Feeding Freshwater Prawns through Mechanical Means to Increase Yields and Size

Final Report for FNC14-962

Project Type: Farmer/Rancher
Funds awarded in 2014: $7,477.00
Projected End Date: 12/31/2014
Region: North Central
State: Ohio
Project Coordinator:
Don Maloney
Don's Prawns & More
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Project Information

Summary:

This study was done to see if there would be any difference between the yield and size of fresh water prawns fed two different ways. One pond was hand-fed and the other pond was fed with a mechanical device (we have affectionately named the shrimp shooter) which evenly distributes the feed over the pond.

We evenly distributed the pawns into the two ponds by hand counting them before putting them in the ponds.

The West pond was fed by the mechanical device, ‘the shrimp shooter’ and the East pond was fed by hand, throwing the feed out into the water.

The ponds were harvested on September 12 and 13, 2014.

Introduction:

90% of all shrimp/prawns that are sold in the US are imported!  Most imported shrimp comes from Southeast Asia (Thailand, Vietnam, China and India).  These and other countries are not known for following best practices in production especially with the use of “not for human consumption antibiotic drugs”.  According to the Kentucky State University Prawn Production Manual, two of the issues facing producers of freshwater prawns are 1) producing consistently sized product and 2) decreased yields (as high as 50%).  If we could determine the cause for the widely varying size and yield, we could develop best practices that would benefit our farm and the US industry as a whole.  If successful, this project could result in a value-added revenue stream from a sustainable product with a small investment of time.

This would not only lessen the environmental impact of overfishing the oceans by producing an aquaculture product that is locally grown, but help eliminate any disruption in the food chain by creating food chain security and reduce the environmental impact on planet Earth. With my proposal, I believe the end result will increase yields and produce a more consistent-sized prawn.

A Freshwater Prawn is territorial and cannibalistic and because of these traits, some studies suggest as much as a fifty percent loss after the initial stocking quantity. We plan to compare two feeding protocols – the first to distribute the feed by hand and the second to distribute the feed mechanically in a more uniform fashion. The end result is to see which produces freshwater prawns of more consistent size, weight and higher yield.

Most feeding is done by hand which entails slinging feed from a scoop over as much area as possible of the pond. This has an inherent problem with large areas of the pond not being covered with any feed at all, making it an inconsistent way of feeding. We created a low cost device that evenly spreads feed over the pond. We started calling this device “The Shrimpshooter”. To view the “Shrimpshooter” in action go to www.donsprawns.com and under the photo and video section click on the video.

We will stock two ponds using the same water supply and feeds to test the theory; one prawn pond fed by hand and the other prawn pond fed using the mechanical device. When thinking about this logically, the prawn by nature is cannibalistic and territorial. If you could deliver the feed to individual living areas (a version of meals on wheels), you should be able to reduce the cannibalistic behaviors with the result being larger and more consistent sized prawns at harvest-time. Again, with evenly spread feed, the prawns do not have to go out and search for food because it is delivered to them, and they do not have to go into another prawn’s territory with a high probability (as much as 50%) of not returning to their own territory. Reducing food induced territorial fighting will likely result in increased overall yields.

Project Objectives:

Prawns (shrimp) are sold and categorized by size and weight. A 16 Count is an average of 16 prawns per pound. A 25 to 30 Count would be much smaller in size and 25 to 30 prawns per pound. One pond will be fed by hand, and the other pond fed by the mechanical device we invented that evenly distributes feed throughout the pond. We feel the evenly distributed pond will have more consistently sized prawns and a higher yield. A higher yield means we can sell to more customers. More uniform sized prawns could also make the prawns more marketable to commercial organizations such as restaurants, an avenue of sales we have not even touched because they typically want and need a consistent size. We will drain the first pond (hand fed) and as in previous years, keep a record of the number of pounds taken from the pond. Prior to selling, we will do a count of how many prawns per pound. We will also do a physical count (prawns per pound) four to five times during the harvest and sale. We will also use a size indicator to check consistency and uniformity of size. A simple ruler would work. As in the Average Count, size samples would be taken through out the harvest. The second pond would then be drained and the same records kept. This will determine if even distributed feed has an effect on the general size of prawns and a higher yield rate. Photos could also be taken.

Cooperators

Click linked name(s) to expand
  • Dillan Maloney
  • Don Maloney
  • Katie Maloney
  • 12 FFA Students TBA

Research

Materials and methods:

 Originally, we decided to measure the pawns by length using rulers. We quickly discovered that was not going to work because the prawns are not perfectly straight. We switched to a scale measuring in ounces. We used ounces instead of metric because shrimp are sold in the store by weight and by count. For instance, if you buy 16 count shrimp at the store it means there are 16 shrimp per pound, which are fairly large shrimp. After weighing them, we sorted them into the three sizes and then sold according to size and weight.

Large- (1 ounce and over)
Medium- (1/2 ounce to just under 1 ounce)
Small- (less than ½ ounce)

The initial sample from each pond was counted and sorted by weight.

We also did other random Count samples for each pond which gave us an average Count. (Count- prawns/lb)

Research results and discussion:

Total yield-

Hand-fed pond- 385.6 lbs

Mechanical-fed  pond - 464.9 lbs (17% higher yield)

Initial Count and Weight Sample
Hand-fed (East) Pond 
Sample-209 prawn/7.3 lbs

small

 

medium

 

large

 (33 prawns/lb)

(23 prawns/lb)

 

(16 prawns/lb)

150 prawns

 

43 prawns

 

16 prawns

4.5 lbs

 

1.8 lbs

 

1 lb

61% small

 

25% medium

14% large

 Initial Count and Weight Sample
 Mechanical-fed (West) Pond
 Sample-185 prawns/8.2 lbs

small

 

medium

 

large

(30 prawns/lb)

(20 prawns/lb)

 

(14 prawns/ lb)

88 prawns

 

74 prawns

 

23 prawns

2.9 lbs

 

3.7 lbs

 

1.6 lbs

35% small

 

45% medium

 

20% large

 
Hand-fed pond (East)

Smaller yield total pounds 385.6 lbs

It took more prawns to make a pound than other pond. (Count-prawns/lb)
(33 Count East pond vs 30 Count West pond-small) 
(23 Count East pond vs 20 Count  West pond-medium)
(16 Count East pond vs 14 Count West pond-large) 

The hand-fed pond had a higher percentage of smaller sized prawns (61%) than West pond (35%)

61% of this sample (4.5 lbs/7.3 lbs) were classified as small
25% of this sample (1.8 lbs/7.3 lbs) were classified as medium
14% of this sample (1 lb/7.3 lbs) were classified as large

Mechanical-fed pond (West)

Higher yield total pounds 464.9 lbs

Bigger and meatier prawns (Count-prawns/lb)

The mechanical-fed pond had a higher percentage of large prawns (20%) than hand-fed pond (14%)

35% of this sample (2.9 lbs/8.2 lbs ) were classified as small
45% of this sample (3.7 lbs/8.2 lbs) were classified as medium
20% of this sample (1.6 lbs/8.2 lbs) were classified as large

Later in harvest (internally for fun) we created new size Jumbo (12 Count). At least 5 lbs kept for personal consumption

 

Impact of Results/Outcomes

June 5, 2014- The prawn hatchlings were delivered. Before putting into the ponds, we did a physical count to make sure we were putting the same amount in each pond. This was a time-consuming task because the hatchlings are very small ranging from 1/16 to ½ inch. It requires patience and paying attention to detail pouring tiny sized prawns from small containers to buckets and then eventually placing them into the ponds.

July 8, 2014-The prawns have grown approximately one inch and can now be seen darting around at night with the aid of a flashlight.

September 12 and 13, 2014-Harvested both ponds. East Pond-385.6 lbs. West Pond-464.9 lbs

September, 2014-This was the first year we sold prawns commercially. Don’s Prawns had a contract with a local seafood distributor for the large prawns. An organization to provide some colleges and businesses with locally grown food bought 40 lbs, and a local pizza place bought 10 lbs of smaller size prawns and used them on their pizzas.

We had our public harvest selling locally-grown prawns. We had enough for all our customers who came out that day.

We went to the Urbana fish and shrimp festival and had a booth and basically sold out.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

In the summer, the Fairfield County Soil and Water Conservation asked us to host a tour of the prawn ponds. It involved several different county offices. Before the tour, Don gave an overview about raising freshwater prawns. There was a discussion about the SARE grant with a lot of interest in the results.

Don's Prawns attended 'Licking County 30 mile Meal' in August and attended the Fairfield County 'Taste of Fairfield' in September. People were able to sample some of the prawns presented as shrimp cocktail.

I did an interview with a local radio talk show. It helped people become more aware of being able to grow fresh water prawns in Ohio, and a locally grown, sustainable product. There were a couple of people who came to the harvest who were interested in starting to grow fresh water prawns themselves.

We used high school students from both Fairfield Union FFA and Lancaster FFA to help with the harvest. It exposed them to aquaculture and growing fresh water prawns. A couple of the students from the Lancaster FFA wanted to do their own scientific research on whether or not keeping the prawns in oxygen before dispatching them keeps the flesh from becoming mushy.

After the harvest, we had a booth at the Urbana Fish and Shrimp Festival. After buying some prawns, one customer called  the Festival and asked to speak to me and said "These are the best prawns I had since leaving the Phillipines. My family fought over them, and I am sorry I did not buy more."

After final approval from SARE, the results will be on our web site.

Don's Prawns will be speaking at the Ohio Aquaculture Association trade show and meeting in January, 2015.

Project Outcomes

Recommendations:

Potential Contributions

Using the shrimp shooter or mechanical-fed device increases the yield of fresh water prawns. Obviously an increase in yield means more revenue. 

We were able to sell to more people, commercial businesses, and sell at the Urbana Fish and Shrimp Festival.

Future Recommendations

Use mechanical-fed devices for feeding fresh water prawns. It produces a higher yield and it is much easier to feed the prawns. At one point we were were walking around the pond carrying 40 lbs of feed to throw into the pond.

For less than $300.00, this device increased yields by 17%, and based on this year stocking rates increased our gross dollars on one pond by $ 951.60.

Another way to present this information, based on our current stocking rates of a sustainable product and our current operation (2 ponds) with an expected life cycle of 7 years for the shrimpshooter, this $300.00 investment would increases gross dollars to a total of $13,022.40 over the 7 year life cycle, while taking some pressure off of overfishing the Oceans

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.