Letter W

Water Exchange (Water Renewal): The act of replacing a portion of the pond water to dilute metabolites (like ammonia) or correct parameters.

Water Quality: The set of physical, chemical, and biological characteristics of water that affect the culture performance.

Water Use Permit: The legal authorization required to withdraw water from a water body (river, well) or to discharge effluents.

Wheel Line: A type of aerator consisting of paddles mounted on a long axle, often driven by a motor on the pond bank.

White Feces Disease (WFD): A syndrome in shrimp, of complex or unknown origin, characterized by white fecal strings and reduced growth.

White Spot Syndrome Virus (WSSV): A highly lethal virus that causes White Spot Disease in shrimp.

Withdrawal Period: The mandatory minimum time between the last application of a drug and harvest, to ensure no residues remain in the flesh.