How we grow our shrimp

Installation of shrimp farm infrastructure was started in 1996 at the southern end of the Old Highway 80/Highway 85 Corridor. Since then shrimp has been produced at irregular intervals and the farm fell into disrepair.  Beginning this year the farm was taken over and reconstituted under the name “West Valley Farms”.  This year 25 ponds will be seeded with post-larvae (Pls) and harvests will start in August

As described above the water source for growing shrimp is obtained from the aquifer that is located beneath the farm. The water depth is variable but underlays the farm at a depth of ~400 feet.  The water has a salinity ranging from 1.6 to 2.1 PPT, i.e., it is brackish and at the low end for shrimp production.  However, research and experience has taught farm management how to promote the growth of  Litopenaeus vannamei that can be successfully farmed under conditions in the Gila river basin.

How shrimp are grown and processed on West Valley Farms

Step 1:

Post-larvae are purchased from a hatchery that certifies they are specific pathogen free (SPF). They are shipped to Arizona in oxygenated 30 PPT water.  If directly placed into low salinity water they will not survive due to osmotic shock, therefore they must undergo a process of acclimation.

Over a period of `30 days the 30 PPT water in which the PLs arrived is slowly diluted with aquifer water until the water in which the shrimp are thriving is isotonic with the aquifer water.  In addition, during this 30 day acclimation period the Pls are fed a series of diets that change rapidly over the acclimation period. Water quality, i.e., measurement of ammonia, nitrites and nitrates, are performed daily. And at the same time the salinity is slowly reduced to that of the aquifer water.

Step 2:

Ponds having been filled, the PLs that have transitioned to juvenile shrimp are now ready to be seeded into the 25 ponds available this year.  A sample of each juvenile population Is netted and an average weight is calculated for the shrimp population.  Based on pond area, shrimp are seeded at concentrations ranging from 20 to 80 shrimp per square meter.

Step 3:

Shrimp are fed twice a day with the diet listed to the right. Pond water measurements of ammonia, nitrites, nitrates, temperature and dissolved oxygen levels are performed daily.

Step 4:

Harvesting commences when shrimp reach desired size, generally not <2.5 months.  Larger sizes being more desirable, partial harvests can be carried out from 2.5 to as long as 5.5 months. Partial harvests mean the pond biomass is reduced and the remaining shrimp grow to a larger size.

All ponds are sloped to the center along the linear axis.  In addition, the ponds are sloped along the linear axis towards a screened off pit area.  The effect is when the water is lowred and the screen is removed the shrimp are concentrated.  A large diameter flexible hose connected to a fish pump is then lowered into the  water and the shrimp are pumped to a dewatering conveyor machine. The dewatered shrimp coming of the end of the conveyor belt are dropped into a perforated basket tub liner containing 4oC fresh water in which a polyphenol oxidase inhibitor is suspended and allowed to reside for ~10 minutes with agitation.

After treatment the basket containing the shrimp is removed from the tank and transferred to another tank containing of 4oC fresh water. The suspended shrimp are stirred to remove any detritus and water is allowed to drain from the tank and shaved ice is layered over the shrimp before being transferred to the processing center.

When the desired amount of shrimp has been removed from the pond, water from the aquifer is used to restore the desired pond depth and grow out of the remaining shrimp can continue.

Step 5:

Freshly harvested shrimp are transported to the processing center along with a log of the time of harvest, the pond number, etc.  On arrival tubs of shrimp are moved to a quarantine area in the processing center.  The manager of the processing center at this point makes a decision as to how the shrimp are to be processed.

West Valley Farms
Corporate Address: 12725 W. Indian School Road, Suite E101, Avondale, Arizona 85392
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