Production Parameters and Breakeven Costs for Yellow Perch Grow-out in Recirculation Aquaculture Systems

Transcription

1 Production Parameters and Breakeven Costs for Yellow Perch Grow-out in Recirculation Aquaculture Systems Authors: Jim Held, Greg Fischer, Jeff Malison, Chris Hartleb, Sarah Kaatz, Kendall Holmes Introduction For over 30 years the yellow perch has been viewed as a species with great potential for aquaculture in the North Central Region (NCR). The species has been the focus of a significant amount of research over this period, and has been a priority species for research sponsored by the North Central Regional Aquaculture Center (NCRAC) since its inception in Despite these efforts, however, until recently almost no information has been available on real world production parameters and costs of raising yellow perch to market size using different system types. The lack of such basic information is the most important reason for the failure of more than 30 yellow perch farms that were based primarily on recirculation aquaculture systems (RAS). In the mid-1990 s, two scientists (Jean Rosscup Riepe, then at Purdue University, and Harvey Hoven, then at University of Wisconsin-Superior) developed enterprise budgets for raising yellow perch in ponds, net pens and RAS (Riepe, 1997a,b; Hoven 1998). These models, although useful, had significant limitations because they used theoretical or best guess estimates for many production parameters including growth rates, food conversions, rearing densities, and survivals. Clearly, these parameters have an overarching effect on production costs. Recognizing the limitations of the budgets developed by Riepe and Hoven, NCRAC funded a major research effort from 2001 to 2004, the primary goal of which was to gather information on real world production parameters and costs of raising yellow perch to market size using different system types. This publication is a summary of the information collected on recirculation aquaculture systems. Production Parameters In 2006 through 2007 we conducted yellow perch grow-out trials in a recirculation aquaculture system located at the Northern Aquaculture Demonstration Facility (NADF) in Red Cliff, WI. The trials were undertaken to document production parameters of yellow perch reared under RAS conditions. These parameters include: growth rate, feed conversion, survival and rearing density. The study also documented important water quality parameters (Table 1.) critical to the successful culture of yellow perch in a RAS. The parameters developed in these trials are used in the accompanying economic model to provide real world values that generate break-even costs for the grow-out production of yellow perch in RAS culture. System components Yellow perch for this study were cultured in two 10,757 L (2842 gal) round, fiberglass tanks which were part of a fully recirculating 41,635 L (11,000 gal) system (Figure 1) do we want to include the system schematic? supplied by Marine Biotech Inc. (MA). Tanks were fitted with side drain and bottom drain configurations as described in Timmons et

2 al. (2002). Mechanical filtration was provided by a microscreen drum filter (Hydrotech Model 801, Water Management Technologies Inc., LA) fitted with 60 micron screens. Biofiltration was provided by a 3.6m³ fluidized sand biofilter (CycloBio, Marine Biotech Inc., MA) filled with 1.4m³ silica sand. A CO 2 stripping column and blower was utilized for aeration and a pressurized oxygen cone provided gaseous oxygen to the distribution water. Oxygen was supplied to the cone by a permanent station liquid oxygen tank (Praxair Inc, MN). UV irradiation was supplied by one 920 watt, 8 bulb unit (Model MWUV, Aqualogic, CA) plumbed into the tank water distribution line. A custom fiberglass 8.0 cubic meter sump with pumping stations for two 2.0 hp bio-filter pumps and two 2.0 hp distribution pumps (Hydrotech Inc.) supplied an average 1,480 L/min (391gal/min) continuous water flow, as monitored by a pipeline mounted paddlewheel flowmeter (Model flow meter, Signet Scientific Company, CA) connected to the system. Pumping and water levels monitored with a SCADA system (LW Allen and Intellisystems Inc., WI) which includes a phone auto-dialer in case of emergencies. Tanks were partially covered with 1 foam insulation board to reduce direct lighting. Photoperiod was controlled by timers (Model T103, Intermatic Inc., Ill.) to provide hrs of daylight throughout the study period. One 3,000-watt submersible heater and controller (Aquatic Ecosystems, FL) was utilized in the sump to maintain system temperature. Ground water (7.6 C) at 4.7L/min (< 1% of total flow) was added to the RAS sump to replace system water lost to evaporation and drum filter spray-bar operation. Culture conditions Mendota Lake strain yellow perch (mixed sex and monosex females) fingerlings were obtained from two private sources on November 8, Approximately 6,000 feedtrained, pond raised, fingerlings (avg. 127mm TL, 5in) of each group were placed into two 10.8m³ (10,757 L) round, fiberglass tanks connected to the larger RAS system for further rearing. Initial stocking densities were 9.4kg/m³ and 9.3kg/m³for the mixed sex fish and monosex fish, respectively. Additional perch were stocked into other tanks to increase the total loading of the system. Automatic vibratory feeders (Model SF7, Sweeney Inc., TX) set on feeder controllers (Model H1201, Aquatic Ecosystems Inc., FL) dispensed 0.5 g feed per day/per fish of 46% protein, 16% lipid, 1% fiber, 9% ash extruded steelhead diet (Nelson Silver Cup Inc., UT) of appropriate size. Water temperature averaged 19.0ºC and ranged between C. Tanks were cleaned and monitored daily. Mortality was recorded and dead fish were removed daily. Yellow perch length and weights were measured monthly by obtaining 50 randomly sampled perch from each tank. Dissolved oxygen (mg/l), temperature (C), and total dissolved gases (%) were measured daily in each tank (Common Sensing Model TBO- DL6F Gas Meter, Common Sensing Inc., ID). ph was monitored daily in each tank (Pinpoint ph meter, American Marine Inc, CT). Ammonia-nitrogen (NH 3 -N), nitritenitrogen (NO 2 -N), and reactive phosphorous (PO 4 ) were measured (CEL 850 Hach Test Kit, Hach Inc., CO) weekly from water samples collected in the RAS sump according to standard water quality methods (APHA 1989). RAS system routine maintenance included monitoring flow rates, sand filter biofloc removal, tank cleaning, and power washing of the drum filter.

3 Table 1. Water quality parameters observed during study period in yellow perch RAS. Parameter Average Value Temperature (ºC) 19 Dissolved oxygen (mg/l) 7.8 ph 7.7 Carbon dioxide (mg/l) 30 Total ammonia nitrogen (mg/l) Nitrite nitrogen (mg/l) Calculated unionized nitrogen (mg/l) < Total suspended solids (mg/l) Alkalinity (mg/l) 135 System Performance Observed water quality parameters in the water recycle system during the study were appropriate for yellow perch (Table 1.). Measured total ammonia nitrogen (NH 3 +NH 4 ) and nitrite nitrogen (NO 2 -N) levels ranged from mg/L Calculated unionized ammonia (NH 3 -N) levels did not exceed the safe level of mg/l as recommended for most species by Meade (1989), although one increase of nitrite nitrogen (NO2-N) and total ammonia nitrogen (NH 3 +NH 4 ) above 0.1mg/L was noted at the end of the study just before harvest when the system was at its heaviest load. Measured tank temperatures averaged 19ºC and ranged from º C (Figures 3 & 4). Baseline alkalinity averaged 135mg/L, ph averaged 7.7 and ranged from Sodium bicarbonate (Church & Dwight Company, Princeton, NJ) was added weekly to maintain alkalinity in the system. Carbon dioxide concentration averaged 35mg/L and ranged from 20-63mg/L. Total suspended solids (TSS) were maintained at <5.0 mg/l by utilizing a micro screen drum filter. Measured dissolved oxygen concentration in RAS tanks averaged 7.8mg/L and ranged from mg/L (Table 1). All water quality parameters were within the acceptable range for yellow perch (Brown et al., 2008) and no adverse health effects were noted. Fish performance One of the most important considerations for modeling production in a RAS is the rate of fish growth. This parameter impacts the duration of time needed to achieve market size (cycle length) and therefore the productivity (in pounds of fish) that can be realized from a system on an annual basis. Average weight gain of the perch in our study can be seen in figure 1. The growth curve has been expanded to account for weight gain beyond the scope of this particular trial, and represents the average growth of the mixed-sex and monosex cohorts. Since the growth of perch is not a linear function, the size at which one begins the production cycle has a significant impact on the growth rate and accordingly

4 the cycle length. For example a 4-inch (11g) perch would take 199 days to reach market size (114g or 4 fish/lb) and have an average growth rate of 0.52g/d while a 5.5-inch (32g) Yellow Perch Growth /1/06 10/15/06 10/29/06 11/12/06 11/26/06 12/10/06 12/24/06 1/7/07 1/21/07 2/4/07 2/18/07 3/4/07 3/18/07 4/1/07 4/15/07 4/29/07 5/13/07 5/27/07 6/10/07 6/24/07 Weight (g) Fig.1. Average growth of yellow perch in a recirculation aquaculture system at 19 C perch would take 113 days to market size and have an average growth rate of 0.72g/day. If one started with 4in perch you could complete 1.8 production cycles in a year, starting with 5.5in fish allows 3.2 production cycles. Regardless of the capacity or loading of the system, more production cycles per year results in more pounds of fish produced and therefore more gross revenue. Table 2 converts the growth results in Figure 1 to growth rate and production cycles per year for a variety of initial yellow perch sizes. Table 2. Growth rates and production for a variety of initial yellow perch sizes. Initial size (in) Average weight (g) Final weight (fish/lb) Growth rate (g/day) Production (cycles/year)

5 Fingerling quality Figure 2 is a graph of the growth data collected from the two cohorts studied in this trial. Examination of the data reveals two very different growth rates even though the fish are of similar size. The monosex cohort was in good health and prime condition, and showed a growth rate of 0.72g/day. The mixed-sex cohort was stressed by low oxygen during transport, experienced a number of mortalities within the first week after arriving at the facility, and ultimately showed an average growth rate of 0.43g/d. This serves to illustrate the importance of using good quality fingerlings for grow-out. At those growth rates, the monosex cohort would achieve market size in 123 days. The mixed sex cohort would achieve market size in 184 days even though they started out 10g larger than their counterparts. In developing the economic model we though it reasonable to average the two growth curves (fig. 1) so that the enhanced growth potential of the all-females would be offset by the poor performance of the mixed sex group. Similarly, the two cohorts studied experienced very different mortality rates. The economic model uses the average of the two groups (14%) but can be changed to suit the expectations of the individual producer. Growth of Yellow Perch in RAS Monosex Weight (g) Mixed-sex 20 0 Jan-07 Feb-07 Mar-07 Apr-07 Figure 2. Growth of mixed-sex and monosex yellow perch in a recirculation aquaculture system at 19 C. System Loading The production capacity of any system is limited by the pounds of fish per gallon that can be maintained without affecting water quality to the point that it impacts the growth or health of the fish. We calculate the loading rate based on the total system volume rather

6 than the volume of the culture tanks. Due to budgetary constraints and fish availability our study reached a maximum loading of 0.22lbs./gal. This is about two-thirds of the typically accepted safe loading, and it is not unusual (although not recommended) for culturists to operate at densities as high as 0.5lbs./gal. or higher. The accompanying spreadsheets containing the economic model are designed to accommodate changes in system loading density (as well as other variables) to better serve as an analytical tool for prospective RAS operators. Enterprise Budgets To develop enterprise budgets, we infused the model initially developed by Riepe (1997b) with the actual production costs that were recorded during our study. This publication includes three spreadsheets (one for investment costs and two for production costs) using the actual costs and production parameters obtained during our study. These spreadsheets are available for downloading at http.. By downloading these spreadsheets, individuals will be able to change most of the variables in the models to obtain breakeven costs customized for their specific information. Our assumptions relevant to the economic model are as follows: Land appreciates at 5% per year. 100% of the money for investment is borrowed at an interest rate of 6.5% per year. Interest only is paid (i.e., any repayment of the original investment debt is considered profit beyond breakeven). 100% of the money for operating costs is borrowed at an interest rate of 6.5% per year. Money is borrowed at the beginning of the production cycle and paid back in full at the end of each cycle. Under the annualized cost column, repayment is prorated for any fractional portion of a cycle. All fish within a given production run are sold at the end of the cycle. Under the annualized cost column, production is prorated for any fractional portion of a cycle. Table 3. is a listing of the investment and depreciation costs for the system at NADF. Most of the system and equipment costs are based on actual expenditures although some of the facility costs are prorated or outsourced since the NADF building and infrastructure are not solely dedicated to this one system. Recirculation aquaculture systems are almost always custom designed and vary widely in their components. We recommend that the user examine and adjust capital equipment costs to more closely reflect the actual system being modeled. However, since the economic model only considers the interest on the investment in its breakeven calculation, the impact of higher or lower capital expenses is fairly negligible. The reason for only including the interest is that payments on the principal would accumulate equity that should be considered profit and not part of the break-even calculation.

7 Table 3. Investment costs for grow-out of yellow perch in RAS. Category Item Unit Unit cost No. Total cost Useful life Depreciation Facilities (years) (annual) land cost acre $3,500 1 $3, well (5 gpm) each $5,000 1 $5, building 40 x54 each $20,000 1 $20, plumbing system $5,000 1 $5, aeration system system $500 1 $ heat system system $10,000 1 $10, electrical service system $10,000 1 $10, backup generator each $2,000 1 $2, water softener each $2,000 0 $ autodialer each $200 1 $ Subtotal $56,200 $1,710 Equipment tank assembly (11 dia) each $4,405 2 $8, tank assembly (8 dia) each $2,435 2 $4, tank assembly (4 dia) each $1,535 4 $6, drum filter each $15,000 1 $15, fiberglass sump each $8,380 1 $8, filter pump station each $3,688 1 $3, distribution pump station each $4,846 1 $4, sand bed reactor each $9,740 1 $9, stripping column each $6,805 1 $6, uv disinfection each $12,683 1 $12, ,171 oxygen cone each $3,115 1 $3, foam fractionator each $4,025 1 $4, immersion heater each $1,000 1 $1, well pump each $300 1 $ blower each $600 2 $1, d.o. meter each $300 1 $ feeder each $0 12 $0 5 0 balance each $300 1 $ nets each $25 6 $ boots/waders each $50 3 $ totes each $5 10 $ buckets each $2 10 $ tools asst $300 1 $ ph meter each $100 1 $ Hach kit kit $200 1 $ microscope each $500 1 $ lab equip/ glass asst $200 1 $ maint equip / supplies asst $200 1 $ big scale each $200 1 $ Subtotal $93,272 9,799 Total investment $149,472 Total depreciation 11,509

8 Discussion and Conclusions Tables 4 and 5 are two separate cost analyses calculating the break-even costs for yellow perch production in RAS. The difference between the two can be found in the system loading value. Table 4 uses the actual value we calculated during the production study (0.22 lbs/gal) and Table 5 employs a commonly accepted safe value (0.33 lbs/gal). In both cases the loading is based on the total system volume (including sump, bioreactor, drum screen, etc. at operational levels) and not on the culture tank volume. Breakeven costs for these two examples are $11.44 (0.22 lbs/gal) and $8.65 (0.33 lbs/gal) well above what could be a reasonably expected for perch in the round (about $3.00/lb), so the economic outlook for perch in our system would be bleak. In fact if you only considered the operating costs, i.e. the system and its ownership costs are free, the breakeven cost of $5.74 would still be almost 2 times higher than the expected market value of the fish. Similarly if you eliminate the cost of the fingerlings from the calculation, i.e. the fish are free, the breakeven cost becomes $6.55/lb (data not shown). Another money losing proposition. We examined a number of scenarios to see whether a profitable protocol could be found. Figures 3 and 4 are sensitivity analyses of several variables for the culture of yellow perch in our 19 C RAS. Figure 3 shows the total (per lb.) cost of raising perch from a variety of starting sizes (4in through 6.5in) to several market sizes (4/lb. through 3/lb.). As can be seen, the larger the starting size of the fingerling, the lower the cost. This is the result of two similar considerations; larger fish have a faster growth rate and a shorter production cycle so that more pounds of fish can be produced from a given system on an annual basis. The lower total cost of the smaller market size (4fish/lb) at a given initial fingerling size also relates to the shorter production cycle leading to more pounds of fish produced on an annual basis. The analysis does not address the potential increase in value that a larger (3/lb.) may have over a 4/lb. market size fish. It is possible that a 3/lb. perch may be $0.68/lb. more valuable (using a 5.5 inch starting size), but it is unlikely that growing perch for $8.00/lb. (approx.) would be profitable. Even the lowest cost scenario in this example, growing a 6.5in. fingerling up to 4 fish/lb., results in a total cost that is roughly twice the going rate ($5.95) for perch in the round. Figure 4 shows the operating and total costs for growing yellow perch from a 5-inch initial size up to 4 fish/lb. in our system varying the system loading density from 0.1 lb/gal up to 1 lb/gal. It is obvious that increasing the system loading density lowers the breakeven cost considerably, but even at 1 lb/gal the operation is still not profitable ($4.91/lb). Ultimately we were able to find a profitable scenario ($2.96/lb) by growing 4- inch fingerlings up to 4/lb fish but we needed to increase the system loading density to an incredible 9 lbs/gal. Most culturists would agree that this density is well beyond the capability of current recycle technology. The flexibility of the economic model provides an almost infinite number of scenarios to test. Our analysis has only scratched the surface, and we invite others to use the model in search of a favorable combination. One factor that may deserve investigation is increasing the culture temperate to 23 C. This should increase growth rates but may also have a detrimental effect on fish health and survival. Growth rates and survival would

9 need to be generated for perch at 23 C before the model could be reconfigured to reflect these changes

10 Table 4. Breakeven costs for grow-out of yellow perch in a RAS at 19 C maximum loading 0.22lbs/gal. Breakeven cost for yellow perch grow-out in an RAS at 19 C Choose one Cycles per year 2.6 Initial fingerling size inch 5 4, 4.5, 5, 5.5, 6, 6.5 Maximum loading lbs/gal 0.22 Initial fingerling cost $/inch 0.09 System capacity gal 11,000 Final fish weight fish/lb 4 3, 3.5, 4 Feed to gain ratio 1.5 Mortality rate % 14 labor/day hr 2 % of total % of operating Category Item Unit Unit cost No. of units/cycle Cycle cost Annualized cost cost cost Production costs fingerlings each $ ,035 $4,966 $12, feed lb $0.60 3,630 $2,178 $5, chemicals asst. $400 $1, oxygen liter $ ,162 $30 $ LOX system rental month $ $1,546 $4, electricity $/kwh $ ,851 $3,828 $9, labor (semi-skilled) hr $ $3,510 $9, ($ % fringe) Total production costs $16,458 $42, Sales/Marketing costs ice lb $0.07 1,210 $85 $ pickup charge mile $ $188 $ Total sales/marketing costs $272 $ Miscellaneous interest on operating capital % 6.5 $418 $1, cycle length days 140 Total operating cost $17,148 $44, Production (lbs) ,292 Breakeven operating cost per lb. $7.09 Annual ownership costs total annual depreciation $11, (investment/useful life) heat months $ $1, interest on investment $9, r.e.taxes $2,000 insurance $3,000 repairs $0 0.0 Total annual ownership cost $27, Total annual cost $72, Production (lbs) 6,292 Breakeven total cost per lb. $11.44

11 Table 5. Breakeven costs for grow-out of yellow perch in a RAS at 19 C maximum loading 0.33lbs/gal. Breakeven cost for yellow perch grow-out in an RAS at 19 C Choose one Cycles per year 2.6 Initial fingerling size inch 5 4, 4.5, 5, 5.5, 6, 6.5 Maximum loading lbs/gal 0.33 Initial fingerling cost $/inch 0.09 System capacity gal 11,000 Final fish weight fish/lb 4 3, 3.5, 4 Feed to gain ratio 1.5 Mortality rate % 14 labor/day hr 2 % of total % of operating Category Item Unit Unit cost No. of units/cycle Cycle cost Annualized cost cost cost Production costs fingerlings each $ ,553 $7,449 $19, feed lb $0.60 5,445 $3,267 $8, chemicals asst. $400 $1, oxygen liter $ ,162 $30 $ LOX system rental month $ $1,546 $4, electricity $/kwh $ ,851 $3,828 $9, labor (semi-skilled) hr $ $3,510 $9, ($ % fringe) Total production costs $20,030 $52, Sales/Marketing costs ice lb $0.07 1,815 $127 $ pickup charge mile $ $188 $ Total sales/marketing costs $315 $ Miscellaneous interest on operating capital % 6.5 $509 $1, cycle length days 140 Total operating cost $20,853 $54, Production (lbs) ,438 Breakeven operating cost per lb. $5.74 Annual ownership costs total annual depreciation $11, (investment/useful life) heat months $ $1, interest on investment $9, r.e.taxes $2,000 insurance $3,000 repairs $0 0.0 Total annual ownership cost $27, Total annual cost $81, Production (lbs) 9,438 Breakeven total cost per lb. $8.65

12 $13.00 $12.00 $ $10.98 $11.31 $ /lb total cost 3.5/lb total cost 3/lb total cost $10.00 $9.00 $8.00 $7.00 $ $ $9.11 $ $8.17 $ $7.00 $ $6.28 $6.66 $ Initial Size (in) Fig. 3. Analysis of total cost for the production of yellow perch in a 19 C RAS loaded at 0.33 lbs/gal of system capacity. Variables include initial size (in) and final weight (fish/lb). $14.00 $12.00 $12.28 $10.00 $9.21 Operating Cost Total Cost $8.00 $6.00 $4.00 $7.49 $6.01 $5.28 $7.67 $4.83 $6.75 $4.54 $6.14 $4.33 $5.70 $4.17 $5.37 $4.05 $5.11 $3.95 $4.91 $2.00 $ System Loading (lbs/gal) Fig.4. Analysis of operating cost and total cost of growing yellow perch in a 19 C RAS from 5in to 4fish/lb at a variety of system loading values.

13 Discussion and Conclusions The investment and production costs displayed in the tables in this paper represent the real expenditures at CWF and LMSFH from 2001 to Depreciation rates can vary, but we note that most of the ponds, wells and major utilities at the LMSFH are over 50 years old. Any models such as these do, however, have limitations based on location, time, and a wide range of other variables. Land and pond construction costs, for example, can vary greatly by location. Location will also affect water temperature and growing season. Likewise, feed, labor, and fingerling costs can vary greatly over time and location. Potential producers should also be aware of market limitations on the availability and quality of fingerlings. The authors strongly suggest that anyone using these models should download the available spread sheets and manipulate different variables to evaluate their effect on production costs. For example, changes in fingerling price and food conversion have major effects on production costs, whereas changes in investment costs and depreciation rates have relatively minor effects. The authors also suggest that anyone considering yellow perch aquaculture study all available literature thoroughly, especially the references cited in this paper. One striking feature of both one year and two year models is the extremely high relative costs of purchasing fingerlings (approximately76% of the total production costs for the one year scenario, and 45% of the total costs for the two year model). For the aquaculture of most other food fish species, fingerlings normally represent no more than 10-30% of the total production costs. The disparity between yellow perch and other species can be largely attributed to the fact that yellow perch are harvested at a comparatively small size.

14 It should be noted that our models use the approximate wholesale price for purchasing fingerlings in 2005 (according to personnel of CWF). Fingerling costs could possibly be lowered significantly if one were to produce their own fingerlings. Regardless of production scenario, however, the development of methods for reducing fingerling production costs will clearly have a major impact on the efficiency of yellow perch grow out. The savings on initial fingerling costs makes a two year grow out scenario more than 10% more efficient than a one year scenario. By its very nature, however, a two year scenario carries higher risk, because the fish need to be kept alive and healthy for a much longer period of time. The grow out of yellow perch in pond systems, in either a one- or two year scenario, is apparently much more efficient than grow out in recirculating systems, net pens, or flow through systems. The mean breakeven costs for the different system types have recently been reported as follows: pond, one year - $2.98/lb, pond two year - $2.63/lb, recirculating systems $6.86/lb., net pens - $4.80/lb., and flow-through - $5.50/lb (NCRAC 2006). These numbers suggest that grow out of yellow perch in ponds could be a profitable endeavor. Profitability, however, is highly dependent on both yellow perch markets and the marketing strategies of the producer. Over the past decade, the wholesale market price for yellow perch in the round has varied considerably, both seasonally and annually. It is important to note that profitability of the one- and two year production scenarios are approximately equal (approximately $58,000) at a market price of $3.30/lb. Prices lower than $3.30/lb make the two year scheme comparatively more profitable, while prices higher than $3.30/lb favor the one year production cycle. Yellow perch market factors are discussed in more detail by Malison (1999). Most producers will recognize that marketing value-added products, such as processed fillets, offer the potential of improving the bottom line. References Hart, S.D., D.L. Garling, and J.A. Malison Yellow perch (Perca flavescens) culture guide. North Central Regional Aquaculture Center Culture series???? Ames, Ia. Hoven, H Economic model for yellow perch recirculating aquaculture system. World Aquaculture Society Book of Abstracts, 29 th Annual Meeting of the World Aquaculture Society, Las Vegas, Nevada, February 15-19, Malison, J.A (updated 2003). A white paper on the status and needs of yellow perch aquaculture in the North Central Region. Special publication of the North Central Regional Aquaculture Center, East Lansing, MI, 15 pp.

15 North Central Regional Aquaculture Center (NCRAC) NCRAC annual progress report NCRAC, Michigan State University, East Lansing, MI. Riepe, J.R. 1997a. Enterprise budgets for yellow perch production in cages and ponds in the North Central Region, 1994/95. NCRAC Technical Bulletin Series #111, NCRAC Publications Office, Iowa State University, Ames. Riepe, J.R. 1997b. Costs for Pond Production of Yellow Perch in the North Central Region, NCRAC Fact Sheet Series #111, NCRAC Publications Office, Iowa State University, Ames.