Tilapia and aquaculture news

Fishermen in Queensland, Australia suspect a human hand is helping invasive fish to spread throughout the state’s rivers and dams. African tilapia fish have spread considerably further than predicted by biologists and fishery authorities and local fishermen now worry that the approaching wet season will end efforts to control the tilapia invasion in already infected waters.

According to Peter Jackson, a freshwater fisheries scientist with the Queensland Government, the findings of tilapia populations at the top of river systems suggest that someone is deliberately introducing this fish to Queensland’s waterways.

“Our pest fish strategy has always been one of trying to contain fish to where they are and not let them spread, Jackson says. Unfortunately recently it’s obvious that someone’s been spreading them around.”

There exists many different species of tilapia but now of them are native to Australia. Tilapias are popular farm fishes and have been kept in ponds for thousands of years; the Ancient Egyptians did for instance raise tilapia in ponds along the River Nile. Tilapia is also an appreciated aquarium fish among aquarists with large enough tanks.

Tilapias are adaptable fish and the fact that they thrive in tropical Queensland comes as no surprise. Once tilapia has established a breeding population in a lake or waterway, it is almost impossible to eradicate them – at least if you aren’t willing to sacrifice a lot of native species in the process. In the warm waters of Queensland, tilapia can breed several times per year and since they are a mouth-brooding species each batch have a high survival rate.

Tilapia is now found in one of Queensland’s biggest river systems, the Burdekin, where they compete with native species for food and space. According to David Bateman, executive officer of the amateur fishing lobby group Sunfish, tilapias also cause trouble for native species by disturbing the water when they build their circular nests to breed.

Jackson now calls for more research to determine the risks of having tilapia in Queensland waters. “Research needs to be done to really determine exactly what their impact is, but we’re taking the precautionary approach and saying well, let’s not find out, let’s keep them out of as many river systems as we can – because once they do get into a river system, unless we find out really quickly, and they’re in an isolated area, our chances of getting them out are almost zero”, Jackson explains.

Jackson fears it might already be too late to save the Burdekin from the tilapia invasion, since the wet season is rapidly approaching. Resources will instead have to be focused on protecting remaining river systems.

Research published in the online open access journal BMC Public Health show that Nile tilapia (Oreochromis niloticus) can be a valuable aid in the fight against mosquitoes; the animal responsible for transmitting malaria to humans. Today, malaria can be fairly easily treated and even cured, but a millions of people living in developing countries do not have access to malaria medication.

The emerging threat of pesticide resistance, and the fear of how poisons affect the rest of the ecosystem, has caused a comeback for the interest in biological mosquito control methods. The Nile tilapia’s fondness of mosquitoes has been known since the early 1900s, but the advent of powerful insect poisons during the 20^th century steered research away from biological control and into chemical solutions.

After receiving funding from the Government of Finland, the BioVision Foundation in Switzerland and the Toyota Environment Foundation, researchers Annabel Howard and Francois Omlin from the International Centre of Insect Physiology and Ecology in Nairobi, Kenya, introduced Nile tilapia (Oreochromis niloticus L.) to abandoned fishponds in the Kisii Central District. Located in western Kenya, the Kisii Central District has over 2000 pediatric malaria cases per annum.

After 15 weeks of monitoring pond life and comparing the restocked ponds with a control pond nearby, Howard and Omlin could show that the tilapias had reduced the region’s primary malaria vectors, the mosquitoes Anopheles gambiae s.l. and Anopheles funestus, by over 94 percent. Mosquitoes from the genus Culex were simultaneously reduced by 75 percent.

“O. niloticus fish were so effective in reducing immature mosquito populations that there is likely to be a noticeable effect on the adult mosquito population in the area,” Howard says.

Nile tilapia thrives in the Kenyan climate and fish once added to a pond will find its own food and readily reproduce; thus providing a sustainable solution to the problem with mosquito. Nile tilapia is also a popular food fish in Kenya so a pond risking becoming over-populated with tilapia just needs a visit from some hungry anglers to be back on the right track again.

Two students at New York’s Trinity school made a surprising discovery when they used a new genetic barcoding method to test fish sold in fish stores and served in restaurants on Upper Manhattan. Out of 60 different samples, 14 turned out to be mislabelled.

The study was made as a part of a school project by high-school students Kate Stoeckle, 18, and Louisa Strauss, 17 who sent their collected specimens to the University of Guelph in Canada for analysis. Four samples could not be identified by the genetic barcoding identification technique, but out of the remaining 56 samples no less than 25 percent turned out to be sold under false label.

All 14 cases of erroneously labelled fish were comparatively cheap fish being sold as a more expensive and sought after species, which pretty much rules out innocent human error. Sly New York fish shops and restaurants are clearly profiting from purchasing cheap fish and knowingly renaming it.

One Upper Manhattan sushi restaurant did for instance serve their guests Mozambique tilapia when they ordered White tuna, while another restaurant in the same area had Mediterranean Red mullet on the menu but Spotted goatfish from the Caribbean Sea on the plates.

Not getting what you pay for or living under the false impression that White tuna tastes like Mozambique tilapia is naturally problematic, but this type of mislabelling is not only a problem for fish loving Manhattanites - it poses a risk for endangered fish species as well. As more and more consumers actively chose not to order endangered species, this type of fraudulent labelling makes it possible for restaurants and fish shops to keep purchasing endangered fish from fishing fleets and selling it off as non-endangered species to unsuspecting customers.

Stoeckle and Strauss did for instance find two specimens of the endangered Acadian redfish (Sebastes fasciatus) sold as Red snapper. While the Red snapper may also be getting increasingly rare along the North American coast, the Acadian redfish has been listed as Endangered (EN) on the IUCN Red List of Threatened Species since 1996.

In response to a recent report from Wake Forest University about high levels of Omega-6 in tilapia, an international coalition of 16 doctors* spoke out today, lead by Dr. William Harris of the Sanford School of Medicine. According to the coalition, tilapia is a part of a healthy diet since it is low in total and saturated fat and high in protein and “replacing tilapia or catfish with ‘bacon, hamburgers or doughnuts’ is absolutely not recommended”.

The coalition, including one expert from Wake Forest University, says that even though fish like catfish and tilapia aren’t rich in omega-3 fatty acids, they are still better choices than most other meat alternatives. The doctors also explained that omega-6s are found not only in fish like tilapia, but in many other types of food as well, such as chicken, nuts, vegetable oils, and whole-wheat bread.

According to both the American Heart Association and the American Dietetic Association, omega-6 fatty acids are, like omega-3s, heart-healthy nutrients which should be part of everyone’s diet.

*
United States
William S. Harris, PhD, FAHA Sr. Scientist and Director Metabolism and Nutrition Research Center Sanford Research/USD Sioux Falls, SD (605) 328-1304

Co-signers: Thomas Barringer, MD, FAHA Medical Director, Center for Cardiovascular Health Carolinas Medical Center Charlotte, NC (704) 446-1823

Marguerite M. Engler, RN, PhD, FAHA Professor Dept. of Physiological Nursing UC San Francisco, CA

Mary B. Engler, PhD, RN, MS, FAHA Professor and Director Cardiovascular and Genomics Graduate Program Dept. of Physiological Nursing UC San Francisco, CA

Penny Kris-Etherton, PhD, RD, FAHA Distinguished Professor of Nutrition Penn State University University Park, PA (814) 863-2923

Dariush Mozaffarian, MD, DrPH, DSc Assistant Professor Harvard School of Public Health Boston MA 617-432-2887

Joyce A. Nettleton, DSc Editor, PUFA and Fats of Life Newsletters Denver, CO 303-296-9595

Eric Rimm ScD, FAHA Associate Professor Harvard Schools of Medicine and of Public Health Boston MA 617-432-1843

Larry Rudel, PhD, FAHA Professor of Biochemistry Wake Forest University Winston-Salem, NC (336) 716-2821

Frank Sacks, MD, FAHA Professor of Cardiovascular Disease Prevention Harvard School of Public Health Boston, MA (617) 432-1420

Australia
Peter Howe, PhD Professor and Director Nutritional Physiology Research Centre University of South Australia, Adelaide

Andy Sinclair, PhD Chair in Human Nutrition School of Exercise and Nutrition Sciences Deakin University Burwood, Australia

Canada
Bruce Holub, PhD Professor Emeritus Dept of Human Biology and Nutritional Sciences University of Guelph, Ontario, Canada

Germany
Clemens von Schacky, MD Cardiology Ludwig Maximilians-Universität München Munich, Germany

Korea
Yongsoon Park, PhD Chair and Assistant professor Department of Food and Nutrition Hanyang University Seoul, Korea

United Kingdom
Philip Calder, PhD Professor of Nutritional Immunology University of Southampton, UK

According to researchers from Wake Forest University School of Medicine*, farm-raised tilapia contains very low levels of beneficial omega-3 fatty acids and very high levels of omega-6 fatty acids.

In an article published in the July edition of Journal of the American Dietetic Association**, the Wake Forest researchers say that combination of low amounts of omega-3 and high amounts of omega-6 could make the fish a potentially dangerous food source for some patients with heart disease, arthritis, asthma and other allergic and auto-immune diseases that are particularly vulnerable to an “exaggerated inflammatory response.”

“For individuals who are eating fish as a method to control inflammatory diseases such as heart disease, it is clear from these numbers that tilapia is not a good choice,” the article says.

Scientists say their research revealed that farm-raised tilapia and catfish “have several fatty acid characteristics that would generally be considered by the scientific community as detrimental”. According to the article, the levels of long-chain omega-6 fatty acids are higher in farm raised tilapia than in 80-percent-lean hamburger, doughnuts and even pork bacon.

“All other nutritional content aside, the inflammatory potential of hamburger and pork bacon is lower than the average serving of farmed tilapia,” Wake Forest researchers explain.

The researchers used gas chromatography to analyse the contents of the fish and tested variety of fish from several different sources, including supermarkets in four U.S. states, seafood distributors that supply restaurants and supermarkets, two South American companies, and fish farms in several countries. Pending analysis, all samples were snap-frozen to preserve nutrients.

The gas chromatography analysis showed that farmed tilapia contained less than 0.5 grams of omega-3 fatty acids per 100 grams of fish. Farmed salmon and trout did however contain considerably higher amounts; almost 3 grams and 4 grams, respectively.

The analysis also showed that farmed tilapia contained higher amounts of omega-6 acids than both salmon and trout. In farmed tilapia the ratio between long-chain omega-6 to long-chain omega-3 average about 11:1, which can be compared to the average ratio of less than 1:1 found in salmon and trout.

The importance of the omega-6 / omega-3 ratios vs. the concentration of long-chain omega-3 alone is currently being heavily debated by scientists.

Dr Floyd H. “Ski” Chilton***, the senior author of the Journal article, said tilapia is easily farmed using inexpensive corn-based feeds, which contain short chain omega-6s that the fish very efficiently convert to AA [omega-6] and place in their tissues.

“We are all familiar with the classical Hippocratic admonition, Primum no nocere, ‘First, do no harm.’ I think it behooves us to consider this critical directive when making dietary prescriptions for the sake of health,” Chilton said. “Cardiologists are telling their patients to go home and eat fish, and if the patients are poor, they’re eating tilapia. And that could translate into a dangerous situation.”

* Wake Forest University School of Medicine, along with North Carolina Baptist Hospital and Wake Forest University Physicians, is part of the Wake Forest University Baptist Medical Center system. It is located in Winston-Salem, North Carolina in the United States.

** http://www.adajournal.org/

***Floyd H. “Ski” Chilton, Ph.D., professor of physiology and pharmacology and director of the Wake Forest Center for Botanical Lipids

Tilapia has been farmed in ponds for thousands of years, and the Ancient Egyptians are for instance known to have raised Nile tilapia in ponds along the river Nile. During the 1950s an important step in the history of farmed tilapia was taken when Tel Aviv University zoologist Prof. Lev Fishelson developed a hybrid of tilapia that could withstand both high salinity levels and high temperature – a fish ideal for growing in desert ponds near the ocean. Israel comprises vast areas of land where the conditions are too arid for traditional crop growth and the available underground water is too salty for many animals and plants. Fishelson’s hybrid tilapia was therefore welcomed with open arms by Prof. Fishelson’s fellow countrymen.

When fish is farmed in countries where water is a scarcity, the water is usually meticulously managed. Instead of releasing the water at each harvest, a practise common among fish farmers living in more humid parts of the world and one which can easily lead to overt-fertilization of nearby water ways, the water is saved and used to grow algae. They algae will grow quickly by feeding off the organic waste products left by the fish and can soon be harvested as food for cattle and poultry or be sold for use in industrial products like dye and medicine. But this is not enough; once the algae are gone the water can be used to irrigate salt-tolerant crops like tomatoes to yield a third harvest.

In addition to being remarkably tolerant to salt and heat, Fishelson’s hybrid tilapia exhibits a strangely skewed sex-ratio. When certain species of tilapia are crossed, the resulting offspring will be virtually all male and Fishelson’s hybrid tilapia. Any females in the batch are normally the result of foreign genetic material in the parent fish, caused by earlier hybridization. Tilapia readily hybridizes with closely related species even in the wild.

In Fishelson’s hybrid tilapia, roughly 95% of the offspring is male which has made it an appreciated choice for fish farmers since fish that do not spend any energy on reproducing reaches a marketable size faster. Male tilapias are also known to grow faster and bigger than females.

From July to September 2008, 52 restaurants in Florida, United States where cited for allegedly misrepresenting what they serve to the public.

Embarrassingly enough, one of them was the Miami Police Cafeteria who was fined $750 when an inspector from the Florida Department of Business and Professional Regulation noticed that the cafeteria was serving the cops Basa fish claiming it was Grouper.

Another example of a cited restaurant was Thai Sushi Express, where the operator claimed they used Tilapia instead of Red Snapper because “they are the same kind of fish“.

In the Coconut Creek Grille and Tap House, the Pangasius purchased form Sysco is magically transformed into Grouper, and something similar must be going on at Wreck in Marathon where Grouper is advertised on the menu three times but no Grouper can be found on hand, in storage or on any invoice. In the Siam Lotus Room, the operator didn’t even know that Swai and Grouper are not the same fish.

The price difference between low-price fish like Basa and Tilapia and high-price fish like Grouper and Red Snapper is staggering, so there is quite a lot of money to be made for the wily restaurant owner who manages to convince its customers that the cheap, and often farmed, fish they have on their plates are expensive wild caught ocean dwellers.

According to fish connoisseur Mike Montella of Mr. Fish gourmet seafood in Pompano Beach, the difference in taste between Tilapia and Red Snapper is staggering. “It doesn’t taste nearly as good as snapper, and I’m surprised any restaurant would do that knowingly,” says Montella.

Getting a less tasty fish than you pay for is not the only problem here; popular replacement fishes like Basa and Tilapia is sometimes raised in polluted waters. When consumers don’t get a chance to know what they’re actually eating, it becomes impossible for them to make an informed decision. A lot of Basa fish are for instance raised in the heavily the polluted Mekong River in Southeast Asia.

If you wish to see a list of Florida restaurants that have been recently cited for allegedly mislabelling ingredients, Justnews.com is offering one here: http://www.justnews.com/news/17907148/detail.html