|Green, Bartholomew - Bart|
|ENGLE, CAROLE - University Of Arkansas At Pine Bluff|
|LOCHMANN, REBECCA - University Of Arkansas At Pine Bluff|
|PHILLIPS, HAROLD - University Of Arkansas At Pine Bluff|
Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2015
Publication Date: 3/16/2016
Citation: Green, B.W., Engle, C., Lochmann, R., Phillips, H. 2016. Low-intensity, stocker-based channel catfish culture. North American Journal of Aquaculture. 78:125-135.
Interpretive Summary: Catfish farmers use a variety of pond management strategies to produce food-size catfish. One of three management strategies that has the lowest cost per pound of fish produced is a low-intensity, low-technology Channel Catfish production strategy. The low-intensity strategy is characterized by low stocking rates, a low amount of installed aeration, and no automated dissolved oxygen monitoring. Catfish processors continue to seek larger fish for processing and the preferred size range generally is stated as ranging from 1.25 to 4.00 lb, but processors likely prefer a tighter size range (1.5-2.5 lb) with minimal numbers of fish larger than 3 lb. Given the dearth of systematic research data on production of larger Channel Catfish, we conducted two studies in consecutive years whose objectives were to quantify production characteristics, including temporal changes in population size distribution and response to stocking rate, when 0.5-lb stocker Channel Catfish were stocked for food fish production at low-intensity culture either in single- or multiple-batch culture. Stocker catfish are large fingerlings that weigh from 0.2-0.75 lb, whereas fingerlings generally weigh less than 0.1 lb. In single-batch culture, ponds are stocked in the spring with a single age-class of fish and are harvested completely in the fall. In multiple-batch culture, a single age-class is stocked the fish year and only market size fish are harvested in the fall, after which fingerlings are stocked to replace the fish harvested for market. The partial harvest-restock cycle is repeated over several years. Results of the multiple-batch experiment showed that the presence of fingerlings does not impede the growth performance of the stocker Channel Catfish and that both fingerlings and stockers grew rapidly. The size class distribution of the stocker catfish shifted to higher than expected numbers of larger fish as the grow-out season progressed. Results of the single-batch experiment showed that Channel Catfish growth and yield increased linearly as stocking rate increased. Although individual fish weight decreased linearly with increased stocking rate, yield continued to increase with stocking rate because of the greater numbers of fish. The size class distribution of the stocker catfish shifted to higher than expected numbers of larger fish at the lowest stocking rate and higher than expected number of smaller market size fish at the two higher stocking rates. Ponds stocked in the spring with 0.5-lb stockers, contained by early to mid-July biomasses of market-size fish suitable for partial harvest for processing and at least 22% of the carryover fish exceeded the lower processing plant size limit. If fish larger than 1.5 lb are desired, the data indicate partial harvest should be delayed until August. None of the fish harvested exceeded the processors’ preferred size range (1.25-4.00 lb). In summary, these studies indicate that larger Channel Catfish can be produced successfully using low-intensity single or multiple-batch culture.
Technical Abstract: Low-intensity Channel Catfish production is characterized by low stocking rates, low installed aeration capacity, and no automated dissolved oxygen monitoring. Two studies conducted in nine 0.25-acre ponds quantified production characteristics of stocker Channel Catfish stocked for low-intensity food fish production in single- or multiple-batch culture. In the multiple-batch study, 0.5-lb stockers (carryover fish) were stocked at 4,500/acre and 0.044-lb fingerlings at 6,000/acre. Stockers were grown to mean individual weights of 1.25, 1.75, or 2.25 lb/fish. In the single-batch study, 0.5-lb stockers were stocked at 3,500, 4,500, and 5,500 fish/acre. All fish were fed a 32% protein feed daily to apparent satiation. Ponds were harvested in October and fish weighed. Growth of carryover fish and understock in multiple-batch culture was linear and growth curve slopes did not differ significantly. Carryover fish size class distributions differed significantly among target weights and progressively shifted towards larger size classes as target weight increased. Stocking rate affected Channel Catfish growth and yield significantly in single-batch culture. Fish stocked at 3,500 fish/acre grew faster than fish at the higher stocking rates. Mean final weight decreased linearly and gross and net yields increased linearly with increased stocking rate. Size class distributions differed significantly among stocking rates and the 3,500 fish/acre size class distribution was shifted towards larger fish compared to the other two stocking rates. Ponds stocked in the spring with 0.5-lb stockers contained by early to mid-July biomasses of market-size fish suitable for partial harvest and at least 22% of the carryover fish exceeded the lower processing plant size limit. If fish larger than 1.5 lb are desired, the data indicated partial harvest should be delayed until August. None of the fish harvested exceeded the processors’ preferred size range (1.25-4.00 lb/fish). In summary, larger Channel Catfish can be produced successfully using low-intensity single or multiple-batch culture.