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Aquaponics: Comparing Walleye & Tilapia Production
Chris Hartleb Department of Biology
Northern Aquaculture Demonstration Facility Aquaponics Innovation Center
Aquaponics
• Aquaponics is an integrated, soilless system for raising fish and plants.
• Benefits: • Sustainable and natural • Free of pesticides, herbicides and chemical
fertilizers • Highly efficient • Conservative uses of resources, water, space and
labor • Produces both a protein and a vegetable crop
from one integrated system • Continuous production of food 365 days per year
Aquaponics Future
“There is a lack of scientific literature when it comes to aquaponic experiments on large-scale and during long-time sequences. Moreover, many experimental setups published are small-scale without replicates. Experiments covering bigger production systems exist, but they are performed by private research centers or companies, whereby confidential findings are not always made accessible to third parties.”
Economic Considerations
• Tilapia fillet: $2 - $4 per pound (retail) • Walleye fillet: $9 - $16 per pound (retail)
Aquaponics Innovation Center Montello, WI
UWSP-Aquaponics Innovation Center
Nelson and Pade, Inc.® Demonstration
Greenhouse
Aquaponic Systems
Fish tanks
Clarifier (solids filter)
Mineralization tanks
Raft tank Water pump
Degassing tank
Air pump
Overview of Systems
Fish Culture
Clarifier, Mineralization, Bioreactor & Degassing
Plant Culture
Tilapia Culture factor Range
Temperature 64 - 90oF (17 - 32oC)
Dissolved oxygen 3 – 10 mg/L
pH 7 – 8
Ammonia-N 0 – 0.04 mg/L
Nitrite-N 0 – 0.8 mg/L
Hardness 50 - 350 mg/L
CO2 0 – 30 mg/L
Walleye Culture factor Range
Temperature 68 - 75oF (20 - 24oC)
Dissolved oxygen 5 – 6 mg/L
pH 6 – 9
Ammonia-N 0 – 0.02 mg/L
Nitrite-N 0 – 0.2 mg/L
Hardness 50 - 350 mg/L
CO2 0 – 10 mg/L
Why it Works • Optimal ratio between fish and plants
– Balance between fish nutrient production and plant uptake – Feeding rate ratio
• 60-100 g/day/m2 for leafy greens grown on rafts • Right balance is needed based on:
– Type of fish – Plant growth platform – Type of plant (leafy vs fruiting) – Chemical composition of water
• Controlled environment agriculture = year-round production
Fish Plants
Phosphorus Phosphorus
Manganese Manganese
Copper Copper
Iron Iron
Potassium Potassium
Calcium Calcium
Magnesium Magnesium
Zinc Zinc
Cobalt Boron*
Selenium Molybdenum*
Iodine Sulfur*
Protein Nitrogen
Tilapia Growth
Market size
Walleye Growth
Variability in Growth
Market Considerations
• Tilapia, 1½ pounds = 680 grams – Projected fry to market = 297 days (10 months)
• Walleye, 1 pound = 454 grams – Projected fry to market = 1 year 10 months
Tilapia Walleye
Stocked (Harvest goal)
164/system (0.5 lb/gallon, Total 492)
166/system (0.42 lb/gallon, Total 498)
Survival 99% 81%
% Fillet size 41% 1½ pounds
14% ½ pound
Pounds of fillet 80 20
Price/pound of fillet $4/lb $9/lb
Actual value $320 $180
Estimated value 193 lb of fillet = $773 116 lb of fillet = $1,044
Plant Production (Yield)
0200400600800
1000120014001600
Tota
l yie
ld (g
)
Kale
Tilapia Walleye
0.00
500.00
1000.00
1500.00
2000.00
2500.00
3000.00
Tota
l yie
ld (g
)
Broccoli
Tilapia Walleye
0.001000.002000.003000.004000.005000.006000.007000.008000.00
Tota
l Yie
ld (g
)
Romaine lettuce
0.001000.002000.003000.004000.005000.006000.007000.00
Tota
l yie
ld (g
)
Pac Choi
Average Plant Biomass
0
5
10
15
20
25
Aver
age
plan
t bio
mas
s (g)
Kale TilapiaWalleye
05
101520253035404550
Aver
age
plan
t bio
mas
s (g)
Broccoli
-20
0
20
40
60
80
100
120
140
Aver
age
plan
t bio
mas
s (g)
Romaine lettuce
-10
0
10
20
30
40
50
60
70
80
90
Aver
age
plan
t bio
mas
s (g)
Pac Choi
Root:Shoot Ratio
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
8/1/2015 9/1/2015 10/1/2015 11/1/2015 12/1/2015 1/1/2016 2/1/2016
Root
:Sho
ot R
atio
Kale
Tilapia Walleye
0
0.05
0.1
0.15
0.2
0.25
8/1/2015 9/1/2015 10/1/2015 11/1/2015 12/1/2015 1/1/2016 2/1/2016
Root
:Sho
ot R
atio
Broccoli
Tilapia Walleye
0
0.05
0.1
0.15
0.2
0.25
8/1/2015 9/1/2015 10/1/2015 11/1/2015 12/1/2015 1/1/2016 2/1/2016
Root
:Sho
ot R
atio
Romaine lettuce
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
8/1/2015 9/1/2015 10/1/2015 11/1/2015 12/1/2015 1/1/2016 2/1/2016
Root
:Sho
ot R
atio
Pac Choi
Plant Harvest
• Plant yield did not significantly differ between tilapia and walleye systems • Nor did it differ for plant biomass and root:shoot ratio
Nutrient Differences No differences • Micronutrients
– Iron – Molybdenum – Copper – Nickel
• Macronutrients – Calcium – Sulfur – Magnesium
Water quality • Alkalinity
– Similar: 188 – 184 mg/L • Hardness
– Similar: 260 – 244 mg/L • pH
– Similar: 7.6 – 7.8 • Temperature
– Similar: 23 – 21oC (73 – 70oF)
0
10
20
30
40
50
60
Phos
phor
us (m
g/L
PO4-3
P
Phosphorus (T) Phosphorus (W)
0
20
40
60
80
100
120
140
160
Pota
ssiu
m (m
g/L
K+
Potassium (T) Potassium (W)
Nutrient Differences
00.10.20.30.40.50.60.70.8
NH 3
-N (m
g/L)
Ammonia (T) Ammonia (W)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
NO
2-N
(mg/
L)
Nitrite (T) Nitrite (W)
0
5
10
15
20
25
30
NO
3-N
(mg/
L)
Nitrate (T) Nitrate (W)
Summary • Differences in nutrients in tilapia and walleye aquaponic systems related
to composition of feed and fish absorption efficiency. – Levels within acceptable limits for both.
• Plant production did not differ between systems. • Tilapia production to market-size accomplished in 10-12 months. • Walleye production to market-size accomplished in >1 year 10 months.
Hybrid Walleye
Harvest in 307 days (10 months)
Harvest in 462 days (1 year 3 months)
Harvest in 392 days (1 year 1 month)
Aquaponics as a Commercial Industry Status - • Small but rapidly growing industry –
experiencing exponential growth. • Driven by:
• Food security & Food quality • Locavore movement • Limited fresh water and land
Industry Needs - • Aquaponic education
• Enthusiasm > Knowledge
• Employment opportunities
• Currently have:
• Large commercial ventures
• Students pursuing careers in aquaponics
• Research in crop diversity, system efficiency & economics
Aquaponics survey respondents by zip code (Love et al. 2014. PLoS ONE 9(7).)
Education/Outreach
Summary / Contacts
• UW-Stevens Point Aquaponics Innovation Center – Professional aquaponics certificate – Three college courses (semester long) – Internship opportunities – Collaborative research – http://www.uwsp.edu/aquaponics