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Hey there,
We hope you’ve had a great month! In this newsletter, we spotlight our welfare interventions for farmed Indian major carp.
Specifically, we dive into the welfare indicators we use in our on-ground work in India. Our efforts to improve these welfare indicators, channeled through the Alliance for Responsible Aquaculture (ARA), demonstrate why direct collaboration with farmers may always be central to our impact.
That’s all for now! If you have feedback or questions, please reply to this email—we'd love to hear from you.
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Have a great week!
Upasana Sarraju
Communications Lead
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The Vitality of Water Parameters
Water, while mostly transparent, reveals its quality in chemical cues. Common indicators like dissolved oxygen, pH, and ammonia levels become more than mere numbers: dissolved oxygen levels showcase the water's life-supporting capability; pH outlines its neutral, acidic, or alkaline nature, and ammonia levels signal the presence of organic activity (among other things). Proxies like these together can potentially signify fishes' health, well-being, and stress levels.
When farmers join the ARA, they agree to uphold evidence-based benchmarks for improved welfare in their farms. One vital benchmark pertains to water quality parameters. Some of these parameters can significantly and immediately impact the welfare of fishes:
- Dissolved oxygen
- pH
- Ammonia
- Turbidity
- Primary productivity
These critical parameters are closely monitored during our field team's weekly/monthly visits to farms. When one or more parameters lie outside the range required for adequate welfare, the discrepancies are rectified with tailored recommendations in each instance.
Details of these reactive efforts are available in our Water Quality Corrective Actions document.
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Our Program Associate Nikhil cleans water sensors that help him record multiple water parameters. Several steps, including wiping down the devices, are followed to prevent water contamination, measurement errors, and inconsistencies.
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Aquatic Respiration: Optimizing Dissolved Oxygen
Of all water parameters we have been monitoring in recent years, dissolved oxygen currently demands our highest attention.
Our 2023 research efforts unfortunately indicated that many farms often don't maintain sufficient dissolved oxygen levels, especially during the summer and monsoon seasons. One of the primary factors causing these variations is likely the unchecked growth of phytoplankton. These minuscule water organisms can disrupt oxygen equilibrium and lead to fishes' stress, often for prolonged periods of time.
We delve into the relationship between dissolved oxygen and fish feed, as well as a small-scale test of a potential intervention in previous blogposts.
We continue to develop our understanding of the complex and delicate science behind maintaining optimal dissolved oxygen levels in farms. More on upcoming research plans soon!
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FWI team members Haven (second from left) and Paul (fourth from left) examine samples of pelleted fish feed used in many aquaculture farms across Andhra Pradesh, India.
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The Boundaries of Stocking Density
Stocking density—the number of fishes living in a unit area of a farm—is another key welfare-impacting parameter that we provide clear guidance on. All ARA farmers commit to rearing no more than 2000–3000 fishes/acre in a growout farm (where fishes in their later stages of the lifecycle are reared until they are sold).
Like every species, Indian major carp require specific spatial parameters in farms for optimal health and behavior. Overcrowding these confines may lead to reduced water quality, increased frequency of injuries, notable behavioral changes, and heightened susceptibility to illnesses.
The converse holds true as well: reasonable and optimal stocking densities in farms can improve and maintain better welfare and health of the fishes.
While research on the stocking needs of Indian major carp has been sparse, our team of fish welfare experts regularly updates our guidelines based on new findings and literature.
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Overcrowding can lead to a myriad of stresses for fishes, ultimately affecting fishes' ability to fight against disease outbreaks. Pictured here is a deceased fish, displaying signs of red spot disease.
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Metrics for a Fuller Picture
In every visit to a farm, our field staff observe many other welfare indicators for comprehensive understanding of a farm's welfare status, including:
- weather conditions
- spread of vegetation in and around the water
- behaviors like air gulping, tail splashing, and lateral swimming
- disease symptoms
- mortalities
- water color
- water temperature
- and more!
You can find an example of our complete datasets, including all the parameters we measure, on our FWI's Full First Year of Measurement Data page.
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We frequently collect water samples from farms for deeper analysis in our field-based laboratories. Here, the water appears green, likely indicating the presence of more phytoplankton than is ideal for fish welfare.
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Other News in Fish Welfare
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Know of other upcoming events or interesting news? Feel free to send them over, and we’ll include them next time!
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A Rohu fish. Credit: H.T.Cheng/iNaturalist
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Rohu fishes (Labeo rohita) have a well-developed olfactory system, which helps them detect food, toxins, and other chemicals in the water. Using an organ called the olfactory rosette, Rohu fishes can also sense when a nearby fish has been injured or attacked, by "smelling" chemical compounds released by the injured individual!
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