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When Things Go Wrong: Addressing a Flaw in our Stocking Density Monitoring

This post is a little shorter and more narrative than our usual blog style, but we are interested in exploring publishing more, shorter posts that give an insight into our work. Feel free to reach out or leave a comment below if you'd like to see more or less posts like this going forwards.

Like other farmed animals, farmed fishes suffer when they are placed in overcrowded conditions: Research has consistently shown that poor stocking densities can lead to numerous welfare issues, including stress, susceptibility to disease, and aggressive behaviors.

For this reason, part of FWI's current farmer ask is to maintain a fish stocking density not exceeding 3,000 fish per acre, which is what our research suggests to be best for fish welfare while also considering the economic feasibility. To monitor compliance, we gather data on two fronts: the size of the farmers' earthen ponds and their stocked fish count. By dividing the number of fish by the pond area, we calculate the stocking density.

However, the accuracy of this calculation hinges on the accuracy of the data provided. A recent review, initiated by a vigilant member of our team (shoutout to Paul here), revealed a significant discrepancy: Many farmers were reporting the total size of their property, which, in most cases, is larger than the actual size of the ponds. This oversight led to a miscalculation of stocking densities, which, in the case of 58 partner farms, resulted in densities exceeding our recommended limits.

To rectify this, we are using Google Earth to more accurately determine the actual area of the farms' ponds (assuming a consistent depth of approximately 2 meters). Additionally, we are enhancing the reliability of our fish stocking data by verifying the stocking receipts provided by the farmers.

A screenshot of our new measurement system for pond size. Previously, this farm was reported to us as being 7 acres in area. Google Earth reveals that the actual acreage is roughly 1 acre smaller.

However, obtaining precise data is only a part of the broader challenge, as ensuring farmer compliance remains a significant hurdle. In particular, we expect that many farmers will be reluctant to reduce their fish densities without additional incentives, having operated successfully at higher densities. Our team is currently exploring strategies to incentivize compliance, and once a viable solution is identified we will update our programs accordingly.

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