Aeration and Salinity and Shrimp Farming

A Discussion from the Shrimp List

This was a long discussion with a couple of side themes (temperature, wind and thermal transfer) that, in the name of brevity, I decided not to cover here.  You can check out the entire discussion at The Shrimp List, a mailing list for shrimp farmers (complete reference in the Source below).

Laurence Evans (ecotao@yahoo.com): What’s your opinion on the various aeration systems: AIRE-O2, Aqua&Co, Combo and Force 7?  In high salinity conditions such as the Red Sea, would paddlewheels increase evaporation and therefore salinity?

M.E. Esmaeili (meesmaeili@yahoo.com): According to Dr. Claude Boyd at Auburn University, paddlewheels have the highest efficiency and aspirators have the second highest efficiency.  Diffusers are at the bottom of the list.  Paddlewheels are best for shrimp ponds because they increase oxygen levels and circulate the water.

Haydar Alsahtout (alsahtout@yahoo.com): Hi Mr. Esmaeili, Would you please provide the reference on Dr. Boyd’s paper that said paddlewheels had a higher efficiency than aspirators.

M.E. Esmaeili (meesmaeili@yahoo.com): Dear Haydar, My laptop was infected by a virus, and I lost many files.  I think you can find the paper on the Internet.

Sahu BK (sahu_b_k@yahoo.com): Dear Mr. Esmaeili and Mr. Haydar.  You can find the comparison of different forms of aerators by Dr. Boyd at the following link: http://www.fish.wa.gov.au/docs/aq/aq020/index.php?0308.

Over the last decade, we have observed several types of aerators in high salinity and high temperature waters like the Persian Gulf.  Paddlewheels have produced better results than aspirator and diffusion aerators.  We have never seen any changes in salinity related to the different kinds of aerators.

Brian Cohen (brian.cohen@aireo2.com):: When discussing the aeration efficiencies of the various aerators, the salinity level of the water has to be factored in. I believe the tests referenced to earlier in this discussion were conducted in fresh water, not in salt water.

There was a very interesting aerator comparison study published in Aquacultural Engineering in 1991 by Dr. Boyd and others that studied the affects of salinity on the standard aeration efficiencies (SAEs) of Taiwanese paddlewheels, Taiwanese copycat aspirators and AIRE-O2 aspirating aerators. The study said that aspirating aerators “Transferred oxygen to water more efficiently at salinities of 10-30 ppt than at lower salinities.” It also said that “Oxygen transfer by Taiwan-style paddlewheel aerators was unaffected by salinity in the range of 10-30 ppt.”

So in a nutshell, the SAE of an aspirator aerator increases as the salinity increases, whereas paddlewheel aerators SAEs remain relatively constant as salinity increases. In the end, the aerator, which had the highest SAE, was the AIRE-O2 aspirator at the higher salinity levels (10 to 30 ppm). We have found similar results in our company test pool.

I could find only the abstract for this article online, but if you drop me an email at brian.cohen@aireo2.com, I will be more than happy to send the complete study to you.

With regards to paddlewheels increasing salinities and/or heat loss, I do not believe there are any published tests or data supporting this. However, I do know Auburn University conducted a small test once, and it showed that 1-Hp of paddlewheel aeration per acre increased evaporation by 10%. Aspirator/AIRE-O2 aerators might increase evaporation slightly, but not nearly as much as paddlewheels.

Dallas Weaver (deweaver@mac.com): A 10% increase in evaporation today would cool the water and decrease the evaporation tomorrow (lower temperature).  The net effect would be close to nothing.  For shrimp ponds, mixing is critical so just measuring the mass transfer using the SAE method only tells part of the story.  You need to know the DO at the bottom, not at mid-depth.

The AIRE-O2 type device and diffused aeration systems look good at high salinities because of the changes in surface tension that allow smaller bubbles to be formed.

M.E. Esmaeili (meesmaeili@yahoo.com): Dear Brian, Several aerators were tested in the paper you mentioned.  One should not conclude from these tests that all aspirating aerators are equal to or superior in oxygen transfer to paddlewheel aerators.  Other papers by Dr. Boyd have shown that paddlewheels are better than aspirators.

Brian Cohen (brian.cohen@aireo2.com): Dear Mr. Esmaeili: Thank you for your reply and additional comments.  First it is important to note that there are two distinct paddlewheel type aerators, and they have very different SAEs.  The one you are referring to as the most efficient is the “Auburn paddlewheel”, often referred to as a “rotor-type paddlewheel”.  These units originated in the southern USA as the aerator of choice for the catfish industry and are generally 5-Hp and up, made of stainless or galvanized steel and quite expensive.  These were the aerators that Dr. Boyd said were the most efficient—in FRESHWATER tests.  The reason that you don’t see them on shrimp farms is their high costs and large Hp sizes (always better to distribute oxygen via ten 2-Hp units than two 10-Hp units).  Unfortunately, the Auburn style paddlewheel was not included in the saltwater test I mentioned yesterday, so we are not sure how it would perform in salt water compared to aspirators (AIRE-O2).

The other type of paddlewheel that was tested in this paper was the Taiwanese-style, plastic paddlewheel, commonly seen at shrimp farms because of its low cost and availability.

Lastly, I definitely think paddlewheel-type aerators have much higher evaporating rates than aspirator types simply because they are throwing water into the air versus injecting air into the water.  A properly designed aspirator should produce small air bubbles in the neighborhood of 2 mm.  Throwing water into the air from paddles definitely would lead to more evaporation than a properly designed aspirator which has very little surface to air interaction.

Sources: 1. The Shrimp List (a mailing list for shrimp farmers).  Aerator Comparison.  January 4-6, 2010.  2. Bob Rosenberry, Shrimp News International, January 14, 2010.

Country Reports

Asia

Video—Recreational Freshwater Prawn Fishing with Music

For a four-and-a-half-minute video of a bunch of kids fishing for freshwater prawns at a recreational fish-out operation somewhere in Asia, click on the link in the Source below.

Source: YouTube.  Fishing Prawns.  December 21, 2009.

Belgium

Leaching Minerals from Feed Pellets

Eric De Muylder (eric.de.muylder@skynet.be) posted the following item to the Shrimp List, a mailing list for shrimp farmers:

I am doing a survey on the leaching of macro-minerals from shrimp feed pellets.  If you would like me to test your feed, mail me a 200-gram sample of your 2.0 or 2.2 mm diameter pellets.  I will analyze them and send you the results for free.  For each sample, I will need the name of the feed mill, the brand name, the feed type and the country of origin.  The results will be published, but brand names will not be mentioned.  Only the country of origin will be mentioned.  If you are interested, please contact me at the above email address.  I need to discuss some details with you about shipping the samples.  I’m looking for a broad geographical spread.

Source: The Shrimp List (a mailing list for shrimp farmers).  Leaching of Minerals.  December 23, 2009.

Brazil

What Do Shrimp Do After They Eat?

From abstract: In this study, researchers looked at shrimp (Penaeus vannamei) activity after feeding in relation to feeding frequency.  The shrimp were kept in aquariums on a 12-light/12-dark cycle and fed a commercial feed three, four or seven times a day.  Every 15 minutes, the researchers collected data on exploration, feeding, swimming and inactivity.  Feeding and exploration were the highest for shrimp fed three times a day, swimming was greatest when animals received four feedings, and inactivity was highest for shrimp fed seven times per day.  The results indicate higher forage-related activities (exploration/ingestion) when feed was offered three or four times a day.

Source: Aquaculture Research.  Activity Pattern of the Marine Shrimp Litopenaeus Vannamei (Boone 1931) in Laboratory as a Function of Different Feeding Frequencies.  Patrícia Pereira de Lima (pattlyma@yahoo.com.br, Departamento de Fisiologia, Universidade Federal do Rio Grande do Norte, Caixa Postal 1511, Campus Universitário, 59078-970 Natal, RN, Brazil), Cibele Soares Pontes and Maria de Fátima Arruda.  Volume 41, Issue 1, Pages 53-60.  Published online on June 11, 2009.

Ecuador

Pirates Adopt New Methods

[Computer translation]: In mid-December 2009, in El Oro Province, located on the southern edge of the Gulf of Guayaquil, four shrimp farms were robbed by pirates.  The pirates are no longer attacking the boats that carry the shrimp to the processing plants, they are now coming on to the farms with machine guns and harvesting crews.  They usually arrive in the late afternoon on an incoming tide and depart early in the morning, threatening to kill any of the guards or pond workers that don’t follow their orders.  They have automatic weapons, large and fast boats, radio equipment, everything needed for a rapid and effective assault.

Segundo Calderon, president of the El Oro’s Chamber of Shrimp Producers, said one farmer lost $40 thousand worth of shrimp and another lost $6 thousand.

Source: Boletin Informativo (Ecuador’s Cámara Nacional de Acuacultura).  Editor, Jorge Tejada (jtejada@cna-ecuador.com).  Asaltos Constantes a Camaroneras Orenses.  December 18, 2009.

Indonesia

Government Should Build Feed Mills

Suhana, a marine biologist at the Bogor Institute of Agriculture, said shrimp farmers were complaining because feed prices at $1.08 a kilogram were about 15 percent higher than those elsewhere in the world.  He said the government should build local feed mills to bring feed prices down.  “Growers in Riau built their own mills and produce the feed, which sells for $10.78 per 50 kilogram sack [about $0.22 a kilogram],” Suhana said.  “It’s certainly more affordable.”

On December 29, 2009, the Ministry of Maritime Affairs and Fisheries proposed cutting the import duty on feed ingredients.  Syamsul Maarif, the ministry’s secretary general, said the tariff was burdening domestic fish and shrimp farmers by making feed more expensive.  But Suhana said cutting the five percent import duty was not a solution because it would not lower shrimp feed prices very much.

Source: Jakarta Globe.  Government Urged to Build Local Feed Mill to Spare Fish Farmers High Costs.  Arti Ekawati.  January 1, 2010.

Indonesia

IMNV

Infectious myonecrosis virus (IMNV) was first reported in Brazil in Penaeus vannamei in 2004.  In 2006, it was discovered in Indonesia and has since been reported in Thailand and southern China.  It appears to be vertically transmitted, making the movement of broodstock and infected postlarvae a likely source of disease.  There are no reported observations regarding its spread by vectors, although it is probably spread by birds and certainly transmissible horizontally.

Quite possibly broodstock imported from Brazil without adequate screening and quarantine led to the introduction of IMN in Indonesia and elsewhere.

The current spread of the virus suggests that ineffective control of animal movement and inadequate biosecurity measures could lead to widespread outbreaks.  Tools that could limit its spread include:

• Polymerase chain reaction screening of broodstock

• Screening postlarval shrimp before they are moved

• Treatment of effluents from processing plants to ensure that viruses are not dumped
into areas where they could impact shrimp farms

IMN can cause 40 to 70 percent mortality in ponds.  Given that 70% or more of the world’s farmed shrimp comes from China, Indonesia and Thailand, the risk is significant.  While no one can say for certain that proactive management will prevent this disease from spreading, it is sure that failing to take action will make the problem worse.

All aquaculture operations should audit their operations from a risk management standpoint and ensure that mechanisms are in place to prevent the avoidable.  With IMNV, following common-sense guidelines and restricting the movement of affected animals and broodstock can go a long way toward preventing the spread of this virus.

Information: Stephen G. Newman, Ph.D., AquaInTech, Inc., 6722 162nd Place SW, Lynnwood, WA 98037 USA (phone 1-425-787-5218, mobile 1-425-239-7682, fax 1-425-741-0857, email sgnewm@hotmail.com, webpage http://www.shrimpaquaculture.com).

Source: The Global Aquaculture Advocate.  Editor, Darryl Jory (dejry2525@aol.com).  Proactive Disease Management Counters ISA, IMN.  Stephen G. Newman.  Volume 12, Issue 6, Page 70, November/December 2009.

Madagascar

Chinese Fishing Company Takes Over Japanese-Owned Shrimp Farm

China National Fisheries Corp has officially taken over and started operating a company formerly run by Japan-based Maruha Group.  The new Chinese company is made up of the former companies—Somapeche, Somaqua and Sopeto—which were involved in shrimp fishing, farming and processing.  The new company has about 20 Chinese and nearly 500 local employees.

CNFC and Maruha signed the deal in July 2009, and the relevant legal formalities were completed in the latter part of November 2009.

Source: ChinaKnowledge.com.  CNFC Takes Over Fishing Project in Madagascar.  December 29, 2009.

Mexico

Wants Shrimp from Ecuador

My name is Guillermo Hernandez, from Guadalajara, Mexico.  I am interested in buying Penaeus vannamei from Ecuador.  It is very difficult to find Ecuadorian suppliers on the Internet.  I’m interested in approximately four containers per month.

Information: Guillermo Hernandez Kauffman, Halpoint Comercializadora, Guadalajara, Jalisco, México (phone 30-70-04-79, cell 331-273-0363, email ghernandez@halpoint.com, webpage http://www.halpoint.com).

Source: Boletin Informativo (Ecuador’s Cámara Nacional de Acuacultura).  Editor, Jorge Tejada (jtejada@cna-ecuador.com).  Interest in Purchasing Vannamei Shrimp (computer translation).  January 5, 2010.

Mexico

Sonora—Update

In the early 1980s, shrimp farming was initiated in the state of Sonora through government-sponsored cooperatives.  By the end of the decade, however, the private sector began investing in shrimp farming, and today private farms represent the majority of the 23,523 hectares of shrimp farms in the state, making Sonora the leading aquaculture state in the country.  Some harvests have reached records of six metric tons per hectare, while the state average is 3.8 tons.  Since 2000, shrimp farms in Mexico have produced more shrimp than the fishing fleet.

The Sonora Zoosanitary Comittee (COSAES) has made a major contribution to the development and success of shrimp farming in Sonora.  COSAES was founded in 2002 and is a joint organization between farmers and state and federal government agencies with the purpose of monitoring and maintaining the high sanitary status of aquaculture products in Sonora.

Information: John Cooksey, World Aquaculture Conference Management, P.O. Box 2302, Valley Center, California 92082, USA (phone 1-760-751-5005, fax 1-760-751-5003, email worldaqua@aol.com, webpage https://www.was.org/Main/Default.asp).

Source: The Abstracts of World Aquaculture 2009 (on CD).  Role of the Zoosanitary Comittee: COSAES (Comite de Sanidad Acuicola del Estado de Sonora) and Its Impact on Sonora State Shrimp Farm Productivity.  Miguel Olea (molea@soles.com.mx).  Veracruz, Mexico, September 2009.

Philippines

New CPF Feed Mill

Thailand’s largest agribusiness company Charoen Pokphand Foods Public Co., Ltd., is building a $51 million aquafeed mill 80 kilometers north of Manila.  The mill will produce pelleted, crumbled and extruded fish and shrimp feeds using the latest technology and equipment acquired from China and Europe.  The plant has a capacity of 114,000 metric tons a year.  The project will employ 209 people and will start commercial operations in January 2011.

CPF also plans to build a shrimp feed mill on the island of Cebu (550 kilometers south of Manila in the Visayan Islands) with a production capacity of 30,000 tons a year.

As one of Asia’s biggest food conglomerates, Charoen Pokphand Foods is primarily engaged in animal feed production, animal farming (especially poultry and shrimp), meat processing and the manufacturing of food products.  Its headquarters are located in Bangkok, Thailand.  It employs over 23,000 people and had record sales of $4.8 billion and a net profit of $180 million in 2008.

Source: Business Insight.  Thai Firm to Invest P2.3B in Aquafeed Production.  Irma Isip.  December 28, 2009.

South Africa

Wanted—Investors/Partners, Two Opportunities

1. A sustainable, patentable, revolutionary shrimp production system that shows

tremendous profit potential (based on eight years of international research

and development).

2. A tropical aquaponics system with low energy input and high productivity.

Information: prawnaquacultureinrsa@hotmail.com.

Source: AquaNic (The Aquaculture Network Information Center, a gateway to the world’s electronic aquaculture resources).  Jobs Directory in cooperation with the WAS Employment Service.  Search jobs.  Investor/Partner (http://aquanic.org/jobs/jobinfo.asp?jobid=3308).  Posted January 10, 2010.

Thailand

CPF Expects Growth of 10% in 2010

On December 25, 2009, Adirek Sriprathak, Managing Director of Charoen Pokphand Foods, said 2009 was a good year for the company.  “For next year, we are not expecting a big jump in sales.  We see growth of about 10 percent.”  CPF will spend about $150 million in 2010 on the expansion of its overseas plants and on investments in its aquaculture business in Thailand, he added.

Source: Reuters/India.  Thai CP Foods Raises 2010 Revenue Growth to 10 Pct.  Reported by Satawasin Staporncharnchai, written by Viparat Jantraprap and edited by Martin Petty.  December 25, 2009.

United States

California—Forrest Gump and the Bubba Gump Seafood Company

Point Loma native Anthony Zolezzi comes from a long line of San Diego tuna fisherman dating back to the late 1800s.  As a kid, he went out on the boats and caught fish with his family.  That experience shaped his future.

Decades later, while trying to engineer a turnaround for a financially troubled seafood company in Los Angeles that sold shrimp, lobster and crab, Zolezzi bought the rights to the “Bubba Gump Seafood Company”.  He said, “I was six months into it and failing.  One Sunday, I went to the movies and saw Forrest Gump.  The next day, I was at Paramount Studios and became the owner of the name Bubba Gump Shrimp Company—which then became the new restaurant venture that turned the seafood company around.  Who knew that going to see a movie would help me figure out how to bail out a $400 million company?”

Source: San Diego.com.  San Diego Business/Penguins, Forrest Gump and Unlikely Business Solutions.  Ellene Zimmerman.  December 27, 2009.

United States

Washington DC—Gary Jensen, USDA Coordinator of Aquaculture Research

Gary Jensen is National Program Leader for Aquaculture with the US Department of Agriculture’s National Institute of Food and Agriculture where he administers, evaluates and coordinates aquaculture research and extension programs in partnership with land grant institutions, client organizations and government agencies.  He is also Executive Secretary for the federal coordinating Joint Subcommittee on Aquaculture under the National Science and Technology Council.

Source: Program for the 22 Annual North Carolina Aquaculture Development Conference (January 21-23, 2010, Atlantic Beach, North Carolina).  No Date.  Received January 12, 2010.

Venezuela

China to Invest in Shrimp Farming

During the week of December 21-25, 2009, Venezuelan and Chinese government officials and business leaders met in Caracas to discuss bilateral relations.  As a result of the accords signed at the meeting, Venezuela will increase its supply of oil to China to more than 600,000 barrels per day in 2010, and China will increase its investments in Venezuelan agriculture, infrastructure, mining and energy production.  Chinese state-owned and private companies also agreed to invest in Venezuelan railways, fish and shrimp production.

Source: VenezuelAnalysis.com.  Venezuela and China Consolidate Strategic Alliance, Expand Bilateral Trade.  James Suggett.  December 25, 2009.

Vietnam

Breeding Centers for Shrimp

Prime Minister Nguyen Tan Dung has approved a project worth $3.8 billion over ten years to develop new varieties of plants, livestock and aquatic animals.  A large part of the sum will be used to develop high-yielding varieties of rice, fruit trees, vegetables, coffee trees, basa fish and tiger shrimp.

Source: VovNews.  Around US$3.8 Billion for Agricultural Development.  December 29, 2009.

Vietnam

Crocodiles Invade Shrimp Ponds in the Mekong Delta

From December 14 to 24, 2009, crocodiles that escaped from a reptile farm invaded shrimp ponds in Tan Phu District in southern Ca Mau Province.

Source: Vietnam News.  Crocodiles Escape from Farms.  December 26, 2009.

Vietnam

Expects to Export 150,000 Metric Tons of Penaeus vannamei in 2010

Vietnam exported over $1.5 billion worth of frozen shrimp products in 2009, the only seafood export that managed to grow amid the global economic crisis.  According to the Vietnam Association of Seafood Exporters and Producers (VASEP), the quantity of shrimp exported in 2009 will be close to 190,000 metric tons, up 7 percent in volume and 1 percent in value from 2008.

Penaeus vannamei has gradually become an important export staple.  In 2009, Vietnam exported around 50,000 tons of P. vannamei, earning $300 million.  Export volume of vannamei is expected to triple to 150,000 tons in 2010, earning around $500 million.

Source: BERNAMA.com.  Vietnam’s Frozen Shrimp Exports Strive Amid Crisis.  January 2, 2010.