Module 1
03.
Hatchery in Action: Movements, Feeding, and Observations
This lesson covers shrimp handling at the hatchery, focusing on gentle methods to minimize stress, observing their behavior, and the impacts of these practices on their welfare.
How can hatchery practices affect shrimp reproduction, health, and overall welfare?
What are the consequences of stress and handling (such as eyestalk ablation or transfers) on broodstock shrimp?
How can observing shrimp behavior and adjusting rearing conditions (light, feeding, transport) help improve hatchery management?
What you will find in this lesson
References such as “Dupont et al., 2015” or “Martin & Durand., 2015” refer to the authors of the scientific publications on which the presented information is based. They ensure the accuracy and traceability of the data.
Eyestalk ablation
Eyestalk ablation has been used since 1970 and is still a common method in commercial hatcheries. It involves the removal or constriction of one or two eyestalk through cutting, cauterizing or tying, to reduce the level of gonad inhibiting hormone. This technique leads to more frequent and predictable peaks of ovarian maturation and spawning. However, removal of the optic ganglia has high impact on animal welfare and on shrimp physiology. Molting is also impacted by the ablation. In fact, following ablation, molting increases, leading to exhausted and stressed females. In an experience made in 2008 (Sainz-Henandez et al, 2008) the duration of the molting cycle for bilaterally ablated shrimp was 10 days, 17 days for unilaterally ablated and 24 days for the non-ablated. Furthermore, mortality was higher in unilaterally (35%) and bilaterally (68%) ablated shrimp than in untreated shrimp (2%).
In addition, Zacarias proved that ablation has other impact not only on broodstock but also on eggs and nauplii. With this study, some producers decided to stop the ablation and are happy with their production. It is the case of a producer in Central America who adjusted the male-female ratios and increased the number of broodstock females to compensate the expected drop in production (https://www.globalseafood.org/advocate/seajoys-ablation-free-shrimp-answers-emerging-welfare-concern/).
Sainz-Hernández, J. C., Racotta, I. S., Dumas, S., & Hernández-López, J. (2008). Effect of unilateral and bilateral eyestalk ablation in Litopenaeus vannamei male and female on several metabolic and immunologic variables. Aquaculture, 283(1-4), 188-193.
Observation in the water
Compared to the pond where the water is very turbid, it might be easier to observe the shrimp behaviour in the hatchery. When observing the shrimp, use preferably orange/red light with high intensity as it is less stressful for the shrimp and less disturbing (Pichon et al, 2025). Swimming and feeding behaviours are interesting to observe in the hatchery. As described in the paper of Pedrazzani (2023) and presented below, animals should either be at the bottom rather stopping, walking or feeding, or in the water column, normally swimming. If you observe many animals with irregular swimming or crowding of shrimp in certain parts of the tank, that can indicate some issues.
Concerning the observations while feeding, in the hatchery, the shrimp can be fed manually or with demand feeders. As for the grow-out ponds, more research is needed to know more about shrimp feeding behaviour to determine the best feeding frequency and the preferred feeding time. Nevertheless, it is easier to observe feeding behaviour in the hatchery where water is clearer. When feeding, most animals should react quickly by moving to the newly offered food. Again, if most animals do not react, that means there is something going wrong in the tank.
The table below compares 2 studies: one from Reis on the influence of lights on growth, water quality and zootechnical parameters and the other from Pichon, discussing what colors and intensity of lights are stressful for shrimp and what colors can be used for observation. Thus, it is important to notice that the purposes are clearly different. Green appears to be better for certain parameters (particularly for algae growth) but red/orange with high light intensity are more adapted to observe shrimp.
Below is an observation of one and then two shrimps with red light in hatchery, behaving normally and not trying to escape from the light.
Observation out of the water
The same health indicators as in the grow-out pond can be observed on the shrimp in the hatchery.
When observing the shrimp, and as seen before, it is better for the shrimp to observe them with a red light (watch the video below). Furthermore, keep the shrimp out of the water as short as possible.
Transfer from one tank to another
One of the main reasons to move shrimp from one tank to another is for spawning. In that case, shrimp are caught with a net, and farmers observe if females are ready to spawn. As seen previously, it is important to manipulate the shrimp gently and to use an orange or red light to observe them outside of the tank. Shrimp can be transferred in a variety of ways, but it is essential to maintain them as much as possible into water to minimize the stress. Furthermore, pay attention to the water parameters between the two tanks to avoid additional stress for the shrimp.
Transfer from the pond to the hatchery
Some of the hatcheries select their broodstock directly in the farm. In that case, shrimp are transported to the hatchery later. During this transfer, it is important to have a low density of shrimp and enough oxygen in the container. Furthermore, be careful of the movement of the boat/truck/car to avoid high movements of water.
What to remember
- Eyestalk ablation, used since the 1970s, increases the frequency and predictability of spawning but has serious negative impacts on shrimp welfare and physiology — causing stress, exhaustion, accelerating molting cycles, and causing higher mortality. Alternatives, such as adjusting male-to-female ratios, have shown successful production without ablation.
- Behavioral observation is easier in the hatchery thanks to clearer water.
- Red or orange light at high intensity is recommended because it is less stressful and it enables better observation.
- Abnormal behaviors — such as irregular swimming, crowding, or lack of response to food — may indicate welfare or water quality problems.
- Feeding can be done manually or with demand feeders. Observing feeding behavior remains an important indicator of health and welfare.
- During handling and transfers, it is crucial to:
- Keep the shrimp out of the water as little as possible;
- Handle them gently;
- Maintain them in water during movements to minimize stress.
- During transport (from pond to hatchery), ensure low stocking density, adequate oxygen, and avoid excessive movement of the water to reduce stress and mortality.