పరీక్ష పరిస్థితులు

పరీక్ష నవంబర్ 2022 నుండి మార్చి 2023 వరకు జరిగింది.

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అనుబంధంలో వివరించిన మా ఫిష్ వెల్ఫేర్ స్పెషలిస్ట్ నుండి బరువు-ఆధారిత డిజైన్‌ను ఉపయోగించి చికిత్స చేసే ఫారమ్‌లోని ఫీడ్ పరిమాణం (తగ్గిన దాణాతో) నిర్ణయించబడింది.

The feed quantity for our control farm was decided using the “blind” feeding method, where supplemental feed is introduced up to the point that any increase would result in not all the feed being eaten by fishes—this is the method typically implemented by farmers. Where there were uncertainties with the blind feeding method, the farmer who owned these farms and another Alliance for Responsible Aquaculture farmer were consulted.

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Data Collection

Farms were observed twice daily—once in the morning (between 6:30 and 8:30 AM) and once in the evening (between 04:30 and 06:30 PM).

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The full raw data can be found here.

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External and Confounding Factors

Our test results may have been affected by the following external factors, details of which are provided in the Appendix.

• Proximity of our control farm to a rice mill, active since December 16, 2022: Rice debris blowing into the farm from the mill may have increased nutrient levels, and consequently affected the phytoplankton levels.

• Disease outbreaks in both our farms: Although we were implementing disinfection protocols, diseases are very common in Andhra Pradesh carp farming. Fortunately, this outbreak was fairly mild, as we were able to identify and treat the disease quickly

Application of fertilizers and sanitizers during the test to both farms, albeit in equal quantities at the same time.

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Results and Implications

The treatment farm was, on average, given 17% less supplemental feed (though it varied some over time) than the control farm. On average, the treatment farm had 22% less of Chlorophyll a—a naturally-occurring pigment that is a strong signal of phytoplankton population density—than the control farm (with a standard deviation of 39%).

 

Our analyst ran statistical models on our data in order to directly assess whether the hypothesis holds (“reduced supplemental feed would lead to better phytoplankton and dissolved oxygen levels than the control, and growth rates will be the same”). These models took into account differences in morning and evening measurements as well as the different seasonal periods (November 2022–March 2023).

 

These were the main takeaways:

• The levels of Chlorophyll a and phycocyanin, which are strong proxies for phytoplankton levels, were reduced in the treatment farm.

• Fishes’ weight showed no significant correlation with the treatment, implying that treatment had no effect on their growth.

• Turbidity positively correlated with treatment, which was an unexpected result.

• DO levels showed no significant correlation with treatment, implying that even though the treatment reduced phytoplankton levels, this did not translate into improved DO levels.

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For details, please see the Appendix.