05 Jun 2019
Worried About Shrimp Disease? Stop Stressing Out Your Animals
Written by Zach Stein

Every year, disease is the number one issue on shrimp farmer’s minds (although low prices are creeping up there). It is the source of the largest losses of shrimp on the farm and farmers are always looking to stay just one step ahead of the latest disease.

There are a number of ways to lower the likelihood of disease on the farm – from better genetics to biosecurity – but today we want to write about one way that every single farmer can help protect their shrimp from disease – by reducing their stress levels.

Stress – the Bringer of Disease and Killer of Shrimp

Stressed shrimp are far more likely to fall to a disease than non-stressed animals. Whether it be Whitespot, EMS, or EHP, the more fluctuations a shrimp endures in its environment, the lower its defenses will be should it comes across a pathogen.

While there is not a pandemic like there was with EMS in 2012, disease is having a major impact on the industry, primarily with Whitespot and EMS in Thailand, India, and Vietnam. Some estimate that over 50% of India’s potential harvest fell to Whitespot.

While parts of the solution to disease are further up the supply chain in genetics and SPF hatcheries and broodstock, part of it is in farm management as well and keeping your shrimp as happy and healthy as possible.

Some Ways to Avoid Stress in Your Shrimp

What will stress out your shrimp? The answer is simple – anything that fluctuates. Shrimp thrive in constient and die in variable environments. So here are somethings that farmers around the world are doing to keep their pond environments more consistent:

  • Shade Cloths. We are seeing more intensive farms uses shade cloths to cover the ponds. Not only will your staff thank you for keeping them out of the hot sun, but it will help keep your animals in a more controlled temperature.
  • Better Aeration. Fluctuations in dissolved oxygen are some of the most intense for your shrimp. While some drop in dissolved oxygen at night is unavoidable, you can install enough HP of aeration to keep this at a minimum and ensure high surface area exposure of your pond’s water to the environment.
  • Zero Water Exchange. This is a new practice being tried both in intensive farms in Asia and extensive in LatAm. Instead of bringing in new water and flushing out old, used water is recycled through a reservoir where it can be treated. New water (to replace what has evaporated) is treated in a reservoir as well before entering the farm, thus working as much as possible to keep environmental pathogens out of the farm.
  • Water Filtration. For more of a capital investment, farms are installing high quality water filters to take a step further in keeping out environmental pathogens.
  • Greenhouses. Another high cost capital investment that only really applies in super high density farms, greenhouses help keep rain out of the ponds which has two major benefits when it comes to shrimp stress. The first is keeping salinity levels more constant and the second is avoiding the acoustic stress of the rain hitting the water, which drives the shrimp to the bottom of the pond where more of their filth has accumulated
  • Pond Sludge Draining. Commonly called a shrimp toilet, this paired with a pattern of aerators to create a “swirling” current in the pond will help “flush” the excess sludge that builds up at the bottom of the pond. The goal is a clean pond bottom where pathogens cannot take root and grow to infect your water.
  • Better Water Quality Monitoring. Finally, you can do all of this, but still see unpredictable changes in water quality which stress your shrimp out. Until now, continuous tracking of water quality has been very expensive and hard to maintain over time. We are working on that with Osmobot, a new kind of water quality sensor that costs 90% less than existing options and is built to be maintained by you and your staff.

Conclusion  

Looking to reduce fluctuations in the environment of your shrimp pond and thus the stress of your animals? It may take some cash up front, but the savings in boosting your survival rates can be huge in the long run.