Progress report for FNC25-1481
Project Information
Team Proposal between Mulberry Aquaponics LLC and Northey Farms LLC
Mulberry Aquaponics: (2278 Center Ave, Stoughton WI, 53589)
Peter Shep (Co-owner Mulberry Aquaponics LLC) e-mail: mulberryaquaponics@gmail.com
Bachelor of Science: Biology (Freshwater Ecology/Marine Biology) University of
Wisconsin - Whitewater
Master of Science: Freshwater Technology (Aquaculture Nutrition in Early Life Stages)
Ph.D. student (currently) working on sustainable aquaculture breeding and nutrition
University of Wisconsin - Milwaukee
Peter Shep will be the principle investigator (PI) for this project. He has extensive
experience managing yellow perch breeding at the University of Wisconsin - Milwaukee,
and has support for this project from his adviser Dr. Dong Fang Deng at the
University of Wisconsin - Milwaukee who specializes in yellow perch aquaculture
research. Peter has a proven record for system engineering, breeding yellow perch,
and producing fingerlings in recirculating aquaculture systems (RAS). He has created a method to propagate yellow perch utilizing a cost-effective and sustainable method by using low energy pumps for RAS which could potentially be operated off-grid using renewable energies. This technology has been used to produce and sell over 20,000 yellow perch fingerlings to schools, ponds and other aquaculture businesses.
Mulberry Aquaponics was created in 2021 in a defunct dairy barn as a pilot run to test this yellow perch RAS breeding method. The facility has out-of-season spawning capability, housing four different temperature zones as well as 21 RAS aquaculture tanks with a volume of over 16,000 gallons. It currently has a
six-tank (dual-triplicate) RAS system to aid in research.
This facility was discussed on the Larry Meiller show entitled "Taking a tour of Wisconsin's Aquaculture Industry" in 2023: https://www.wpr.org/shows/larry-meiller-show/taking-tour-wisconsins-aquaculture-industry, it was the main topic of the "Wisconsin Seagrant Decision Makers Tour" in 2024: https://www.seagrant.wisc.edu/news/a-fish-farm-field-trip-for-wisconsin-decision-makers-highlights-challenges-and-future-of-aquaculture/, and it recently was featured on a news story by Spectrum News 1 Wisconsin entitled "Fish Farms Refine Process to Maintain Fish Supply for Restaurants and Markets": https://spectrumnews1.com/wi/milwaukee/news/2024/10/26/mulberry-aquaponics-hatchery-fish-farm
Northey Farms
David Northey (Owner Northey Farms) e-mail: noresk42@yahoo.com
Bachelor of Science: Biology (Animal Science) University of Wisconsin - Madison
Master of Science: Biology (Endocrinology) University of Wisconsin - Madison
David has been operating more than 20 acres of outdoor yellow perch breeding ponds
at Northey Farms for over 30 years. Currently, he is one of the few main providers
of yellow perch fingerlings in Wisconsin. He has been responsible for innovation in
yellow perch pond production.
David will be CO-PI, and share the work-load for this project.
Consolidating multiple farming sectors into large commercial farms have left small farmers (many with food producing experience) seeking other areas of employment. Yellow perch fingerling production could provide a new avenue of agriculture production and a commodity that is in extremely high demand (>$30 million/year market gap since the commercial fishing crash of the mid-1990's) (FAO landings data 2024).
Perch farming has a systemic problem. Yellow perch farmers tend to gravitate towards the ease of running tier-2 (grow-out) farms which purchase fingerlings from tier-1 farms that breed them. The reason is that operating a tier 1 fish farm is challenging. The issue with this is that there are an abundance of farms growing out fingerlings and almost no one breeding or creating them. This problem has led to a farming industry with unbelievably high demand and almost no supply.
My farm ran a marketing analysis for fingerlings in 2024 that we bred and we received e-mails from tier 2 farms indicating an astonishingly high market demand for these fish. Even if the tier 1 farms can satiate the market for food fish farms they will never appease the market for pond stocking in the Midwest. Production limits are open ended.
This proposal will focus on the propagation of yellow perch in a low-cost off-grid portable aquaponics hoop-house. The goal of this research project is to demonstrate that an off-grid hoop-house could produce similar yields of yellow perch fingerlings as a specialized indoor RAS and outperform a specialized yellow perch propagation pond.
This would show that yellow perch could be propagated in a self sustaining hoop-house at a low cost.
The trial will include 3 "treatments" or "facilities":
- Off-grid yellow perch propagation hoop-house RAS: Located at Northey
Farms LLC. This is a solar and wind powered hoop-house with three 300 gallon
tanks showing results in triplicate for a designed experiment, and 240 watts of
water and air pumping power to recirculate the water. (6 egg ribbons) - Two on-grid insulated yellow perch propagation RAS: Located at both
Mulberry Aquaponics LLC and Northey Farms LLC. This is an on-grid yellow perch
propagation RAS with three 300 gallon tanks each, identical to the off-grid RAS.
These systems utilize the same 240 watts of water and air pumping power. (12
egg ribbons: 6 ribbons x 2 farms) - One commercial propagation pond: Located at Northey Farms LLC. This is a
0.2 acre commercial production pond which has been used to produce yellow
perch. (6 egg ribbons)
The research trial will commence in middle May-June to ensure warmer temperatures in Wisconsin.
Twenty-four yellow perch egg skeins will be fertilized and incubated for ten days in an incubation system at Northey Farms LLC. Typically over 300 egg skeins are fertilized each year at Northey Farms LLC, so only the best quality egg ribbons will be chosen for this research to ensure consistent egg performance. At ten days each egg ribbon will be cut into twelve pieces and each piece weighed to ensure a similar number of fertilized eggs will be placed into each tank/pond using a total of 6 egg ribbons per treatment. The egg ribbons will be vigorously aerated for 24 hours to ensure a passive unbiased hatching into each tank/pond.
All RAS treatments will use an identical automated feed regimen of Otihime B1 larval weaning feed (Marubeni Nisshin feed company Tokyo, Japan) as well as an automated dosing of live-feed (90% Hatch Brine Shrimp - Salt Lake City Utah U.S.A) through 40 days post hatch (DPH) to demonstrate successful clearing of the mortality spikes of yellow perch larvae at 7-12 DPH and 23 - 29 DPH. Loss of yellow perch after 40 DPH is minimal.
The pond treatment will follow a process used by Northey Farms LLC, which uses urea and alfalfa-meal to promote native zooplankton populations within a pond. The fish are stocked, and are allowed to feed on natural zooplankton for 40 days and then harvested by using a seine net to collect all surviving fish at 40-DPH. At 40-DPH all fish will be collected from each treatment and statistical analysis will be used to identify differences in survival, weight, and total production.
After data collection for presentation, fish will be assessed and sold.
Established wholesale yellow perch prices in USD are (0.33/2-4" fish, 1.10/4-6" fish, >3.50/6"+ fish)
- Objectives: The objectives of this initial round of research is to:
- Demonstrate the feasibility of using an off-grid hoop-house to propagate yellow
perch compared to conventional systems. - Identify the hidden expenses of propagating yellow perch in an off-grid system.
- Identifying the hidden problems with propagating yellow perch in an off-grid
system. - Investigate a pathway to creating a low cost, sustainable yellow perch fingerling
market.
Secondary future objectives are to initiate a research process to identify other sustainable inputs to off-grid yellow perch propagation. These being:
- Creation of a sustainable domesticated yellow perch larval feed
- Inclusion of an aquaponics with this system to remove excess nutrients
- Investigation into the use of a hybrid RAS and pond propagation system
Cooperators
- - Producer
Research
Northey Farms and Mulberry Aquaponics LLC initiated the 2025 spring spawn of yellow perch (Perca flavescens) by allowing pond water temperatures to rise naturally, thereby stimulating reproductive behavior in the broodstock populations. Spawning occurred during the third week of April. Fertilized egg ribbons were collected and incubated in well water for 10 days. Upon hatching, the ribbons were manually dispersed to release 0-day post-hatch sac-fry into their respective rearing tanks.
Each rearing tank was a 500-gallon fiberglass unit filled to a depth of approximately 16 inches. Tanks were equipped with an independent in-tank biofilter system containing biomedia pre-acclimated to 5 ppt salinity. Approximately 200,000 sac-fry were stocked per tank.
Live feed consisted of Artemia nauplii sourced from the Great Salt Lake (Utah, USA), which were decapsulated daily using the method described by Sorgeloos (1977). The Artemia were hatched and fed to the fry using an automatic timer that dispensed roughly 10 grams (dry weight) of cysts per day. The nauplii ranged in age from 18 to 28 hours throughout the 10-hour daily feeding period.
In addition to live feed, a dry microdiet (Otihime, Marubeni Nisshin Feed Co., Tokyo, Japan) was administered. Feeding began with particle sizes of 250–360 µm and was incrementally increased every 10 days to match fish growth. At 20 days post-hatch (DPH), live feeding was discontinued, and the fish were maintained exclusively on the dry feed regimen.
By 35 DPH, the yellow perch fry demonstrated a 99.9% survival rate and were fully weaned onto dry feed. At 60 DPH, fish reached a marketable juvenile size of 2–4 inches, marking the end of the larval rearing stage. At this point, fish were graded and redistributed according to the prevailing production strategy of the farm.
All tanks were cleaned every four days throughout the rearing period.
As part of this project, a 24' × 20' hoophouse was constructed on flat terrain with the goal of replicating the rearing procedure described above in a semi-enclosed, energy-efficient environment. However, due to delays in material delivery, construction was completed after the 2025 spawning season. Consequently, the system was not used for sac-fry rearing in 2025, but is being prepared for implementation during the 2026 spawn. The methods described here reflect the infrastructure setup and interim testing carried out in 2025.
Two 500-gallon fiberglass tanks were installed inside the hoophouse and filled to a depth of 16 inches. Standalone in-tank biofilters were placed in each unit; however, the biomedia did not have adequate time to acclimate prior to stocking. To support energy independence, a portable solar panel array was installed and wired directly to the hoophouse electrical system. Testing showed that under full sunlight, the system generates power in excess of the daily energy demands of the water pumps and aeration units, enabling continuous operation. On overcast days, the system can sustain operations for approximately 27 hours without recharging.
To supplement solar energy on low-light days, a portable wind turbine is currently under construction and will be integrated into the power system prior to the 2026 season. In 2025, the two hoophouse tanks were stocked with juvenile yellow perch in one tank and bluegill (Lepomis macrochirus) in the other. These fish serve as a biological load to help establish and condition the biofilters ahead of next year’s sac-fry rearing. They also help farmers understand the bio-load that a hoophouse aquaponics fish rearing system can handle.
Additionally, the farm is incorporating aquaponics systems into the hoophouse design. These systems are being engineered to operate without increasing the energy demand of the overall system. Collectively, these efforts aim to prepare the hoophouse for full integration into yellow perch larval production in the 2026 season.
The indoor yellow perch breeding procedure utilizing standalone in-tank biofilters demonstrated performance comparable to established commercial production systems. In 2025, Northey Farms LLC achieved consistent, repeatable yields of approximately 13,000 to 14,000 market-size yellow perch per 500-gallon tank, while maintaining energy usage below 50 watts per tank. These results suggest that low-energy, in-tank biofiltration systems can match the production efficiency of traditional systems, offering a cost-effective and scalable solution for yellow perch rearing.
In contrast, Mulberry Aquaponics experienced a complete loss of the 2025 yellow perch cohort due to critical management oversights. Staffing and training issues led to lapses in essential care procedures, underscoring the importance of skilled labor in early-stage aquaculture operations. Measures are currently being taken to address these training gaps to ensure success in the 2026 production cycle.
Although the newly constructed hoophouse was not fully operational in time for the late April 2025 spawn, progress toward system integration is ongoing. Structural improvements, biofilter conditioning, and renewable energy testing are currently underway. Early assessments of the solar power array indicate that it exceeds the electrical demand of the system on sunny days, with up to 27 hours of reserve power available during overcast periods. A complementary wind turbine is also being developed to bolster off-grid energy resilience.
These results support the continued development of this modular, energy-independent rearing system. With final system adjustments planned in the coming months, the hoophouse is expected to be fully operational for the 2026 spawning season. The goal remains to demonstrate a robust, low-energy indoor rearing protocol adaptable to variable spring conditions in Wisconsin.
Educational & Outreach Activities
Participation Summary:
On Tuesday, June 24th, Wisconsin Sea Grant—led by Food-Fish Outreach Coordinator Sharon Moen—visited Northey Farms LLC as part of a tour and workshop event. The group also visited Pleasant Springs Perch Inc., another farm with which we have an ongoing consulting relationship. The visit included a hands-on workshop, fish fry, and a journalistic write-up by a Sea Grant staff writer, who interviewed farm personnel, toured the facilities, and observed demonstrations of the low-energy yellow perch breeding system.
Participants were also shown the newly constructed hoophouse, which is currently housing larger fish to help establish the system and acclimate the biofilters. While it was not ready in time for the 2025 spawning season, it is fully functional and expected to be used for yellow perch larval production in 2026.
During the visit, we also presented details about the Sustainable Agriculture Research and Education (SARE) grant we received and explained our phased approach to implementation. Three additional outreach events are currently in the planning stages. The first will be a presentation for farm interns on July 31st. The second will be a SARE-funded field day and fish fry tentatively scheduled for the second week of August. Finally, during the first week of September, we will provide yellow perch as a featured food item at a local food truck during Harbor Fest in Milwaukee, held adjacent to the University of Wisconsin–Milwaukee School of Freshwater Sciences.