> For the complete documentation index, see [llms.txt](https://help.fielddoc.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.fielddoc.org/resources/models/oyster-aquaculture.md).
# Oyster Aquaculture
Estimate nutrient reductions using data and algorithms from the Chesapeake Bay Program's Oyster BMP Expert Panel Report.
FieldDoc uses the fixed oyster nutrient-content values approved for this calculator. Users enter oyster counts; the model applies the values shown below.
#### Calculation method
FieldDoc multiplies the number of oysters in each size class and ploidy by the fixed nitrogen or phosphorus content for that class. It sums the class totals, then converts grams to pounds using 0.00220462 pounds per gram.
```
tn_lbs_reduced = sum(animal_count × nitrogen_grams_per_oyster) × 0.00220462
tp_lbs_reduced = sum(animal_count × phosphorus_grams_per_oyster) × 0.00220462
```
#### Nutrient content by size class
| Grams of nitrogen and phosphorus per oyster | | | | |
| ------------------------------------------- | --------- | --------- | ---------- | ---------- |
| Size class | Diploid N | Diploid P | Triploid N | Triploid P |
| 2.25 inches | 0.05 | 0.01 | 0.06 | 0.01 |
| 3.0 inches | 0.09 | 0.01 | 0.13 | 0.01 |
| 4.0 inches | 0.15 | 0.02 | 0.26 | 0.03 |
| 5.0 inches | 0.22 | 0.02 | 0.44 | 0.05 |
| Greater than 6.0 inches | 0.31 | 0.03 | 0.67 | 0.07 |
#### Oyster types
Diploid oysters have two sets of chromosomes. Triploid oysters have three sets and are sterile. FieldDoc applies a separate nutrient-content value to each ploidy and size class.
#### Attribution
The Oyster Aquaculture model estimates nutrient reductions using data and algorithms from the Chesapeake Bay Program's [Oyster BMP Expert Panel Report](https://d18lev1ok5leia.cloudfront.net/chesapeakebay/documents/Oyster-BMP-Expert-Panel-Second-Report.pdf). The Expert Panel was convened in 2015 to evaluate and implement oyster practices as best management practices for nutrient reduction in the Chesapeake Bay.
Jurisdictions within the Chesapeake Bay watershed can include harvested oyster tissue as a nutrient reduction BMP in their watershed implementation plans. Credit for nutrients reduced by oyster practices is attributed to the shoreline segments closest to the harvest location.
### Walk Through of Oyster Aquaculture Model
**Step 1. (optional) connect your model run to an activity\***
\*If you have run the model from within an activity record, the activity will already be connected.
**Step 2. Select practice classification**
Select the oyster practice classification that matches your implementation.
The drop-down provides all classifications available in this model. You can only select one option per model.
Make sure to click the Save and continue button.
**Step 3. Enter number of animal units.**
Enter the number of oysters in this practice's size class and pliody.
**Step 4. Estimated nutrient load reductions**
After entering all inputs, the system returns the estimated nutrient load reductions.
**Step 5. Label your model run**
---
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