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Dr.Kada Narayana Murthy
Assistant Manager-Technical at Growel Feeds Private Limited

What are the challenges in the Shrimp farming during the Winter Crop and what precautions are to be taken to overcome them in earthen ponds during Winter?

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Nelson D. Gerundo
Nelson D. Gerundo

 

Just about everything you can imagine under the cold spell of winter in the open outdoor earthen shrimp grow-out ponds.

Some shrimp diseases are more prevalent during winter than in summer. WSSV is one of these….  Studies showed a significant increase in host survival at temperatures over 30 degrees centigrade following exposure to WSSV, while temperatures below 30 degrees resulted in accumulated mortality of 90 percent or greater (Wigglesworth, 2002).

https://www.aquaculturealliance.org/advocate/temperature-effects-on-shrimp-survival-to-disease/

Just like in the hatchery, fungal diseases are more prevalent during the winter season in the open outdoor earthen shrimp grow-out ponds ... Where everything proteinaceous becomes coated with fungal colonies from uneaten feed to dead tadpoles, dead frogs, dead mosquito larvae, dead shrimps, dead rotifers, dead copepods, and etcetera under the cold spell of the winter season in the Asia-Pacific region

https://images.saymedia-content.com/.image/t_share/MTc0NDY3NDgzNTg2MDEyODA2/saprolegnia-and-phytophthora-oomycetes-or-water-molds.jpg

Shrimps eat less when the weather is too cold and may result in a slower growth rate when prolonged cold spells occur. Night grazing is also very much less in the peak cold season contributing additional effect on slower growth rate.

Coastal brackish water during the cold “Amihan: winter season in most parts of the Philippines is not well settled yet after being made more turbid by the wet “Habagat” of the rainy season and carries more marine saprophytic bacteria including the vibrios.

https://www.divescotty.com/underwater-blog/amihan-habagat-monsoon.php

And when the coastal waters including the bottom sediments have been continuously disturbed and made eutrophically more turbid with the constant mixing of floodwaters and domestic sewer runoff, you can expect an enhanced bacterial community population and altered bacterial diversity dynamics e.g. Vibrio, Alteromonas, Photobacterium, Serratia, Pseudoalteromonas, and etcetera.

https://www.outlookindia.com/public/uploads/gallery/20200827/Typhoon_20200827.jpg

Making Vibriosis and sometimes complicated with other shrimp bacterial diseases more rampant during the Amihan winter shrimp crop cycle.

What happens after Southeast Asia becomes battered by four months of rain, typhoons, cyclones, domestic sewer water runoff into the coastal waters made worst by floods before every winter season comes.

https://s.w-x.co/util/image/w/in-typhoon_phil.jpg?v=at&w=1280&h=720

Nelson

Nelson D. Gerundo
Nelson D. Gerundo

 

Not everything is bad during the winter shrimp crop in the open outdoor earthen ponds in the Asia-Pacific Region… because cold pond water can carry more dissolved oxygen than in the warm pond water of the summer.

Shrimps are also more in demand during the winter season coinciding with many holiday celebrations around the globe.

Nelson

Nelson D. Gerundo
Nelson D. Gerundo

 

The number 1 precaution that I will recommend for shrimp farmers for their winter crop grow-out production cycle in the Asia-Pacific region is to make sure they look for the ABSENCE of septic localized multi-focal melanocytic necrobiosis of the appendages on the shrimp postlarvae they are receiving from the shrimp hatcheries indicative of infection with pathogenically chitinolytic strains of vibrios that are rampant during the winter shrimp hatchery production season in the Asia-Pacific region.

Penaeus vannamei (Postlarva 11) air freight shipment from a shrimp hatchery in the Visayas to a client in Southern Luzon intended for nursery rearing in a shrimp nursery RAS that I designed and built exhibiting septic localized multi-focal melanocytic necrobioses of the appendages upon examination immediately upon arrival during a winter season.
Penaeus vannamei (Postlarva 11) air freight shipment from a shrimp hatchery in the Visayas to a client in Southern Luzon intended for nursery rearing in a shrimp nursery RAS that I designed and built exhibiting septic localized multi-focal melanocytic necrobioses of the appendages upon examination immediately upon arrival during a winter season.

If you stock this into your shrimp pond, you will have lower survival at the nursery phase of your production culminating into the grow-out production phase.

The only way for you to find this out is to look under the microscope because you won’t see these pathognomonic lesions with your naked eyes looking at the shrimp postlarvae through the plastic bag or clear glass container e.g. beaker or bottle.

https://arkvalleyvoice.com/wp-content/uploads/2020/02/Desiderius-Erasmus-Quote-In-the-kingdom-of-the-blind-the-one-eyed-1280x640.jpg

Stealthily sick postlarvae stocked in shrimp ponds during the winter cycle... equals production problem and headache appearing at the grow-out period in the middle of the winter season.

Nelson

Nelson D. Gerundo
Nelson D. Gerundo
Original base frame source of the posted image above… Uncropped. Unretouched. Unedited. Untweaked. Straight-out-of-the-camera (SOOC) by nelson gerundo
Original base frame source of the posted image above… Uncropped. Unretouched. Unedited. Untweaked. Straight-out-of-the-camera (SOOC) by nelson gerundo
Dr.Kada Narayana Murthy
Dr.Kada Narayana Murthy

Dear Nelson,

Can you kindly send me any published articles on septic localized multi-focal melanocytic necrobiosis. 

Nelson D. Gerundo
Nelson D. Gerundo

 

Dear Narayana Murthy,

As per your request to send you any published article on septic localized multi-focal melanocytic necrobiosis, kindly send me your email address and I will only be happy to send you some important related literature from the scientific community with an additional explanation from me, off-list, on the pathobiology of septic localized multi-focal melanocytic necrobiosis. 

Kind regards,

Nelson

nelsongerundo@yahoo.com

Nelson D. Gerundo
Nelson D. Gerundo

 

There are two types of these septic necrobiotic lesions:

Both are sufficient to cause a drop in the survival rate upon stocking in the nursery RAS but the chitinolytic type is apparently even more troublesome at the postlarval stages.

Nelson

Nelson D. Gerundo
Nelson D. Gerundo

 

Dear Narayana Murthy,

Now,  this is what I call a real pathology ... i.e. pathological descriptive terminology supported by documentary photomicrographs from actual commercial vannamei shrimp RAS nursery production run in real-time based on real experience.

Kind regards,

Dr. Nelson Gerundo, D.V.M.

Philippine Professional Board Licensure Regulatory Commission Official Authority to Practice Veterinary Medicine and to Sign a Prescription Note ... License # 002395

https://www.pharmasystems.com/image/cache/data/product_images/PP-8-500x500.jpg

Nelson D. Gerundo
Nelson D. Gerundo

 

Can vannamei shrimp farmers be able to see this lesion by merely looking at the vannamei postlarvae through the plastic packaging bag or while looking through a clear glass container?

Penaeus vannamei  (Postlarva 11) from a shrimp hatchery in the Visayas exhibiting  penetrating localized septic chitinolytic necrosis of one of its periopods (or layman’s terms: walking leg)
Penaeus vannamei  (Postlarva 11) from a shrimp hatchery in the Visayas exhibiting  penetrating localized septic chitinolytic necrosis of one of its periopods (or layman’s terms: walking leg)
 

ANSWER: No … too small to recognize with the naked eyes.

Many small-scale shrimp farmers are unable to see this early warning sign of an impending disaster about to affect their seed stocks upon stocking to their nursery pond or grow0out pond simply because they haven’t got a microscope at the farm, if not, insufficiently trained to operate a simple binocular microscope.

Vannamei postlarvae are very small... how much smaller are their walking legs and swimming legs?

Nelson

Nelson D. Gerundo
Nelson D. Gerundo

 

Septic Necrobiotic Lesion (LEFT)  VERSUS  Aseptic Healed Wound Due to Cannibalism (RIGHT)

Not to be confused with aseptic injury caused by cannibalism in black tiger prawn larvae.

Septic necrobiosis (eroding type) of the periopod in Penaeus vannamei postlarva 11 (LEFT) and Aseptic healed wound on the first antenna of Penaeus monodon - mysis 2 as a result of cannibalism (RIGHT)
Septic necrobiosis (eroding type) of the periopod in Penaeus vannamei postlarva 11 (LEFT) and Aseptic healed wound on the first antenna of Penaeus monodon - mysis 2 as a result of cannibalism (RIGHT)

 

Nelson D. Gerundo
Nelson D. Gerundo

 

What is the difference between the term “Septic” and “Aseptic”?

ANSWER:

SEPTIC - infected with harmful pathogens

ASEPTIC - free from contamination caused by harmful pathogens

Kind regards,

DR. Nelson Gerundo, D.V.M.

Former Official Regional Officer of the European Association of Fish Pathologists (EAFP)

https://eafp.org/

 

 

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