Module 1
02.
Lesson 2 : Key Actions in ponds: Sampling and Feeding
This lesson covers the various handling practices around shrimp farming ponds. It explains how to collect and handle shrimp without stress to assess their health status, as well as the different feeding methods and their impacts on welfare and growth.
Why is it important to sample in different areas of the pond?
How can shrimp be handled without causing stress?
What is the benefit of feeding shrimp frequently?
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.
Sampling
Animal monitoring is typically conducted daily in terrestrial farms to assess the health of individuals and identify potential issues. In shrimp ponds, however, the main challenge lies in the brackish water, which hampers visibility and makes it difficult to observe the animals’ behaviour. In this part, we are going to discuss how to realize a good sampling, where in the pond, what indicators can be checked and how to handle the shrimp carefully.
Location
In the video, you can see a farmer entering the pond with a net. He is around the automatic feeder, which is the place where he is sure to get lots of shrimp as they are coming around to eat. We can suppose that the shrimp he will get are the healthiest and biggest shrimp. If it is the only sample, there might be a risk to misinterpret the data. By multiplying the sampling in different locations of the pond, it is longer, but data are more accurate. Sampling for example at the edges or at the exit gate, where the sick shrimp usually go (Pedrazzani et al, 2023) can give a better view of the healthiness of the pond.
Shrimp handling
As shrimp are aquatic animals, it can be stressful to handle them out of the water. When sampling, it is recommended to keep them into water from the pond.
There are 2 possibilities:
- To collect the shrimp and to put them into a net/cage directly into the pond. Then it is possible to observe and release the shrimp as you go along,
- To collect the shrimp and to put them into a basket filled with water from the pond. In that case, it is better to add aeration to avoid shrimp from being stressed.
Indicators
It is important to know what to observe on the shrimp sampled. Pedrazzani and her team (2023) identified several indicators at all stages of shrimp production cycle divided in 4 specific topics: environment, health, nutrition, behaviour.
Here, we chose to focus on health indicators which are linked indirectly to other indicators (e.g. injuries can be caused by social interactions like conflicts or by poor handlings) because that is the one that requires to handle shrimp.
Based on that paper, the FAI academy created shrimp welfare indicators score cards to provide farmers easy to use tables to assess and score shrimp welfare. 10 indicators are described during the grow-out stage with 3 different scores for each of them (Score 1 being a good welfare and score 3 critical for welfare).
Number of shrimp sampled / Frequency
For now, there are no recommendation on the number of shrimps to sample or the frequency. However, based on FAI experience, farmers can do 30 shrimp in 10 minutes. This section will be updated as soon as we have more data.
Feeding
Feeding methods
Feeding can be done either by automatic feeders or manually.
Automatic feeders: The feeder can be scheduled to distribute the feed with a determined frequency during the day and/or the night. It can also be “demand feeders” which are connected with hydrophones and based on acoustic sensing. That means that they record the clicking sounds of the shrimp. In that case, the feed is distributed whenever the shrimp are hungry.
It is also possible to have several trays in the pond and to add feed inside. It is important to have enough feed trays to ensure that all the shrimp can eat. Nunes (2001) recommended to use 25-30 trays per hectare, separated by 20 meters.
Manual feeding: Feed is distributed in the pond on the volley thanks to a boat. When using manual feeding, it is important to distribute the feed everywhere in the pond to improve the chances that all the shrimp can eat.
Feeding frequency
According to the literature, shrimp feed in small amounts (Darodes de Tailly et al., 2021), grasping many pellets at once (Kawamura et al., 2018), and repeatedly over time (Reis et al., 2021; Simon et al., 2021). Thus, it is more consistent with shrimp behavior to distribute feed frequently throughout the day. Nevertheless, the optimal feeding frequency is not well known. For some authors, growth and feed intake are improved when feedings are multiple (Carvalho & Nunes, 2006; Nunes et al., 2019; Robertson et al., 1993; Ullman et al., 2019a, b); for others, more than four feedings per day could lead to a loss of stimulation and reduce overall intake (Bardera et al., 2018). Ullman et al. (2019b) found that increasing feed by 15% while maintaining the feeding frequency at twice per day had no effect on shrimp growth, whereas keeping the same amount of feed but increasing the feeding frequency to six times per day improved growth.
More frequent manual feeding is labor-intensive, and automatic feeders require a significant initial investment. If automatic feeders are installed on the farm, it is important to monitor water quality even more frequently, as a greater amount of feed can be distributed, which may alter water quality. Further research on feeding behavior could provide useful information and allow for better adaptation of feeding strategies.
Feeding frequency will also depend on the level of farming intensification. In extensive production, shrimp are nourished by the natural environment and may require less frequent feeding with formulated diets. Frequency should therefore be adjusted according to gut fullness. In addition, it is important to avoid feed wastage in order to minimize environmental impact.
Stay tuned, more results coming soon…
Feeding time
It is not even clear what the preferred feeding time is. For some authors, there is no preferred feeding schedule if other conditions are appropriate (Reis et al, 2021), for some others, the preferred feeding time is seven hours after light onset (Pontes et al, 2006) and for others there is a nocturnal feeding pattern as shrimp are more active by night (Santos et al, 2016; Ullman et al, 2019). Again, more research is needed to determine the feeding behaviour of the shrimp and the preferred feeding time.
What to remember
a) Sampling
• Location: Sampling in shrimp ponds should be diversified across various areas (e.g., feeder, pond edges) to ensure comprehensive data representation.
• Shrimp Handling: Handle shrimp carefully to minimize stress; consider options like keeping them in water during sampling to maintain their health.
• Indicators: Focus on health indicators, which reflect overall shrimp welfare; use standardized score cards for assessment.
• Number/Frequency: Current data suggest that it is possible to sample 30 shrimp in 10 minutes, pending further data.
b) Feeding
• Feeding Methods: Use automatic or demand feeders for efficient feed distribution.
• Feeding Frequency: Optimal feeding frequency varies; frequent feeding may enhance growth but requires careful monitoring of water quality.
• Feeding Time: Ideal feeding times are debated; nighttime feeding might be beneficial due to shrimp activity patterns.
These summaries highlight key practices for effective sampling and feeding management in shrimp farming, emphasizing welfare and productivity considerations.