SHORT COMMUNICATION: Synchronous molting of Pacific white shrimp (Litopenaeus vannamei) postlarvae by reducing salinity: A strategy for acclimatization before transport

Abstract

The study assessed a method for synchronizing molting in Pacific white shrimp (Litopenaeus vannamei) postlarvae (PLs) by lowering salinity to prevent molting during the transportation and storage of PLs. For this purpose, 96,000 L. vannamei (PL15 average length of 9.1 ± 1.2 mm) were randomly distributed into eight experimental units (12,000 per unit/60 PLs L⁻¹), composed of 200 L circular polyethylene tanks, and subjected to two treatments: a control group without acclimatization and a treatment group, in which the PLs were acclimated from 35 ‰ to 15 ‰ salinity for 24 h. During the experiment, 30 PLs were collected from each experimental unit every 6 h over a period of 66 h to determine the molting stages. Acclimatization to salinity led to a significantly higher number of PLs in the final pre-molting stage (F-PrM). A decrease in water salinity led to a significant increase (p < 0.05) in the occurrence of PLs during the molting stage. The molting process was similar for both treatments. Salinity impacted the quantity of PLs in the F-PrM stage but did not accelerate the molting process. The number of complete molt cycles was consistent across the treatments (36–42 h). As a result, it is advised to harvest and transport L. vannamei PLs between 42–48 h from the start of acclimatization to avoid peaks of PLs close to molting, specifically in the F–PrM stage. This precaution can help prevent PLs from molting during transportation and enhance their survival rate.