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).
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
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.
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.
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.