Production of good quality post larvae in shrimp hatcheries is essential for the success of the farms. Quality control parameters are targeted to ensure that the best quality or most robust post larvae reach the farms. Traditional quality control parameters include size in length, weight at a determined age (21 days of culture), fresh water stress test, a physical observation under a microscope to ensure a post larva free of necrosis and or external fouling on their bodies as well as PCR testing for viral disease (Brock and Main 1994). These parameters aim to ensure that healthy and robust post larvae are stocked into the ponds, contributing to a successful harvest.
The first three days after stocking in the farm ponds is the most critical period, as this is the point where post larvae are transferred from a very controlled hatchery environment, to an open environment in which they are exposed to the elements. The transfer process itself can be every challenging and when finally stocked the young animals must work harder to find their food source, as the ponds are much bigger than a larval rearing tank or a nursery.
Hatcheries regularly have a dedicated department or team of people to check quality parameters (Ortiz et al 2008).
While these parameters can be quantified, in practice, it is very difficult to standardize the procedure to arrive at a truly comparable dataset from batch to batch or from one hatchery to another. There is great debate whether or not these sometimes subjective quality control points are indicative of harvest success in the grow-out ponds.
Taking this into consideration, it becomes clear that new tools are required to allow a simple, fast and consistent measurement of stress tolerance under a period of reduced feed intake. We developed an energy reserve measurement to be able to quantify the robustness and strength of the post larvae before they reach the farm.
Here, we present a new quality control parameter to describe robustness based on regulated starvation of good quality post larvae. The energy reserve measurement or ERM, directly measures the energy reserves in the post larvae. The results indicate a clear correlation between diet types and post larva quality.