- Animals: fish
- Animal Production: general animal production
- Farm Business Management: new enterprise development
- Sustainable Communities: new business opportunities
Small dairy operations are slowly being converted to larger operations, beef cattle or grain operations leaving behind hundreds of manure pits which are ideally designed and suited for use in the aquaculture industry. This project will evaluate the water quality of abandoned manure pits (abandoned from between 3 and 18 years) to determine suitability for raising fish. Water quality sampling will be conducted over a two year period in all four seasons and include both horizontal and vertical sampling locations in each of three pits. If water quality is determined to be suitable for fish, an evaluation of suitability for fry, fingerlings and broodstock will be conducted as will the grow-out of fish using pond-side tanks. Results of these efforts will be shared with the local farming community as well as local extension personnel and land-use coordinators.
As dairy operations consolidate in the United States, many small farms are converting over to alternative livestock and/or grain operations. This leaves hundreds of engineered manure pits vacant – over two dozen in Outagamie County, WI alone. Most of these pits have been designed to meet standards to prevent leakage i.e., concrete, synthetic lined or clay lined. Once the pit is no longer used, it is normally required to be abandoned and there are regulations for proper abandonment which mostly deals with the liquid and solid waste in the pit. Regulations also allow the pit to be reused including for such uses as aquaculture. In order for the pit to be used for aquaculture, the water contained within has to be deemed suitable for raising fish. The Outagamie County Land Conservation Coordinator has indicated that these pits do not have to be abandoned if used for aquaculture as this will be considered continued farm use.
At the same time that these pits are becoming available, the aquaculture industry is seeing a significant demand for food fish. Live catch of perch from the Great Lakes has been significantly lower in the past three years and the industry cannot ramp up production fast enough. The actual cost for Great Lakes perch fillets has gone from less than $10 per pound in 2013 to over $13 per pound in 2014 and predicted much higher for Lent in 2017. There is a genuine lack of water resources [ponds or indoor Recirculating Aquaculture Systems (RAS)], the ability to permit more outdoor systems (expansive pond culture systems), and there is virtually no one providing feed trained fingerlings for use in indoor (RAS) or aquaponics systems. The aquaculture industry absolutely has to rely on alternatives such as vacant manure pits to solve some of these capacity problems.
This project will focus on three objectives. One, there will be a need to conduct water quality assessments on existing manure pits to determine that chemical parameters present are compatible with fish culture. These assessments will be conducted multiple times in each pond for two years to determine affects of temperature seasonally and will also be conducted as a vertical profile. Here we will need to determine if any of the ponds stratify and isolate water quality top to bottom. We believe that since the ponds have aged significantly since last used, most organic matter will have settled and has digested (converted to inorganic solids, gases or liquid over time). Therefore the oxygen demand should be much less. This project will use three pond settings, one recently abandoned (three years at initiation of study), one that has been unused for 15 years, and one that was drained and will be refilled for the project.
The second objective is to conduct fish studies. Here we will use perch in several alternative situations. Depending on the immediate water quality, perch may be introduced as eggs, fry, or fingerlings. For this project we will either transfer gravid eggs to observe hatch and fry production, stock with fingerlings to obtain feed trained fingerlings for commercial use, or install pond-side grow-out tanks for demonstration of grow-out from four to eight inches in size in one summer.
Finally, we hope to provide former dairy farmers with a good use for the unused manure pit. With the use of the pit as a resource for aquaculture, the farmer will be able to diversify his crop and provide an alternative source of income.