Factors Affecting Stress Management in Shrimp Farming

What causes stress to Shrimps?

1. Biological Factors

1. 1. Biomass reaching beyond the pond carrying capacity, high density with poor infrastructural facility, over dominance of disease-causing agents and parasites.
   2. Over blooming of toxic planktons
   3. Presence of competitor and weed fishes. 

2. Procedural factors

1. 1. Delay in health check and sampling
   2. Cast netting during sunny weather climate, exposing the animals to hot temperature.
   3. Delay in shifting shrimps from nursery to grow-out or from pond to pond.
   4. Pond bottom disturbance during partial harvesting. 

3. Physical and Chemical factors 

1. 1. Quality of the feed used in the farm has got a direct impact on the growth and health of the shrimps as it is the main source of energy. Nutrients and energy provided by the feed are essential to maintain the homeostasis of the animal, along with optimal immune function. Poor quality feed may lead to imbalance in nutrients, vitamins, and minerals to shrimps.
   2. Low dissolved oxygen level because of insufficient aerators and other managerial issues. All the living organisms in the pond ecosystem utilize the dissolved oxygen for respiration and metabolic activities.
   3. Toxic gas formation because of over feeding, poor pond bottom management and water quality management. Once the pond ecosystem is deteriorated, shrimp need more energy to overcome stress resulting in slow growth and poor survival.
   4. High/heavy diurnal fluctuation of water quality parameters like pH, dissolved oxygen, salinity, temperature, etc. also leads to stressful condition to shrimps.
   5. Sudden change in weather condition (unexpected rain, heat wave, cyclone, etc.) or during seasonal change can alter the water quality parameters leading to stress.
   6. Usage of chemicals, sanitizers and molting inducers may alter the water quality parameters or even it can cause damage to cuticle of shrimps leading to stress conditions.
   7. Sudden changes in water quality parameters while adding new water.

General symptoms of stress

With close observation of the shrimps and its behavior, one can easily understand whether the animals are passing through stress condition or not.

In general, when the shrimps are exposed to stress condition, due to melanosis, the body of the shrimp changes to purple in color. Reddish or cut antennae along with purple colored walking legs, swimmerets and uropod can be found in animals exposed to stress.

Sometimes due to poor dissolved level or presence of toxic gases, we can find blisters, swelling, color change or even chocking of the gills.

Partial molting, rough cuticles and rough antennae indicates the stress due to hardness and mineral imbalance in the pond ecosystem.

We can observe surfacing of shrimps and parking of moribund animals in the dike side because of poor water quality parameters and virulence of pathogens.

Shrimps are invertebrates and it doesn’t have a developed immune system. So, every time it needs to fight against the stress or pathogens for their survival. We can observe sudden hike in feed consumption in the early stage of stress and if they cannot overcome the stress situation, we can see gradual drop in the feed intake or sudden stop in feed consumption. Once the animals are subjected to stress, majority of the energy will be utilized for recovery purpose. Whereas in normal condition, the excess energy will be utilized for digestion, maintenance, disease resistance and growth.

How to mitigate stress conditions?

Following the BMP (Best Management Practice) is the only option to manage or mitigate stress during shrimp farming. Keeping in mind about all the factors resulting in stress, we need to act from the pond preparation till harvest. We can use biological method, Chemical method, or both combinations to manage stress during shrimp farming.

Biological Method

Basically, targeting to increase the carrying capacity of the pond and restricting or nullifying the entry of pathogen into the system. Which includes,

• Enriching the soil by adding required quantity of minerals and nutrients according to the soil profile during pond preparation.
• Implementing biosecurity protocols to eradicate and restrict the entry of pathogens, carriers, competitors, weed fishes & shrimps, toxic substances into the system.
• Maintaining optimum water quality parameters with less diurnal fluctuations throughout the crop.

• Maintain optimum primary productivity in the pond during stocking.
• Reducing shrimps’ exposure to atmosphere especially during health check and sampling. Complete such activities in the early hours before temperature rise.
• Farming with reduced density during unfavorable conditions (low salinity, High salinity, seepage ponds, rainy season, etc.).

Chemical Method

Discussing about chemical method, it is the nutritional part ingesting to shrimp for its biological and physical activities throughout the crop. Feed and health supplements provide required energy for all activities and growth of the animals.

• Species specific diet with balanced nutrition can make shrimps grow faster and avoid stress conditions (Gamma for vannamei & Kuroline for Monodon). It also enhances disease resistance capacity of shrimps and helps in fast stress recovery during unfavorable conditions.
• Usage of high-performance feed (Xpand) with high inclusion of marine animals as protein source can support farmers to gain faster growth in normal conditions. Added with antioxidants, anti-stress, and immune boosters, it can act as a protective shield against disease causing agents and to overcome stress during unfavorable pond conditions.
• Using feed supplements and health care products to develop the disease resistance capacity and boost immune system can support shrimps during stress condition.

Relaxx is a unique combination of natural ingredients designed to improve the immune system of young and adult animals and help them to overcome stress challenges that may occur during the culture cycle. It is a blend of natural products containing prebiotics, phytogenic, vitamins, organic trace minerals and toxin binders to stimulate immune response and to inhibit pathogenic bacterial actions. It can support in eliminating the adverse effect of ammonia and help in quick wound recovery. It also acts an effective binding agent to adsorbpathogenic microorganisms, enzymes and toxins (including mycotoxins due to ion exchange capacity).

Summary

About Skretting

Skretting is a global leader in providing innovative and sustainable nutritional solutions and services for the aquaculture industry working closely with shrimp and fish farmers. Skretting has 30 production facilities in 18 countries on five continents and manufactures and delivers high-quality feeds from hatching to harvest for more than 60 species. The total annual production volume of feed is more than 3 million tonnes. It is headquartered in Stavanger; Norway and it employs 4,000 employees. Its team of more than 140 employees is dedicated to Innovation that works on the core competencies of nutrition, feed production and health for aquaculture. In India, we have head office in Hyderabad and our manufacturing footprint in Surat, Gujarat.

For further information, kindly write to us at contact.india@skretting.com or visit our website: www.skretting.in