Post on 03-Jan-2016
Stock Management Stock Management IssuesIssues
Michael B. Timmons Ph.D.J.Thomas Clark Professor of
Entrepreneurship & Personal Enterprise
Cornell University
Recirculating Aquaculture Systems Short Course
Production StrategiesProduction Strategies
• Continuous production strategies • can double total system production
• compared to batch strategies
• rely on year round stocking and harvesting• maintains the system near its carrying capacity
• ideal situation• not always attainable
Recirculating Aquaculture Systems Short Course
Stock Management IssuesStock Management Issues• Batch strategy
• P/B = 1.74/yr,
• ts = th = 224 days N0 = 1965
0200400600800
1,0001,200
0 56 112 168 224 280 336 392 448
Bio
mas
s, k
g
Time, days
Recirculating Aquaculture Systems Short Course
Stock Management IssuesStock Management Issues• Concurrent batch stocking and harvesting
• P/B = 3.14/yr• ts = th = 56 days N0 = 1125
0200400600800
1,0001,200
0 56 112 168 224 280 336 392 448
Bio
mas
s, k
g
Time, days
Recirculating Aquaculture Systems Short Course
Stock Management IssuesStock Management Issues• Concurrent mixed-stocking and graded harvesting
• P/B = 3.48/yr
• ts = 56 days th = 14 days N0 = 1438
.
Time, days
0200400600800
1,0001,200
0 56 112 168 224 280 336 392 448
Bio
mas
s, k
g
Recirculating Aquaculture Systems Short Course
Stock Management IssuesStock Management Issues
• For > 5 years, Freshwater Institute produced rainbow trout:• 4.6 MTON annual production• 1.0 MTON maximum biomass
• stocked every 8 weeks at 30 to 40 g• harvested weekly at 340 g • 1 mm/day growth
• vs. 2:1 to 4:1 annually for many commercial farms
Recirculating Aquaculture Systems Short Course
Stock Management IssuesStock Management Issues
• Harvesting and grading:• IMPORTANT!• can add considerably to labor cost!• mechanism/strategy must be incorporated with
culture tank design.
• Automated fish grading/pumping equipment:• reduces labor costs• can reduce fish stress and damage
Recirculating Aquaculture Systems Short Course
Harvesting and GradingHarvesting and Grading
Small box graders work well at small scale.
Recirculating Aquaculture Systems Short Course
Harvesting and GradingHarvesting and Grading
Clam-shell graders reduce labor and are easy on fish!
Recirculating Aquaculture Systems Short Course
Harvesting and GradingHarvesting and Grading
Clam-shell graders reduce labor and are easy on fish!
Recirculating Aquaculture Systems Short Course
Harvesting and GradingHarvesting and Grading
Belt graders and roller graders handle large numbers.
Recirculating Aquaculture Systems Short Course
Harvesting and GradingHarvesting and Grading
Counting channels track fish numbers after grading.
Recirculating Aquaculture Systems Short Course
Harvesting and GradingHarvesting and Grading
• Moving fish is hard work!• Fish moving equipment:
• fork lift a palletized tank• fish pumps
• heli-arc• vacuum• pescalator
• swim fish through channels and raceways
Recirculating Aquaculture Systems Short Course
Tank Access & Tank EnclosuresTank Access & Tank EnclosuresWas tank access designed into the tank layout?