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Catfish Yield Verification Trials - Final Report

by the Fish Site Editor
01 March 2004, at 12:00am

By Mr. David L. Heikes, Dr. Carole R. Engle, and Dr. Pierre Justin Kouka, University of Arkansas at Pine Bluff - In May of 1993, a pilot catfish verification program was initiated by the Arkansas Cooperative Extension System to provide production support to the catfish industry. Extension Fisheries Specialists and aquaculture researchers of the UAPB Aquaculture/Fisheries Center and district administrators of the Arkansas Cooperative Extension Service designed the original program.

Catfish Yield Verification Trials - Final Report - By Mr. David L. Heikes, Dr. Carole R. Engle, and Dr. Pierre Justin Kouka, University of Arkansas at Pine Bluff - In May of 1993, a pilot catfish verification program was initiated by the Arkansas Cooperative Extension System to provide production support to the catfish industry. Extension Fisheries Specialists and aquaculture researchers of the UAPB Aquaculture/Fisheries Center and district administrators of the Arkansas Cooperative Extension Service designed the original program.

The University of Arkansas Cooperative Extension Service and Agricultural Experiment Station have been conducting research verification trials for major row crops since 1980. The yield verification programs are interdisciplinary management programs in which all recommended production technology is applied in a timely manner on a commercial scale.

The key components of the management protocol were: 1) moderate stocking rate of 6,000 to 6,500 head/acre (50-60 lb/1000 each) annually. 2) minimum requirement of 1hp/acre paddle-wheel aeration. 3) feeding twice/day at water temperatures between 22-32C. 4) multiple batch production scenario, harvesting when a minimum of 1,000 lb/acre reach 1.5 lb on the average, and 5) accurate record keeping. Initial funding was provided by the Catfish Farmers of Arkansas and the 1890 Cooperative Extension Program.

Acknowledgments

A special thanks is extended to the Catfish Farmers of Arkansas for financially supporting this project. The authors would also like to acknowledge Dr. Craig Tucker and Dr. Ed Robinson for their contributions to the original recommendations for the verification.

Executive Summary

Production data were verified from four ponds over a three-year period with an average annual marketable yield of 4,971 lbs per acre. The estimated 1996 Arkansas state average is 2,508 lb/acre (Agricultural Statistics Board, USDA). The average pond size in the verification trials was 15 acres and the average annual stocking rate was 6,702 head per acre with fingerlings averaging 130 lbs/1000. The overall survival of the verification ponds was 65% with an average net feed conversion ratio of 2.02.

Objectives

Specific program objectives were as follows:

  • To conduct on-farm pond trials to verify the utility of research-based Extension recommendations with the intent of optimizing potential for profits.

  • To develop an on-farm database for the purpose of estimating the cost of production, feed conversion ratios, yield, and survival on commercial catfish ponds.

  • To help identify areas of production that require further research.

  • To improve or refine existing Extension recommendations which contribute to the profitable production of farm-raised channel catfish.

  • To increase county Extension agents' expertise in catfish production.

  • To utilize and incorporate data and findings from the CYVT program into Extension's educational program at the county and state level.

  • To develop and continue to refine specific management protocol for future trials.

Management Protocol for On-Farm Trials

CYVT Administration and Structure
Each year, the Catfish Yield Verification Technical Committee met to discuss and agree on recommended technology to be incorporated into the verification program. This committee was broad based and included research and Extension personnel with expertise in all subject matter relating to the production of catfish. The committee members also served as advisors throughout the three year production period. The CYVT coordinator was responsible for overseeing the implementation of the committee's recommendations.

Cooperators were chosen by the county Extension staff and the CYVT coordinator. The cooperators agreed to manage 2 ponds each according to recommendations from the Catfish Yield Verification Committee for a period of three years. The local county Extension agent visited the ponds weekly during the production season and verified all stocking, harvesting, and production inputs. The CYVT coordinator met with the county agent at the verification site on a weekly or bi-weekly basis as needed and made recommendations for action the following week. The following describes the management of the specific cooperator ponds in the program.

Cooperator Pond Management
Pond size varied from 10.6 to 20 acres (Table 1). Ponds A&B were on the same farm and were stocked initially in May of 1993. The verification period extended through September of 1995, resulting in a production period of approximately 2.33 years. This production period encompassed the majority of three full growing seasons, and two winters.

These ponds had been in production for several years prior to being drained at the beginning of the trials. Ponds C and D were on the second cooperating farm and were brand new when the ponds were initially stocked in September 1993. The verification period for ponds C and D extended through September and December of 1996, resulting in production periods of 3 and 3.25 years respectively. The production periods for ponds C and D encompassed three full growing seasons as well as three full winters.

Table 1: Catfish yield verification pond size, initial stocking dates and final pond scrapping dates.
Pond Size/Dates A B C D Average
Acres 20 16.7 10.6 11.3 15
Starting Date (Month/Year) 5/93 5/93 9/93 9/93 n/a
Ending Date (month/year) 9/95 9/95 9/96 12/96 n/a
Production Period (years) 2.33 2.33 3 3,25 2.75

Ponds A and B were stocked at an overall average rate of 5,970 and 6,295 head/acre/year with fingerlings averaging 0.065 lb and 0.073 lb respectively. (Table 2 ). Ponds C and D were stocked at a slightly higher rate to compensate for disease losses (Proliferative Gill Disease and Columnaris) that occurred shortly after the first stocking.

The resulting standing crop (head/acre) was thought to be similar to ponds A and B at initial stocking. Another significant difference in stocking strategy was the larger average weight of fish stocked into ponds C and D, averaging 0.141 lb and 0.226 lb respectively (Table 2). The overall stocking rate for all ponds in the trial was 6,702 lb/acre/year with an average weight of 0.130 lb.

Table 2: Summary of stocking data indicating the pounds and head stocked into each of the catfish yield verification ponds expressed as a three-year average, 1996.
Stocked A B C D Average
Total Fish Weight (lb/acre/year) 387 458 1,110 1,510 866
Numbers of Fish (head/acre/year) 5,970 6,295 7,860 6,685 6,702
Average Weight (lb) 0.065 0.073 0.141 0.226 0.130

All ponds were fed 32% protein floating catfish pellets. The feeding recommendation called for feeding twice a day when water temperatures were between 22 and 30C (70-86F). However, ponds A and B were fed once daily because feeding twice a day did not fit into the farm's overall management plan.

Ponds C and D were located on a farm that was set up to feed twice a day throughout the summer months, whenever possible. Pounds of feed fed on a per acre per year basis were summarized in Table 3. Ponds C and D received almost twice as much feed on per acre per year basis. This was due to a more aggressive feeding and stocking strategy and also due to the fact that smaller fish were stocked and harvested in ponds A and B.

Table 3: Feed fed (lb) and aeration usage for the catfish yield verification trials, 1996.
Feed/Aeration
Pond A B C D Average
Feed (lb/acre/year) 6,926 6,508 11,180 13,967 9,645
Electric Paddlewheel Aeration (hours/acre/year) 21 26 115 119 70
Emergency Tractor Aeration (hours/acre/year) 1 0.2 17.8 9.2 7

Dissolved oxygen levels were monitored throughout the spring, summer, and fall months. Oxygen levels were recorded from early evening through the early morning hours and electric aeration was turned on when oxygen levels dropped below 4 PPM. Emergency tractor paddle-wheel aerators were turned on when oxygen levels dropped below 2 PPM or whenever fish were piping at the surface. Each pond was equipped with paddle-wheel aeration at a rate of at least 1 hp per surface acre. Electric paddlewheel and emergency tractor paddlewheel aeration, expressed in terms of hours per acre per year, are presented in Table 3. As a result of the higher feed inputs, aeration requirements were higher in ponds C and D. Hours of tractor aeration indicate how often fish were subjected to low oxygen stress.

Water quality was monitored on a weekly basis throughout the summer months to ensure that levels of total ammonia nitrogen, toxic un-ionized ammonia, nitrite, and chlorides were at acceptable levels. Chloride levels were maintained above 60 PPM through the addition of salt when needed.

Ponds were monitored visually for disease outbreaks and any disease problems were diagnosed by H. Steven Killian at the UAPB Extension Fish Diagnostic Laboratory in Lake Village AR. Fish were treated according to Extension recommendations. Ponds B, C and D were all treated with medicated feed (Romet) on at least one occasion for acute outbreaks of ESC (enteric septicemia of catfish). Hamburger gill (proliferative gill disease) and columnaris caused significant losses in pond C in the first year of production. Catfish anemia killed a significant number of large fish in pond D just prior to the final harvest.

Fish Production, Survival, and Feed Conversion

Harvest
Harvesting commenced when records indicated that an adequate number of fish were ready to meet the demands of the existing market outlets for the particular farm. The producer was responsible for submitting samples to the plants and for making every reasonable effort to get the fish on the schedule at the processing plant. Producers agreed at the initiation of the CYVT that if fish were deemed "off-flavor" at time of harvest, the fish would be moved to another pond or purging facility.

These fish were counted as harvested for CYVT purposes of verifying commercial yield potential when research-based Extension recommendations are implemented. Given that off-flavor is a marketing problem, it's cost is a marketing, not a production cost. The variability and uncertainty in off-flavor occurrence could likely obscure production results if not separated from production effects. Harvest data collected over the duration of the trials were totaled and divided by 3 years to determine "annual" results for all ponds. Inventory remaining at the end of the three year production period was verified by draining and scrapping-out each pond in order to calculate survival, feed conversion, and yields.

Total pounds harvested as reported in Table 4 include the pounds of live fish that were recovered through the three-year production period including the pounds "scrapped" (total cleanout by seining and draining the pond) at the end of the study. The three-year average for pounds harvested in the verification ponds had a range of 4,398 to 6,687 lb/acre/year, with a mean of 5,542 lb/acre/year.

The three year average for head harvested in the verification ponds had a range of 3,673 to 4,988 head/acre/year, with a mean of 4,282 head/acre/year. The average weight of fish harvested in the verification ponds had a range of 0.98 to 1.82 lb, with a mean of 1.33 lb.

Table 4: Summary of harvested catfish weight, and population number (including ending inventory), expressed as a three-year average, and overall survival from each of the catfish yield verification ponds, 1996.
Catfish Ponds
Harvested A B C D Average
lb/acre/year 4,782 4,398 6,301 6,687 5,542
head/acre/year 4,988 4,173 4,292 3,673 4,282
Average Weight (lb) 0.98 1.05 1.47 1.82 1.33
Survival 84% 66% 55% 55% 65%

The apparent differences in average weight harvested between Ponds A & B and Ponds C & D is likely due to differences in the timing of stocking fingerlings with respect to harvest. The majority of the 6 inch fingerlings stocked in ponds A and B in May of 1995, had only reached 0.5 lb by the end of the trials in September of 1995. This contributed to the relatively low overall average weight of fish produced in these ponds of 0.98 and 1.05 lb respectively. Ponds C and D were last stocked in September of 1995 and all fish were of marketable size by September of 1996 when the trials in these ponds were terminated. This resulted in the relatively higher overall average weights of 1.47 and 1.82 in Ponds C and D (Table 4).

Overall survival was 84% and 66% in ponds A and B, respectively (Table 4). Low oxygen levels in the hauling tank delivering the fingerlings to pond B in May of 1994 may have caused higher mortality in that pond. Although very few mortalities were confirmed at the time of stocking, the pond did not perform as well as did pond A which was stocked with fingerlings from a different truck.

Survival was 55% in both ponds C and D. Hamburger Gill (proliferative gill disease) and columnaris were diagnosed as causes of mortality in Pond C early in the program. Pond D had a chronic, low level infection of ESC throughout the majority of the study and was followed by a case of anemia which killed a number of 2-3 lb fish just prior to the last major harvest. The fact that the last batch of fish stocked into ponds A and B were not held over the winter and were not large enough for "market" at the end of the study is at least in part responsible for the relatively higher survival rates reported for those ponds in table .

Yield

Yield in the verification ponds is presented in Table 5. The annual marketed yield reported in Table 5 is farm yield as measured on farms and is the annual pounds sold per acre over the three years of production. Annual marketed yield in the verification ponds ranged from 3,673 lb/acre/year in Pond B to 6,422 lb/acre/year in Pond D. The average annual marketed yield was 4,971 lb/acre/year. The overall average weight of fish marketed ranged from 1.38 in pond A to 1.83 in Pond D with an overall average marketed weight of 1.52.

Table 5: Annual Marketed Yield, Overall Net Yield, Average Weight of Fish Sold, and Feed Conversion Ratio (FCR) in catfish yield verification trials, 1996.
Yield/Average Fish Weight A B C D Average
Annual Marketed Yield (lb/acre/year) 4,055 3,673 5,732 6,422 4,971
Overall Net Yield (lb/acre/year) 4,395 3,939 5,191 5,177 4,676
Average Weight of Fish Sold (lb) 1.38 1.44 1.44 1.83 1.52
FCR Gross (a) 1.45 1.48 1.77 2.09 1.70
Net (b) 1.58 1.65 2.15 2.70 2.02
a - Gross Feed Conversion Ratio = (lb feed fed lb fish marketed).
b - Net Feed Conversion Ratio = (lb feed fed lb overall net yield).

Overall net yield is an indicator of biological production of fish in each pond. This value was obtained by subtracting the pounds of fish stocked from the total pounds of live fish accounted for through the end of the study (including the scrap). Thus, overall net yield measures the increase in fish weight regardless of the actual weight of fish sold. Overall net yield ranged from 3,939 lb/acre/year in Pond B to 6,422 lb/acre/year in Pond D (Table 5). The average overall net yield for the verification trials was 4,676 lb/acre/year.

The standard method for calculating the biological feed conversion ratio for a production study requires an ending inventory weight and is calculated by dividing the total pounds of feed fed by the total net increase in fish weight. However, in multiple batch production scenarios, commercial catfish ponds may be in production continuously for years. Thus, it is common practice for farmers to calculate an estimated feed conversion by dividing feed fed by pounds marketed regardless of pounds stocked or pounds of remaining inventory. For the purpose of this report, the standard biological feed conversion ratio is reported in Table 5 as Net FCR, and the FCR as calculated on farms is referred to as Gross FCR. Actual net feed conversion ranged from 1.58 in Pond A to 2.70 in Pond D, with a mean of 2.02. Gross feed conversion ranged from 1.45 in Pond A to 2.09 in Pond D, with a mean of 1.70. The difference between the net and gross feed conversion values was more pronounced in Ponds C and D where larger fish were stocked (Table 5).

Economic Analysis

One of the objectives of yield verification is to verify and demonstrate that recommended Extension practices will improve net farm income. During this initial pilot project, the framework was established to collect information on production costs for economic analysis.

Direct Expenses
Direct expenses are those that require cash outlays during the year. Given that the fundamental management issues of the management protocol developed for this pilot program included changes in stocking density, feeding practices, and aeration rates, detailed records were maintained of the quantities used of fingerlings, feed (32% protein and medicated) and aeration (both electric floating paddlewheel aerators and tractor-powered PTO driven emergency paddlewheel aerators). The prices used for these inputs were determined based on prices reported in southeast Arkansas as of December, 1996.

Harvesting and hauling expenses were determined by the cost in southeast Arkansas charged by custom harvesters. Other expenses, including repairs and maintenance, fuel, chemicals, telephone, water quality, labor, accounting, and bird scaring expenses were prorated on a per-acre basis from Engle and Kouka (1996). Since both farms had salaried managers, management costs were included under fixed expenses. Interest on operating capital was charged for 9 months of the year at a rate of 11%.

Direct expenses for the CYVT ponds ranged from $2,159 to $4,404 per acre, Table 8. The breakeven price needed to cover the direct expenses ranged from $0.53/lb to $0.69/lb.

Fixed Expenses
Fixed expenses represent the cost of owning and using the ponds and equipment. These costs vary greatly among farms as farm size, management skill, and use vary. Data were not collected on CYVT farms on fixed expenses in this pilot program. However, estimates of fixed expenses are necessary to report net returns per acre. In order to present complete cost and returns estimates for the CYVT, fixed expenses were taken from Engle and Kouka (1996) and included at $402/acre in Table 8. It is recommended that, in future CYVT trials, data on fixed expenses are collected. Management expenses were included under fixed expenses.

Total Expenses
Total expenses ranged from $2,561 to $4,806 per acre. Breakeven prices to cover total expenses ranged from $0.63 to $0.75/lb. Land expenses were not included in these costs. There is variation in land tenure circumstances across farms. In order to account for land use, a rent fee is charged. Breakeven prices to cover total expenses and rent ranged from $0.66 to $0.76/lb.

Net Returns per Acre
Breakeven prices when compared to market prices provide information on profit margins per pound of product sold. However, the lowest breakeven price is not necessarily the point of maximum profit. Yields also affect per-acre net returns.

Income in Table 6 was based on a market price of $0.75/lb of catfish. This price is representative of prices over the period of the CYVT pilot program. At this price, net returns per acre ranged from $11 to $472 per acre.

Yields of catfish across the industry average approximately 3,000 lb/acre/year (USDA 1996). The production costs estimated for the verification ponds based on obtained yields in those ponds were substantially lower than the costs at yields of 3,000 lb/acre/year (Engle and Kouka, 1996).

However, market price of catfish and feed prices vary and can have a large effect on net returns. To account for these effects on the costs reported in this report, three sensitivity analyses were conducted. Table 7 presents a sensitivity analysis of net returns per acre for catfish prices ranging from $0.65/lb to $0.85/lb. The sensitivity analysis of the effect of the price of feed on net returns/acre is presented in Table 8, and table 9 presents combined effects of varying feed prices and catfish prices on net returns/acre.

Additional Information

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Source: University of Arkansas Pine Bluff - May 1993-December 1996

the Fish Site Editor