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Shrimp Farming in Arizona
Josh Wilkenfeld’s Presentation at Aquaculture America 2003
At Aquaculture America 2003 (Louisville, Kentucky, USA, February 18-23, 2003), Josh Wilkenfeld, farm manager at Arizona Mariculture Associates, gave a great presentation on his farm and the three other shrimp farms in southwestern Arizona. He showed 38 slides. What follows are comments from the notes section of his Power Point presentation. I added his picture and the map.
Struggling for a Place in the Sun
Introduction: I’ll give a synopsis of the production history in Arizona and some detailed data from the farm that I run, which is Arizona Mariculture Associates. I’ll discuss some of the problems the industry has encountered, and I’ll talk a bit about the different approaches the various farms have taken in trying to make a buck in today’s difficult shrimp market.
Why the Sonora Desert: What the heck are we doing farming shrimp in the middle of the Sonora Desert? Surprisingly, there is actually an enormous amount of underground water in Arizona, especially in areas not far from the Colorado and Gila River beds. The four farms I’ll be telling you about are all very close to the Gila River, which is now completely dry as a result of dams and diversions for various irrigation projects. In our area, the water table can be found 35 to 75 feet down. At my home in Yuma, it’s only eight feet down.
A lot of this water is brackish, and therefore marginal for normal agricultural crops. The cost of land is about $1,000 per acre ($2,500 per hectare), which is way less than in coastal areas. In the areas where the farms are located, there is no strong competitive use for land, or water, and the regulatory agencies have been very aquaculture friendly. And of course a main attraction is the absence of shrimp viral diseases. All sources of incoming PLs are monitored regularly by Dr. Don Lightner at the University of Arizona Aquaculture Pathology Laboratory, and so far, there have been no reports of any viral diseases in Arizona.
A Little History: There’s been some farmed shrimp produced in Arizona for the past five years. From 1998 through 2000, most of the production (between 40-50 metric tons a year) was from the oldest farm, Desert Sweet Shrimp (formerly known as the Woods Brothers Shrimp Farm), with a smaller amount (18-30 metric tons) from what was then Super Shrimp. Significant changes occurred in 2001 and 2002. The Super Shrimp farm became the Ewing Shrimp Farm, Desert Sweet added about 9.5 hectares of ponds, and Arizona Mariculture and Arizona Shrimp Company brought more ponds into production and increased their yields.
The Four Amigos: All four farms have some fairly conventional dirt ponds ranging from 0.7 to 10.0 hectares. Three of the four farms have also tried various forms of fairly radical, relatively untested culture systems, and all three have been disappointed with the results. This year all four farms are focusing their efforts on the conventional dirt ponds, with stocking densities ranging from 6–60 per square meter, depending on availability of money, water, manpower and aeration, not necessarily in that order.
We will continue to use our ten hectares of dirt ponds and 1.7 hectares of lined ponds this year. The small lined ponds can be intensively managed to produce crops over the winter. Arizona Shrimp Company will run 40 to 80 hectares of ponds this year, but Desert Sweet will only use its 9.7 hectares of standard dirt ponds. Ewing Shrimp Farm will run 31.5 hectares of extensive dirt ponds this year. So in 2003, Arizona will have between 100 and 135 hectares in operation.
All the farms plan to incorporate reservoirs for conserving and reusing water.
At Arizona Mariculture Associates, we use our small lined ponds for commercial growout and for broodstock rearing. The dirt ponds are used for growout only. We have tried growing two crops a year in the lined ponds, but the growth rate is very slow (about 0.8 grams a week, regardless of density). So this year, I am planning for one crop of late season shrimp from the lined ponds, timed to coincide with strong demand for live shrimp at that time. We use between 40–60 HP of aeration per hectare and run incoming water through aeration towers. Stocking densities have usually been about 140 per square meter, but because survival has always been fairly low (33–40%), I plan to stock at higher densities in 2003, so we can ensure reasonable production in terms of kilograms per hectare in order to justify the electrical and manpower costs.
All but one of our existing dirt ponds slope from side to center and from inlet to drain, with an average depth of about 1.4 meters. We have one pond constructed using the ditch and dike technique (described below). We use aeration towers at the inlet of each pond.
I’ve mentioned the aeration towers a couple of times. We got this idea from Dr. Don Lightner who had seen them at Bill Engler’s Pacific Aquafarm (fish) on the Salton Sea. It’s just a simple wooden tower with five layers of screen for the water to splash through. During the summer months we leave the sides completely open so that the towers cool as well as aerate and degas. During the cooler months, we wrap the towers to cut down on evaporative cooling.
Now in its sixth year of commercial production, Desert Sweet Farms is the oldest of the shrimp farms in Arizona. Desert Sweet has tried a number of stocking densities and now works with 60 per square meter, and this year, Craig Collins, farm manager, plans to work at that density with only about 6 HP of aeration per hectare.
At the Ewing Shrimp Farm and Arizona Shrimp Company, the construction method is primarily ditch and dike: a ditch is excavated inside the perimeter of the proposed pond and the dirt from it is used to build the pond dikes, so, except for the internal ditch, the pond bottom is pretty close to the original land elevation. The Ewing Farm takes a low cost, extensive approach, stocking only 6–8 PLs per square meter. Arizona Shrimp Company has been stocking at about 33 PLs per square meter, but this year, for a number of reasons, it will probably drop back to about 6–10 per square meter. Both of these farms operate without aeration.
Until the beginning of 2002, the Ewing Shrimp Farm was operated by the Super Shrimp Group. Before its demise, Super Shrimp began an enormous project to expand the farm using earthen raceways and a large-scale, homemade biofiltration system that included rotating drums for particle removal, settling ponds, foam fractionators and ozone generators. Super Shrimp folded before it could get any of its systems completely operational.
Ewing Shrimp Farm will be working with Penaeus vannamei this year instead of P. stylirostris, and it is going to keep things very simple, so I would expect to see its production jump to about 650–700 kilograms per hectare this year.
In 2002, Desert Sweet held back on stocking some of its ponds, but Arizona Shrimp Company, with 80 hectares of ponds, more than took up the slack. In five years, the production of shrimp in Arizona increased from about 47 to about 243 metric tons per year. There won’t be any expansion in production area in 2003; it will stay around 136 hectares. Although three of the arms many not stock all of their ponds this year and one will drop back significantly in its stocking density, I think there will be an overall improvement in productivity, so I look for about 350–400 metric tons of farm-raised shrimp from Arizona in 2003.
Arizona Mariculture Associates: Like all shrimp farms, we’ve had good and bad harvests. In 2002, we averaged 33% survival in the lined ponds and about 46% survival in the dirt ponds. These are not numbers worth bragging about, but we are learning. Though survival wasn’t great, we did manage to keep our feed conversion ratios within reason (1.9:1 and 1.5:1 in the lined and dirt ponds, respectively).
The lined ponds produced 16–17 gram animals, and that’s about the best we can expect from them. In the dirt ponds, we averaged almost 24 grams.
We stocked some ponds as early as late April last year, and our last dirt pond was harvested at the beginning of December. The last lined pond was harvested on January 30, 2003. The farm is located in an area called "Agua Caliente" (hot water). Our main well comes in at 33° degrees C. This gives us a distinct advantage in the live shrimp market, which peaks in the winter months. We have carried a number of dirt and lined ponds over the winter, though the growth rate does not really justify the effort.
I hope to get productivity in the lined ponds up to about 12,000–14,000 kilograms per hectare in 2003, and the dirt ponds should produce around 2,200 kilograms per hectare.
We have successfully cultured broodstock-size shrimp for two years, but have not yet gotten a hatchery into operation. We maintain four families of broodstock and currently have shrimp from one of these families in an indoor recirculating maturation system. Within the next two weeks, we will finish assembling a prototype recirculating system for larval rearing and algae culture. We would like to work in conjunction with one of the companies focusing on the genetic improvement of shrimp breeding stock, making our shrimp available to them, so that they could develop improved lines for Arizona.
Problems: All four farms have experienced slow persistent mortalities. After the shrimp reach about 3–4 grams, we’ll periodically spot one or two dead animals around the pond edges. It’s not a big deal when you have a few hundred thousand shrimp in a pond, but you do know that something is not exactly right. This contrasts to periodic mass mortalities in July and August, when water temperatures can get above 33°C. These mortalities are clearly associated with the lunar cycle, peaking at full moon followed by a weaker peak at new moon. Problems with osmoregulation during the molting cycle are thought to play a part, especially in the mass mortalities.
We have also experienced on and off problems with tail cramping, particularly when sampling or harvesting, and especially during the hotter months. At our farm, this problem is more common in the lined ponds than in the dirt ponds, but is has occurred at all the other farms as well.
We know our water is deficient in magnesium and potassium, which seems to be characteristic of well water. We know there are other chemical problems, such as high calcium levels, low alkalinity and mineral ratios that are much different from seawater.
The bottom line seems to be that shrimp in Arizona are living on the edge, and it doesn’t take much to stress them into a dangerous situation. A lot of water exchange stresses the shrimp. It’s better to have a slow continuous exchange than periodic batch exchanges.
We modified our Rangen diets to include increased amounts of magnesium and potassium. Preliminary studies show that there was a significant difference in osmoregulatory capacity of shrimp at our farm in comparison to shrimp at Desert Sweet Farm, which were on a standard Rangen diet.
We are adding dolomite to our ponds at a rate of about 100 pounds per hectare per week in an effort to increase alkalinity and to get some magnesium into the water. We are also adding potash on a daily basis trying to maintain an increase of about 12 ppm of potassium, taking into account our constant water exchange, especially during the winter.
We have found that our shrimp do better in aerated water than in water that comes directly from the well. Hence, you see towers throughout our complex that aerate and degas, as well as cool the water during the hot months.
One of our mortal enemies is benthic blue-green algae, primarily Oscillatoria. When it lyses in the digestive system of the shrimp, it turns red, making processing difficult and, on rare occasions, interfering with the scheduling of live shrimp sales. Low salinity, slow-moving water, high pH and low alkalinity favor blue-green algae. We try to fight them as best as we can by introducing diatoms and varying the fertilization regime, but about the best we can do is to try to make sure that we keep benthic mats from getting established.
One very unusual problem that Arizona Shrimp Company and we experienced in 2002 was runaway high oxygen levels, without accompanying algae die-offs. Oxygen levels at Arizona Shrimp Company went over 20 ppm and caused significant mortalities in several ponds. We had one pond that got up to about 17 ppm and had steady mortalities from then on. It’s not clear whether the problem is actually toxic oxygen levels, or if the high oxygen readings are just indicative of the high density of blue-green algae, which may be producing toxins that have passed a certain lethal threshold when combined with other stress factors.
Dragonfly nymphs are a big problem. You either have to jump-start the shrimp so they are too big for the nymphs, or you have to limit the pond prep time to no more than seven days, so the shrimp have a chance to outgrow the nymphs.
Arizona Shrimp Company has the best average salinity of all the farms, very high alkalinity, high magnesium, and fairly low potassium, but still it had the same mortality problem that we had. In 2002, Tark Rush, farm manager, added magnesium and potassium to the feed and potash to the ponds and had fewer molting problems.
Marketing: None of the Arizona farms produces enough shrimp to successfully compete in the wholesale frozen shrimp market. So each of the farms has taken a slightly different approach to get the most for its product. Desert Sweet has all of its shrimp processed at a plant in Phoenix and then keeps it in cold storage. They have opened two restaurants in Phoenix, as well as a deli counter, and they have tried selling their own packaged products at various retail outlets. They also have their own retail specialty store where they sell party packs of frozen shrimp with various combinations of sauces.
Roger Drudge, who runs Ewing Shrimp Farm, and his wife, Michelle, have opened a small retail store in Yuma from which they sell shrimp, as well as fresh fish that they fly in weekly.
Arizona Mariculture Associates and at least one other farm have tried selling at some of the recreational vehicle parks in the area, as well as at various craft fairs and swap meets.
Arizona Shrimp Company has constructed its own processing plant that has the capacity to handle about 30,000 pounds per day. German Dao of Venezuela is the primary investor in of ASC, and he and co-owner/farm manager, Tark Rush, prefer to process their own heads-on product to avoid shipping costs and fees at other plants. Eventually, this plant will probably handle a lot of product for the other Arizona shrimp farms.
Because of our relatively low tonnage, Arizona Mariculture Associates has had to look for the most profitable market for its product. This year, about 90% of our production was sold live to Asian markets and restaurants. The buyer’s truck arrives at the farm several hours before harvest. We fill his insulated tanks with aerated pond water and then mix in salt to raise the transport salinity to about 12–15 ppt. Temperature in the transport tanks is adjusted to about 18°C in the summer and about 16°C in the winter. One truck can carry up to nine of the standard insulated totes (675 liter capacity), and each tote can handle between 250–275 pounds of shrimp, so we can send out about 2,500 pounds per trip.
We’ve tried various methods of extracting the shrimp from the ponds for live haul, including pumping, which is very stressful to the shrimp and results in very low transport survival. We’ve also tried various forms of bag nets and beach seines, and the results have not been satisfactory. What has consistently worked the best for us thus far is cast netting. It’s a lot of work, but our small, lined ponds are particularly well suited for this. For the dirt ponds, which often require multiple harvests, we are trying to develop a harvest method in the shallow end of the pond that works like a fish trap to concentrate the shrimp. Then there would be no need to drastically reduce pond water levels for each harvest.
With a lot of manual labor, we can usually harvest 2,000 pounds in about 1.5–3 hours, depending on which type of pond we are harvesting. When the shrimp come out of the pond, we put them through two wash tanks that simultaneously increase the salinity and reduce the temperature.
The transport method is simple. Six standard 12-volt battery operated air pumps are connected to a short strip of Bioweave aeration tubing in each tote. No oxygen is used, just air. About 140 pounds of live shrimp are dumped loose into the tote, while the other 140 or so pounds are divided equally among three plastic slotted boxes which are covered with a styrofoam top that is held in place by a bungee cord. These boxes float, provide a second tier for the shrimp and help buffer the movement of water in the tanks during transport.
Credits: I’d like to mention that Samir Kuri, Mario Dominguez and Cam Shaar are people who worked with me at Arizona Mariculture Associates. Craig Collins, Roger Drudge and Tark Rush are the managers of the other three shrimp farms in Arizona. They are listed both in recognition of the assistance they gave in providing relevant data for this presentation, but also as a measure of the close cooperation that exists between the operators of the four farms. It’s all for one and one for all when it comes to helping each other out, unless we’re talking about investors, in which case the normal rules of knife fighting apply.
Sources: 1. Copy of Josh Wilkenfelds’s Power Point presentation at Aquaculture America 2003 (Louisville, KY, USA, February 19, 2003). 2. Recording of Josh Wilkenfelds’s presentation at Aquaculture America 2003. 3. The World Aquaculture Society Abstracts Booklet. Different approaches to inland shrimp farming and marketing of Penaeus vannamei in the Arizona desert, a continuing struggle for a place in the sun. Joshua Wilkenfeld, Samir Kuri, Mario Dominguez, Camille Shaar, Craig Collins, Roger Drudge and Tark Rush. February 2003. 4. Bob Rosenberry, Shrimp News International, Update March 13, 2017.
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