Transcript Ranching, cages, net pens... How low can you go? Lecture 14: FAS 1012

Ranching, cages, net pens...
How low can you go?
Lecture 14: FAS 1012
As traditional aquaculture and fishing practices
have increases, so have the needs for alternatives.
Cage culture, ocean ranching and net pens have come under
intensive development recently.
Cage Culture
“is the cultivation of fish in existing
water resources such as farm ponds,
mining pits or barrow pits using
small
to large cages or net pens”
Advantages
• One of the only ways to grow fish for sale
in large, deep ponds, or lakes.
• If ponds are owned then relatively low
start-up costs.
• Good way to learn aquaculture at a small
scale.
Disadvantages
• Water quality may be harder to manage
• Higher potential for disease outbreak
• Vandalism is easier
Site Selection
• At least one surface acre
• Average depth of 4 ft.
• No more than 10 acre watershed per
acre of water.
• No direct access by livestock
• No chronic problems with weeds.
• No silt or pesticide runoff.
Cage Considerations
• Investment
• Management Aid
– Observation
– Feeding
– Treatment
• Design – Materials
• Harvest
• Overwintering
Cage Construction
• Floatation
• Mesh
– 1/8 to 1/4 for Phase I (1-2”)
– 3/4 for Phase II (6-8”)
• Feeding Ring
Water Quality
• Temperature
– 70ºF+
• Dissolved Oxygen
– 4 ppm+
• Nitrites
– <10ppm
• pH 6.5-9.0
• Turbidity
– Around 24”
• Alkalinity
– 40 ppm+
• Ammonia
– <1ppm
Cage Placement in Pond
Cages should be placed where water
can move freely between cages and
circulate away from immediate area
of cages.
Stocking Phase
• Stock 1-3 in. fingerlings.
• Stock when water temperature is >55oF.
• Stock around 25-35 fingerlings per ft3.
Stocking Advanced Fingerlings
• In the Midwest need to stock AT LEAST a
6” fingerling with an 8 in. fingerling
preferred.
• Stock when water temperature is >55oF.
• Stock 6-8 fingerlings per ft3.
Feeds
• Juveniles
– Non floating
– Crumble size particle
– 40% CP or greater
• Advanced Fingerlings
– Floating pellets
– 36% CP acceptable
Feeding
• Juveniles
– Feed often and plenty
– Hand feeding or automatic feeders
• Advanced Fingerlings
– Morning and afternoon best
– Hand feeding...
advantageous, but slow
Management
•
•
•
•
Grading of fingerlings
Predator Control
Weed Control in Ponds
Algae Control on Cages
Diseases
• Columnaris early in the season or from handling
stress.
• Gill Flukes
• Cannibalism among some small fish an issue.
Harvesting
• If fish are stocked in April,
then should be market size
by late October (for HSB).
• Forewarned is forearmed…
Be prepared!!
Overwintering
• Success depends on condition of fish after
harvesting and possible winter kills.
• Blowers will keep ice from around the cages.
Economics
• Break-even price for 5,000 lb production
was $1.27/lb for HSB.
• Based on:
–
–
–
–
five acre pond
6 month production cycle – 10% death loss
$75/100 six inch fingerlings – $25/cwt feed
1,000 lbs per acre yield
– 2.0 FCR