Stress Management in Shrimp Farming

Over the last twenty years commercial aquaculture has experienced spectacular growth. A significant component of the fish and shrimp-based protein that humans consume, especially in first world countries, is now provided by these activities.

Fluctuating environmental factors and operational challenges can significantly stress shrimp, impacting their overall well-being, immune response and growth. By understanding the root causes and implementing effective mitigation techniques, we can pave the way for sustainable and successful shrimp farming practices.

Stress is “a measurable alteration of a physiological steady state that is induced by an environmental change and that renders the individual more vulnerable to further environmental change.” Essentially anything, whether it is external or internal that disturbs the “normal” physiological balance can be stress.

Stress is a normal and natural phenomenon, and it is impossible for life to exist without it. Signs of stress can be overt, such as sluggishness, lack of feeding activity, slow growth, molting difficulties, hyperactivity, death, or hidden until animals become ill. The action of stressors on shrimp is varied and not widely studied. One consistent feature seems to be an elevation in blood glucose levels.

What are stressors?

Stressors are how animals become stressed. Many stressors have been identified that impact aquaculture operations. Some of these can be easily and cost effectively controlled, and others cannot at any cost.

Stressors in aquaculture:

1)       Ammonia

2)       Density

3)       Dissolved oxygen

4)       Heavy metals

5)       Salinity fluctuations

6)       Nitrate

7)       pH fluctuations

8)       Nutrition

9)       Pesticide 

10)     Turbidity

11)     Diseases

12)     Temperature fluctuations

13)     Handling

Factors affecting stress in shrimps

1.Environmental Factors

Fluctuations in water quality parameters, temperature, and inconsistent oxygen levels are key environmental factors that contribute to stress in shrimp. By ensuring timely and accurate measurement of these parameters, along with responsive management practices, farmers can significantly reduce shrimp stress. This in turn mitigates the symptoms often observed, such as slow growth, reduced feed conversion ratio (FCR), increased mortality, and susceptibility to disease. Maintain min water level 1.4 mt to maintain water holding capacity.

2.Handling and transportation

Operations such as juvenile transportation and pond transfers are when shrimp are particularly susceptible to increased stress levels. Adhering to best practices in transportation methods and pond design for shrimp transfer can help reduce these stress events, ultimately contributing to the shrimp's overall health and strength. By focusing on these critical periods, farmers can better ensure the vitality and robustness of their shrimp populations.

3.Overstocking

Understanding your pond's carrying capacity is critical to avoiding overstocking, determined by factors like pond type and infrastructure. Awareness of infrastructure limitations is key to reducing stress and improving shrimp survival rates.

How to control stress in shrimp farming

1.Immune Response

Managing stress effectively can have a significant positive impact on the shrimp's immune system. Stress often leads to the suppression of the immune system, making shrimp more vulnerable to diseases. When stress is minimized, the immune system can function at its best, allowing the shrimp to fight off diseases more efficiently.

2.Decreasing Susceptibility to Pathogens

Stressors like overcrowding, poor water quality, or insufficient oxygen levels can compromise the protective barriers of shrimp, making them more susceptible to pathogens. Effective stress management creates an environment where these barriers are strong, reducing the likelihood of pathogen entry and subsequent disease.

3.Nutrition

This is a complex issue as most dietary nutrient requirements are determined in the laboratory under stringent conditions that have nothing to do with the stressful world of the shrimp farm. Certainly, if deficiency symptoms are present below a certain level a nutrient, then the diet in the field must have at least these levels. Though higher levels may be required depending upon the cultural conditions. It is known that shrimp consume an average of around 60% of the feed that they are fed during their life cycles in a pond, with the amount likely varying with respect to the size of the animal, the size of the ponds, the densities of the animals in the ponds and the feeding strategy.

4.Optimal Energy Use

Under stress, shrimp tend to use more energy for survival responses (like rapid swimming or jumping), which takes away from the energy that could be used for growth. Effective stress management ensures that the energy is optimally distributed towards growth, moulting, and reproductive processes. This can be achieved by maintaining ideal water conditions, providing high-quality feed, and implementing proper aeration systems to ensure sufficient oxygen levels.

Stress Control Solutions

• Maintaining water quality for shrimp
• Optimum stocking density
• Control Ammonia and Nitrate
• Maintain Biosecurity to reduce the Disease Outbreak
• Beta Glucans
• Vitamin C and E supplementation
• Chelated Trace minerals
• Probiotics for Shrimp

Nutritional solutions for optimum shrimp health and manage stress:

• Optimum shrimp health starts with ensuring healthy larvae.  A stable microdiet that delivers right nutrition while maintaining the pond ecosystem is required for good larvae development.   Skretting’s new generation shrimp hatchery feed diet, Elevia, is one such solution that is Inspired by Nature to improve FCR, feed consumption and post larva robustness.  Similarly, solutions like Lorica are the right inclusions for nursery diet as immunostimulants present in the feed help to ensure higher survival rate and better growth.
• During culture, it is necessary to ensure diets that fulfill the nutritional requirement of shrimp physiology.  Skretting’s shrimp grower diets, Gamma for L. vannamei and Kuroline for P. monodon have been developed after extensive research into shrimp physiology, eating habits and requirements.  With higher digestible marine protein and phospholipids, they ensure a balanced diet for robust shrimp culture.
• As diseases become prevalent and the culture become more susceptible to disease challenges like EHP, the level of stress also increases significantly under disease conditions.  In these circumstances, feeding a functional feed like Armis, Skretting’s latest innovation to build shrimp resilience, ensures healthy gut management and effective management of EHP and related stressors.
• Health supplements like Relaxx that contains phyto-biotics, micro minerals, vitamins and antioxidants are also designed to manage the various stress factors during culture.

Summary

The key to the management of stress in farmed fish and shrimp is avoidance through the use of right animal husbandry techniques, optimization of animal genetic tolerances, appropriate nutritional and feeding strategies and the selective use of biologically active compounds to promote heightened immunity during times of stress.

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. Our purpose is ‘Feeding the Future’. 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