1 Pond Fertilization to Enhance Fish Growth Chris Hartleb University of Wisconsin – Stevens Point Pond Fertilization Most important factor limiting efficiency in pond culture is lack of knowledge on feeding dynamics. Fertilization can aid in first feeding by fish. Fertilization can provide supplemental feeding. Fertilization in Larviculture Least understood stage. “Green water” phase. Influenced by: Type & abundance of food. Timing & weather. Nutrients Phytoplankton Zooplankton Perch
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Pond Fertilization to Enhance Fish Growth
Chris Hartleb
University of Wisconsin – Stevens Point
Pond Fertilization
Most important factor limiting efficiency in pond culture is lack of knowledge on feeding
dynamics.
Fertilization can aid in first feeding by fish.
Fertilization can provide supplemental feeding.
Fertilization in Larviculture
Least understood stage.
“Green water” phase.
Influenced by:
Type & abundance of food.
Timing & weather.
Nutrients
Phytoplankton
Zooplankton
Perch
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Inorganic Fertilization
Primary components: Nitrogen (N), Phosphorus (P), and Carbon (C).
Often used: Powdered urea (N), triple-super-phosphate (P2O5) or phosphoric acid, and agricultural lime (CaCO3).
Enhance autotrophic food webs.
(small, green algae)
Inorganic Fertilizer
Frequent application to sustain food chain.
Can be costly depending on frequency of application.
Dry ingredients must be mixed into a liquid and sprayed on pond.
Phosphorus is absorbed by pond soil, while nitrogen remains in water.
Nutrient content in bag not always same as on label.
Organic Fertilization
Various types: Animal manures (poultry, bovine, etc), and Plant material (hay, alfalfa, cottonseed, soybean meal, etc).
Pond fertilization schedule showing fertilizer applied to Pond A
Date Urea-N
(lbs)
Phosphoric acid
(oz)
PO4-P
(ug/L)
NH3-N
(ug/L)
NO3-N
(ug/L)
N:P
4/23 25 15
5/1 25 15
5/7 25 14
5/9 4 30 0 12:1
5/14 30 14
5/16 7 20 333 50:1
5/20 15 6
5/23 7 40 533 82:1
5/28 0 11
5/30 4 120 133 63:1
6/6 7 280 133 59:1
6/13 13 50 200 19:1
6/20 21 0 233 11:1
6/27 19 40 433 25:1
7/3 11 40 300 31:1
Pond fertilization schedule showing fertilizer applied to Pond B
Date Urea-N
(lbs)
Phosphoric acid
(oz)
PO4-P
(ug/L)
NH3-N
(ug/L)
NO3-N
(ug/L)
N:P
4/23 25 15
5/1 25 15
5/7 35 14
5/9 6 0 233 39:1
5/14 35 14
5/16 13 20 366 30:1
5/20 12 10
5/23 10 30 1300 133:1
5/28 0 11
5/30 20 170 100 14:1
6/6 20 80 100 9:1
6/13 27 20 166 7:1
6/20 14 10 166 13:1
6/27 21 20 366 18:1
7/3 21 0 333 16:1
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Growth (TL) of Larval Perch from Ponds A & B
Date
5/6/02 5/20/02
6/3/02 6/17/02
7/1/02 7/15/02
Length
(m
m)
0
10
20
30
40
50
60
y = 5.4097e0.2124x
r2 =0.96
Date
5/6/02 5/20/02 6/3/02 6/17/02 7/1/02
Length
(m
m)
0
5
10
15
20
25
30
35
40
r2 = 0.95
y= 4.4376e0.2061x
Pond A
Pond B
Growth (wet weight) of Larval Perch from Ponds A & B
Date
5/6/02 5/20/02 6/3/02 6/17/02 7/1/02
Weig
ht (
g)
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
r2 = 0.95
y = 0.0003e 0.7453x
Date
5/6/02 5/20/02
6/3/02 6/17/02
7/1/02 7/15/02
Weig
ht (g
)
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
y = 0.0009e 0.7474x
r2 = 0.97
Pond A
Pond B
Conclusions
Application of fertilizer based on transparency to establish “green water” not a good indicator of pond fertilization or trophic cascade.
Diet shift by larval perch evident after 4 weeks in culture ponds.
Early growth was strongly temperature dependent. Poor survival related to low density of preferred prey. Late season variability in growth related to diet and feed