, feed and medicines, fish farming can meet the growing demand while minimizing environmental and social impacts. 

Definition

Sustainable fish farming covers a complex set of factors require multiple inputs and diverse perspectives.  

Consumer awareness of sustainable aquaculture production has led to increased interest in certification for sustainable aquaculture practices. 

The most widely used sustainable seafood certification programs are based on seven main categories, including;  

  • Legal compliance 
  • Land and water use 
  • Water pollution and waste management
  • Genetics 
  • Feed management 
  • Health medicines and chemicals management 
  • Social responsibility 
Figure 1. The seven categories on which the Aquaculture Stewardship Council (ASC) certification for Pangasius farms are based.
Figure 1. The seven categories on which the Aquaculture Stewardship Council (ASC) certification for Pangasius farms are based.

Of these, three important categories relate to feed efficiency, waste management and disease control. Within these topics, certification bodies have established specific targets in terms of feed conversion ratio (FCR), waste discharges and water pollution, and the use of medicines as prophylactic measures. These targets present challenges that farmers must face in order to comply with such certification. 

Figure 2. How feed additives support sustainable aquaculture
Figure 2. How feed additives support sustainable aquaculture

Achieving certification

Farmers are also aware that by complying with such targets, sustainability certification can offer a premium price and allow exports to higher value markets. Feed additives can be used as a tool for feed mill integrators and farmers to achieve the demanding targets imposed by certification organizations. 

The use of gut performance solutions and mycotoxin risk management can help the aquaculture industry accomplish some of the requirements for certification process without any profit loss. 

The choice of aquaculture system such as biofloc for sustainable shrimp farming or recirculating aquaculture system also has a clear impact on the sustainability and efficiency production.  

Improving feed efficiency 

Phytogenic feed additives in aquaculture (PFAs) are known to stimulate digestive secretions, increase villi length and density and increase mucous production through an increase in the number of globlet cells. As a result, phytogenics improve feed digestibility. 

Several trials were performed with pangasius to confirm the efficacy of the Digestarom® P.E.P. product line in improving feed efficiency. In a trial performed under commercial production conditions at Hung Ca farm in the Mekong Delta, two 8,000m2ponds were stocked and the fish raised to a final weight of 1.1kg. 

Dietary supplementation with Digestarom® P.E.P. led to 5.1% higher specific growth rate (SGR) and 6.7% lower FCR (Figure 3). 

Figure 3. Growth performance of the control and Digestarom® P.E.P. groups
Figure 3. Growth performance of the control and Digestarom® P.E.P. groups

Nutrient utilization improved as FCR became more efficient. Through enhanced FCR, farmers could achieve one of the most important requirements for the certification programme—nutrient utilization efficiency. This improvement also has direct positive effects on feed cost, water quality and nitrogen discharge. 

Improved nutrient sparing also reduces the impact on the environment, leading to improved water quality, pond eco-system and better sludge control. Farmers also gain the benefit of a higher quality fillet. 

Reducing nitrogen discharge 

Through improved protein utilization, phytogenic feed additives can also decrease ammonia emissions and organic matter discharge with a consequent benefit on water quality. Considering a 6.7% reduction in FCR and assuming an average apparent dry matter digestibility coefficient (ADC) of 75%, the reduction in waste output to the environment would be 21.4 tons (Table 1). 

Table 1. Nitrogen discharge reduction from the use of Digestarom® P.E.P.
* Values in tons, calculations based on ADC=75%
 ControlDigestarom® P.E.P.
Production*368.1343.4
FCR1.81.68
Feed used*662.6576.9
Waste output*165.6144.2
 Δ = 21.4 

 

Prophylactic antibiotic replacements 

Acidifiers can act in the intestinal tract to reduce pH-levels in the stomach and particularly in the small intestine, inhibiting the growth of Gram-negative bacteria through the dissociation of acids and production of anions in the bacterial cells. Acidifiers also act as preserving agents by reducing the pH of feed, and thereby inhibiting microbial growth. 

Several aquaculture trials performed with the Biotronic® product line show that through the efficacy of these products as natural growth promoters, the use of antibiotic growth promoters can be totally dismissed. This fulfils one of the most important criteria for certification without any loss in growth performance. 

In addition, the decreased uptake of biological organisms through feed will improve the health status of cultured fish, reducing disease outbreaks without any need for veterinary medicines. 

Pond management 

Intensive fish farming produces large amounts of organic waste which accumulate in the pond bottom and cannot be utilized by the phytoplankton. Oxidation of these organic waste compounds depletes the dissolved oxygen deep in pond bottom soils, leading to the formation of toxic metabolites. This contributes greatly to deteriorating water quality and disease occurrences. 

A useful and sustainable tool for managing the pond environment is the application of AquaStar® Pond/ PondZyme. This type of bioremediation uses selected strains that focus on reducing pathogenic bacteria, enhancing the mineralization or degradation of organic matter, and removing undesirable waste compounds. 

Despite not being therapeutic agents, these beneficial bacteria alter directly or indirectly the composition of the microbial community in the rearing environment, and consequently in the fish gut, improving animal health and performance. 

Probiotics for better gut health 

Preventing diseases is surely more cost effective than treating ill animals. Probiotics in aquaculture are able to modify the intestinal microbiota, secreting antibacterial substances (bacteriocins and organic acids) that compete with pathogens to prevent their adhesion to the intestine. 

Probiotics also compete with pathogens for the nutrients necessary for pathogen survival, producing an antitoxin effect. The use of AquaStar® Hatchery/Growout can improve the health status of aquatic animals by reducing diseases outbreaks and the need for veterinary medicines. 

Managing mycotoxins in feed 

Ingested mycotoxins may lead to an overall decline in performance which may ultimately result in economic losses. It is difficult to observe directly the negative effects of mycotoxins in aquaculture species as most of the symptoms of mycotoxicosis are subclinical and hard to detect. 

Several studies have highlighted the negative effects of mycotoxin-contaminated feeds in aquaculture. Some of these effects are reduced growth, increased production costs, overall negative effects on the pond eco-system, immune suppression and decreased disease resistance. 

Symptoms of mycotoxicosis in aquatic species can pass unnoticed and economic losses are usually associated with diseases outbreaks rather than mycotoxins. The incorporation of Mycofix® in aquafeed can help mitigate the negative effects of mycotoxins, mainly tissue damage, that can lead to poor growth performance and disease susceptibility. 

Figure 4. How feed additives improve the sustainability and profitability of your farm
Figure 4. How feed additives improve the sustainability and profitability of your farm
Tools for improving sustainability  

The use of feed additives through different strategies can help farmers achieve better aquaculture practices. This will enhance growth, survival and feed conversion rates, and increase tolerance to diseases, as well as better environmental conditions. Feed additives can support a more sustainable and profitable farm. 

Solutions

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